pituitrin and Acidosis

For optimal performance of exercising muscle, the charge state of proteins must be maintained; the pH environment of protein histidine imidazole groups must be coordinated with their pK. During exercise, increasing temperature and osmolality as well as changes in strong ions affect the pK of imidazole groups. Production of strong organic anions also decreases the concentration difference between strong cations and anions (strong ion difference, or [SID]), causing a metabolic acidosis in peripheral tissues. Central chemoreceptors regulate PCO2 in relation to the [SID] of brain fluids to maintain a "constant" brain [H+]. In addition, increased osmolality, angiotensin II, and vasopressin during exercise may stimulate circumventricular organs of the brain and interact with chemical control of ventilation. Changes in [SID] of brain fluids during exercise are negligible compared to systemic decreases in [SID]; thus, regulation of PCO2 to maintain brain [H+] homeostasis cannot simultaneously compensate for greater changes in [SID] in peripheral tissues.

Topics: Acid-Base Equilibrium; Acidosis; Animals; Exercise; Homeostasis; Humans; Hydrogen-Ion Concentration; Osmolar Concentration; Physical Conditioning, Animal; Respiration; Vasopressins

Nonsteroidal antiinflammatory drugs can adversely affect the kidney. They may induce sodium retention and antagonize the action of diuretics, impair free-water clearance and cause hyponatremia, and prevent aldosterone production and cause hyperkalemic hyperchloremic acidosis. If patients taking these drugs are exposed to a renal insult, acute renal failure becomes more likely. Similarly, patients with chronic renal disease who are taking them appear to be at greater risk of chronic renal failure. However, not all renal effects of nonsteroidal antiinflammatory drugs are adverse. Beneficial effects have been reported in patients with Bartter's syndrome and in those with severe orthostatic hypotension.

Topics: Acidosis; Acute Kidney Injury; Aged; Anti-Inflammatory Agents; Bartter Syndrome; Female; Humans; Hyponatremia; Hypotension, Orthostatic; Ibuprofen; Indomethacin; Kidney; Kidney Failure, Chronic; Lupus Erythematosus, Systemic; Nephrotic Syndrome; Prostaglandin Antagonists; Sodium; Vasopressins

The rate of acid excretion by the kidney appears to be determined by factors regulating the site and the rate of sodium reabsorption, rather than by a homeostatic mechanism that responds to systemic pH. This hypothesis, although unconventional, is supported by much experimental evidence, and it accounts for a wide variety of clinical and physiologic findings that heretofore have been difficult or impossible to explain.

Topics: Absorption; Acid-Base Imbalance; Acidosis; Alkalosis; Ammonia; Animals; Bicarbonates; Carbon Dioxide; Cations; Chronic Disease; Dogs; Homeostasis; Humans; Hydrogen-Ion Concentration; Hypercapnia; Kidney; Kidney Tubules; Minerals; Nephrons; Sodium; Vasopressins

Topics: Acidosis; Acute Kidney Injury; Alkalosis; Amyloidosis; Hodgkin Disease; Humans; Hyperkalemia; Hypernatremia; Hypertension, Renal; Hypokalemia; Kidney; Kidney Concentrating Ability; Kidney Diseases; Multiple Myeloma; Neoplasms; Nephritis; Nephrotic Syndrome; Osmolar Concentration; Urine; Vasopressins; Water-Electrolyte Balance

Topics: Accidents, Traffic; Acidosis; Acute Kidney Injury; Adult; Aged; Alkalosis; Aortic Diseases; Aortic Rupture; Body Composition; Calorimetry; Cholecystectomy; Convalescence; Craniocerebral Trauma; Dehydration; Duodenal Ulcer; Endocrine Glands; Female; Homeostasis; Humans; Iliac Artery; Infusions, Parenteral; Kidney; Lung Neoplasms; Male; Metabolism; Middle Aged; Natriuresis; Pancreatitis; Peptic Ulcer Perforation; Postoperative Care; Postoperative Complications; Thoracic Injuries; Thrombosis; Vasopressins; Water-Electrolyte Balance

Topics: Acid-Base Equilibrium; Acidosis; Animals; Blood Pressure; Central Venous Pressure; Denervation; Dexamethasone; Humans; Infusions, Parenteral; Kanamycin; Oxygen Inhalation Therapy; Rabbits; Shock, Surgical; Spleen; Urine; Vasopressins

Vasopressin (arginine vasopressin, AVP) plays a crucial role in maintaining body fluid homeostasis. Excessive release of vasopressin can lead to hyponatremia. Changes in cerebral circulation during vasopressin-induced chronic hyponatremia are not elucidated. The present study has been designed to investigate the effect of chronic vasopressin-induced hyponatremia on the regulation of the tone of the middle cerebral artery (MCA) of the rat. Chronic hyponatremia was induced in vivo with the help of vasopressin, released continuously from subcutaneously implanted ALZET mini-osmotic pumps, and a liquid diet. After 3.5 days of chronic hyponatremia, the plasma Na

Topics: Acetylcholine; Acidosis; Animals; Cerebrovascular Circulation; Hyponatremia; Male; Middle Cerebral Artery; Nitric Oxide; Potassium Channels; Rats; Rats, Wistar; Sodium; Vasopressins

During the brain's innate immune response microglia, astroglia and ependymal cells resolve/repair damaged tissue and control infection. Released interleukin-1beta (IL-1beta) reaching cerebroventricles stimulates circumventricular organs (CVOs; subfornical organ, SFO; organum vasculosum lamina terminalis, OVLT), the median preoptic nucleus (MePO), and magnocellular and parvocellular neurons in the supraoptic (SON) and paraventricular (PVN) nuclei. Hypertonic saline (HS) also activates these osmosensory CVOs and neuroendocrine systems, but, in contrast to IL-1beta, inhibits the peripheral immune response. To examine whether the brain's innate immune response is attenuated by osmotic stimulation, sterile acidic perfusion fluid was microdialyzed (2 microl/min) in the SON area of conscious rats for 6 h with sterile HS (1.5 M NaCl) injected subcutaneously (15 ml/kg) at 5 h. Immunohistochemistry identified cytokine sources (IL-1beta(+); OX-42(+) microglia) and targets (IL-1R(+); inducible cyclooxygenase, COX-2(+); c-Fos(+)) near the probe, in CVOs, MePO, ependymal cells, periventricular hypothalamus, SON, and PVN. Inserting the probe stimulated magnocellular neurons (c-Fos(+); SON; PVN) via the MePO (c-Fos(+)), a response enhanced by HS. Microdialysis activated microglia (OX-42(+); amoeboid/hypertrophied; IL-1beta(+)) in the adjacent SON and bilaterally in perivascular areas of the PVN, periventricular hypothalamus and ependyma, coincident with c-Fos expression in ependymal cells and COX-2 in the vasculature. These microglial responses were attenuated by HS, coincident with activating parvocellular and magnocellular neuroendocrine systems and elevating circulating IL-1beta, oxytocin, and vasopressin. Acidosis-induced cellular injury from microdialysis activated the brain's innate immune response by a mechanism inhibited by peripheral osmotic stimulation.

Topics: Acidosis; Animals; Brain; Disease Models, Animal; Ependyma; Immunity, Innate; Interleukin-1beta; Male; Microdialysis; Microglia; Midline Thalamic Nuclei; Osmosis; Oxytocin; Rats; Rats, Sprague-Dawley; Saline Solution, Hypertonic; Supraoptic Nucleus; Vasopressins

Topics: Acidosis; Ammonium Chloride; Animals; Aquaporin 2; Aquaporins; Dehydration; Disease Models, Animal; Vasopressins

Although it is established that the fetus can successfully withstand a single, acute hypoxaemic challenge during gestation, little is known about what effects prevailing adverse intrauterine conditions might have on the fetal response to acute hypoxaemia. The aims of this study were therefore: (1) to characterise the effects of prevailing and sustained hypoxaemia, acidaemia or hypoglycaemia on the fetal cardiovascular responses to an episode of acute hypoxaemia; and (2) to determine the effects of these adverse intrauterine conditions on mechanisms mediating these cardiovascular responses. Thirty-three Welsh Mountain sheep fetuses were chronically instrumented (1-2 % halothane) between 117 and 125 days of gestation (term is ca 145 days) with amniotic and vascular catheters and with a transit-time flow probe around a femoral artery. The animals were divided retrospectively into four groups based upon post-surgical, sustained, basal blood oxygen (chronically hypoxaemic; P(a,O2), 17.3 +/- 0.5 mmHg; n = 8), glucose (chronically hypoglycaemic; blood glucose, 0.49 +/- 0.03 mmol l(-1); n = 6) and acid-base (chronically acidaemic; pH(a), 7.25 +/- 0.01; n = 5) status. Values for compromised fetuses were -2 S.D. from a group of control (n = 14) fetuses. At 130 +/- 4 days, a 1 h episode of acute, isocapnic hypoxaemia (9 % O(2) in N(2), to reduce carotid P(a,O2) to 12 +/- 1 mmHg) was induced in all fetuses by reducing the maternal inspired O(2) fraction (F(I,O2)). Fetal cardiovascular variables were recorded at 1 s intervals throughout the experimental protocol and arterial blood samples taken at appropriate intervals for biophysical (blood gases, glucose, lactate) and endocrine (catecholamines, vasopressin, cortisol, ACTH) measures. During acute hypoxaemia all fetuses elicited hypertension, bradycardia and femoral vasoconstriction. However, prevailing fetal compromise altered the cardiovascular and endocrine responses to a further episode of acute hypoxaemia, including: (1) enhanced pressor and femoral vasoconstriction; (2) greater increments in plasma noradrenaline and vasopressin during hypoxaemia; and (3) basal upward resetting of hypothalamic-pituitary-adrenal axis function. Only chronically hypoxaemic fetuses had significantly elevated basal concentrations of noradrenaline and enhanced chemoreflex function during acute hypoxaemia. These data show that prevailing adverse intrauterine conditions alter the capacity of the fetus to respond to a subsequent episode o

Topics: Acid-Base Equilibrium; Acidosis; Acute Disease; Adrenocorticotropic Hormone; Animals; Blood Gas Analysis; Blood Glucose; Cardiovascular System; Catecholamines; Chemoreceptor Cells; Endocrine System; Female; Fetal Diseases; Fetus; Hemoglobins; Hindlimb; Hydrocortisone; Hydrogen-Ion Concentration; Hypoglycemia; Hypoxia; Lactic Acid; Pregnancy; Sheep; Vascular Resistance; Vasopressins

To evaluate the role of vasopressin in the renal changes during combined acute hypoxemia and acute hypercapnic acidosis, eight conscious female mongrel dogs prepared with controlled sodium intake at 80 meq/24 h for 4 days were studied in one of the following six protocols: acute hypoxemia (80 min, arterial PO2 34 +/- 1 mmHg) followed by combined acute hypoxemia and hypercapnic acidosis (40 min, arterial PO2 35 +/- 1 mmHg, arterial PCO2 58 +/- 1 mmHg, pH = 7.20 +/- 0.01) during 1) intrarenal vehicle at 0.5 ml/min (N = 8); or 2) intrarenal infusion of vasopressin V1-receptor antagonist [d(CH2)5Tyr(Me)]AVP at 5 ng.kg-1.min-1 (N = 5); and with normal gas exchange during 3) intrarenal vasopressin at 0.05 mU.kg-1.min-1 (N = 8); 4) simultaneous infusion of intrarenal vasopressin and [d(CH2)5Tyr(Me)]AVP, 5 ng.kg-1.min-1 (N = 4); 5) intrarenal [d(CH2)5Tyr(Me)]AVP, 5 ng.kg-1.min-1 (N =4); and 6) intrarenal vehicle at 0.5 ml/min (N = 7). Intrarenal infusion of a subpressor dose of vasopressin resulted in a transient decrease in glomerular filtration rate and effective renal plasma flow over the first 20 min of infusion, suggesting that vasopressin induced nonsustained vasoconstriction of the renal vasculature. Intrarenal administration of [d(CH2)5Tyr-(Me)]AVP failed to block the fall in glomerular filtration rate or effective renal plasma flow when renal arterial blood vasopressin levels were elevated by intrarenal administration of exogenous vasopressin or by elevated systemic arterial endogenous circulating vasopressin during combined acute hypoxemia and hypercapnic acidosis. These data suggest that vasopressin (V1-receptor stimulation) does not play an important role in the renal vasoconstriction during combined acute hypoxemia and hypercapnic acidosis in conscious dogs.

Topics: Acidosis; Animals; Arginine Vasopressin; Dogs; Female; Hypercapnia; Hypoxia; Injections; Kidney; Receptors, Angiotensin; Receptors, Vasopressin; Reference Values; Renal Circulation; Vasopressins

It has been suggested that the substantial rise in fetal plasma arginine vasopressin (AVP) during intrauterine hypoxia/asphyxia reflects decreases in PaO2 and/or pHa; however, the components of these "stresses," i.e. PO2, PCO2, and pH, have not been controlled. Recently, only modest increases in fetal AVP secretion were seen during hypoxia independent of changes in pH and PCO2. Since the independent effects of metabolic acidosis on fetal AVP secretion are unknown, we induced acute metabolic acidemia in fetal sheep at 137 +/- 4 (mean +/- SD) days gestation with 1 M NH4Cl, while monitoring mean arterial pressure, heart rate, PaO2, PaCO2, pHa, plasma osmolality, and blood concentrations of electrolytes, AVP, dopamine, norepinephrine, and epinephrine. Mean arterial pressure, PaO2, PaCO2, and plasma osmolality and sodium were unchanged; pHa decreased from 7.37 +/- 0.01 to 7.04 +/- 0.05 (p less than 0.05) during NH4Cl and did not return to control levels until 24 h later. AVP increased from 2.85 +/- 0.23 to 5.26 +/- 1.11 microU/ml (p less than 0.05) at the time of maximum acidosis, correlating with the fall in pHa (r = -0.67, (p = 0.001); however, after stopping NH4Cl, AVP returned to baseline levels although pHa remained less than 7.15. In control studies using the same osmolar load, volume, and rate of infusion, AVP levels were unchanged. Only epinephrine was significantly (p less than 0.05) elevated during acidosis, but did not correlate with pHa or plasma AVP. Marked metabolic acidemia appears to have little or no effect on fetal AVP secretion, and fetal catecholamine secretion is variable.

Topics: Acidosis; Ammonium Chloride; Amniotic Fluid; Animals; Arginine Vasopressin; Blood Gas Analysis; Catecholamines; Dopamine; Epinephrine; Female; Fetus; Hypoxia; Norepinephrine; Pregnancy; Sheep; Vasopressins

Vasopressin (VP) has been found in the cerebrospinal fluid (CSF) of several species of animals. Although it is known that hemorrhage, hypertonicity of body fluid, hypoxia, and hypercapnia all increase VP in plasma, little is known regarding the stimuli that cause the secretion of VP into the CSF. We therefore performed several studies to examine whether stimuli capable of increasing plasma levels of VP can also increase VP in the CSF of anesthetized dogs. We found that hemorrhage, intracerebroventricular infusion of hypertonic artificial CSF, hypoxia, and hypercapnia all produced increases in the concentration of VP in plasma and in CSF, but the time courses and the magnitude of the increases in the two compartments were different. In addition, an i.v. infusion of hypertonic saline or of hydrochloric acid produced an increase in plasma VP without significantly changing CSF VP. Thus, although the secretion of VP into plasma and CSF may be influenced by the same stimuli, changes in one compartment do not necessarily correlate with changes in the other. Taken together, our results are consistent with the hypothesis that the plasma and CSF VP may derive from different sources.

Topics: Acidosis; Animals; Cerebrospinal Fluid; Dogs; Hemorrhage; Hypercapnia; Hypoxia; Infusions, Parenteral; Injections, Intraventricular; Saline Solution, Hypertonic; Vasopressins

Topics: Acidosis; Anti-Ulcer Agents; Blood Coagulation Disorders; Enteral Nutrition; Humans; Intensive Care Units; Intubation, Gastrointestinal; Peptic Ulcer Hemorrhage; Plasma Substitutes; Somatostatin; Stomach Ulcer; Stress, Physiological; Vasopressins

Hypoxia and hypercapnia have been shown to cause an increase in the concentration of vasopressin in plasma, but their effects on vasopressin in cerebrospinal fluid (CSF) are not known. In addition, the effect of metabolic acidosis on plasma and CSF vasopressin has not been reported. In this study, plasma and CSF vasopressin levels were measured in anesthetized dogs subjected to either hypoxia, hypercapnia, or metabolic acidosis. Rate and depth of respiration were closely regulated with the aid of muscle paralysis and mechanical ventilation. Vasopressin increased markedly in both plasma and CSF during severe hypoxia (10% O2) and during hypercapnia (10% CO2) but did not change during either mild (15% O2) or moderate (12.5% O2) hypoxia. Although mild hypoxia by itself did not affect either plasma or CSF vasopressin, it did potentiate the increase in plasma and CSF vasopressin that was induced by severe hypercapnia, thus suggesting that hypoxia and hypercapnia may exert synergistic effects on vasopressin secretion. Metabolic acidosis produced by slow intravenous infusion of 1 N hydrochloric acid decreased arterial pH to values comparable to those induced by hypercapnia and increased vasopressin in plasma; CSF vasopressin was unchanged. These results are consistent with the concept that the source of vasopressin secreted into plasma may be different from that secreted into CSF.

Topics: Acidosis; Animals; Dogs; Hypercapnia; Hypoxia; Vasopressins

A decrease in extracellular pH is well known to inhibit vasopressin stimulated water flow in the toad bladder. It remains unclear whether this inhibition is the result of the effect of extracellular pH per se or the consequence of altered intracellular pH. In the present study we evaluated the effect of several maneuvers capable of altering intracellular pH on vasopressin or cyclic AMP stimulated water flow in the toad bladder in the absence of alterations of extracellular pH. In the presence of a normal extracellular pH, bladders subjected to a high partial pressure of CO2 or bladders from acidotic toads had a significant decrease in vasopressin or cyclic AMP stimulated water flow as compared to controls. We also examined the effect of maneuvers capable of increasing intracellular pH on vasopressin and cyclic AMP stimulated water flow. Intracellular alkalosis was induced by exposing the bladders in vitro to NH4Cl at pH 8 or to acetazolamide. Both maneuvers resulted in a significant decrease in vasopressin, but not in cyclic AMP stimulated water flow. Bladders removed from alkalotic toads, incubated in a normal extracellular pH also showed a decrease in AVP stimulated water flow. Intracellular muscle pH assessed with phosphorus nuclear magnetic resonance, was not different among bladders from control, acidotic and alkalotic toads. It is concluded that alterations of intracellular pH, in the absence of alterations of extracellular pH, are important in regulation of water transport in the toad bladder in response to vasopressin or cyclic AMP. In addition, metabolic acidosis or alkalosis alters AVP or cyclic AMP stimulated water flow by a mechanism independent of the intracellular pH.

Topics: Acetazolamide; Acid-Base Equilibrium; Acidosis; Alkalosis; Animals; Biological Transport; Body Water; Bufonidae; Cyclic AMP; Hydrogen-Ion Concentration; Hypercapnia; In Vitro Techniques; Urinary Bladder; Vasopressins

Topics: Acidosis; Female; Fetal Distress; Humans; Hypoxia; Pregnancy; Vasopressins

Acidosis inhibits the hydroosmotic response to vasopressin. Since prostaglandins are known to modulate vasopressin-stimulated water flow we investigated the role of endogenous prostaglandin E2(PGE2) production in the pH-dependent response of the toad urinary bladder to vasopressin. Graded acidification of the serosal medial resulted in a progressive decline in vasopressin-stimulated water flow from 26.6 +/- 0.5 mg/min at pH 8.4 to 1.7 +/- 0.6 at pH 6.9. In these bladders basal PGE2 synthesis increased from 5.09 +/- 0.51 pmol/min per g hemibladder at pH 8.4 to 18.8 +/- 2.8 at pH 6.9. The addition of that concentration of PGE2 produced by the bladder at pH 7.4 (4 nM) to bladders at pH 8.4 resulted in 62-71% of the inhibition usually seen at pH 7.4; these data suggest that basal PGE2 production per se and not other products of prostaglandin synthesis or other pH-dependent events is responsible for the effect of acidosis. Preincubation with prostaglandin synthesis inhibitors reversed in major part the effect of serosal acidification on the response to submaximal concentrations of vasopressin and completely abolished the effect of pH on near maximal concentrations of the hormone. An increase in PGE2 synthesis after vasopressin was not seen at any pH. These studies establish that increased basal PGE2 synthesis plays a critical role in the pH dependence of the hydroosmotic response to vasopressin and demonstrate that factors that modulate the response to vasopressin may exert this effect by changing the basal rate of prostaglandin synthesis.

Topics: Acidosis; Animals; Bufo marinus; Dinoprostone; Female; Hydrogen-Ion Concentration; Osmosis; Prostaglandins E; Urinary Bladder; Vasopressins

Topics: Acid-Base Imbalance; Acidosis; Alkalosis; Animals; Body Water; Bucladesine; Bufo marinus; Drug Interactions; Female; Indomethacin; Male; Urinary Bladder; Vasopressins

The administration of a vasopressor in the presence of hypovolemia results in a severe acidosis which may be fatal if continued.

Topics: Acidosis; Adult; Blood Volume; Female; Humans; Lactates; Male; Middle Aged; Shock; Vasoconstrictor Agents; Vasopressins

The renal response of the fetal lamb to repeated complete occlusion of the umbilical cord was studied in nine chronically instrumented animals. Five episodes of occlusion of the umbilical cord, each lasting for two minutes, produced a twofold rise in fetal urine osmolality and sodium, chloride, and potassium concentrations. Output of urine and glomerular filtration rate remained essentially unchanged while free water clearance decreased from a control of +0.10 to -0.02 ml. per kilogram per minute at the end of the fifth episode. Electrolyte concentrations in urine remained elevated for at least two hours following the occlusions. In addition to changes in urine composition, there was a 50- to 200-fold increase in the fetal plasma concentration of vasopressin. These studies indicate that complete interruption of the umbilical circulation, even though of short duration, produces disturbances in fetal renal function that can lead to loss of electrolytes in the urine. They provide an explanation for the low sodium levels reported in asphyxiated newborn infants in renal failure.

Topics: Acid-Base Equilibrium; Acidosis; Animals; Blood; Blood Pressure; Carbon Dioxide; Constriction; Electrolytes; Female; Fetal Diseases; Fetal Hypoxia; Fetus; Glomerular Filtration Rate; Heart Rate; Hydrogen-Ion Concentration; Kidney; Osmolar Concentration; Oxygen; Pregnancy; Sheep; Umbilical Cord; Urine; Vasopressins

Diuretic features of 1,4-dimorpholino-7-phenylpyrido[3,4-d]pyridazine (DS-511) were studied in rats and mice. DS-511 was similar in diuretic effect to that of hydrochlorothiazide (HC) in both species, but was more water diuretic and less potassium-releasing than HC. After oral administration of DS-511 to rats the diuretic effect promptly appeared and lasted for 4 to 5 h. These patterns on onset and duration were similar to those of furosemide and acetazolamide (AZ). DS-511 was effective in experimentally induced acidotic and alkalotic rats. When DS-511 was used in combinations with other diuretics such as HC, AZ and triamterene at their maximum effective doses, urine volume and sodium excretion further increased, but potassium did not. Diuretic activity of DS-511 was not reduced by daily oral administration for 10 days to rats. In rats DS-511 reversed antidiuretic hormone (ADH)-induced antidiuresis. These findings suggest that DS-511 differs in mode and/or site of action from the known diuretics.

Topics: Acidosis; Alkalosis; Animals; Diuretics; Dose-Response Relationship, Drug; Drug Administration Schedule; Drug Interactions; Electrolytes; Male; Mice; Morpholines; Pyridazines; Rats; Time Factors; Vasopressins

Recent studies have shown that chronic hypotonic volume expansion (HVE) induced by administration of vasopressin and water stimulates distal hydrogen ion secretion and thereby (a) permits dogs with HCl-acidosis to restore acid-base equilibrium to normal despite continued acid feeding and (b) permits normal dogs to conserve filtered bicarbonate quantitatively despite the natriuresis induced by water retention. To examine whether these effects of chronic HVE are mediated by augmented mineralocorticoid secretion, urinary and plasma aldosterone levels were monitored during prolonged administration of vasopressin. In HCl-fed animals, the HVE-induced rise in plasma [HCO3] (from 13.8 to 21.3 meq/liter) was associated with a rise in aldosterone excretion from 0.45 to 0.88 mug/day (P less than 0.02). In normal animals, in which plasma [HCO3] remained stable during HVE (21.9 vs. 20.0 meq/liter), aldosterone excretion rose from 0.51 to 2.28 mug/day (P less than 0.02) and plasma aldosterone concentration rose from 8.1 to 39.8 ng/100 ml (P less than 0.01). Vasopressin and water were also administered to adrenalectomized animals maintained on glucocorticoids and a slightly subphysiologic replacement schedule of mineralocorticoids. In the HCl-fed adrenalectomized group, plasma [HCO3], instead of rising to normal, showed no significant change (16.9 vs. 15.0 meq/liter). In the non-HCl-fed adrenalectomized group, plasma [HCO3], rather than remaining stable, fell significantly (20.3 vs 16.5 meq/liter, P less than 0.1). Two conclusions can be drawn from this study: (a) the well-known inhibitory effect of volume expansion on aldosterone secretion can be overridden by a potent stimulatory effect on the adrenal produced by severe chronic hypotonicity, and (b) the response of plasma [HCO3] observed during severe chronic HVE is mediated by augmented mineralocorticoid secretion. These findings, furthermore, offer a possible explanation for the puzzling observation that plasma [HCO3] in patients with the syndrome of inappropriate antidiuretic hormone secretion is maintained at normal levels even in the face of severe hyponatremia.

Topics: Acid-Base Equilibrium; Acidosis; Adrenal Glands; Adrenalectomy; Aldosterone; Animals; Bicarbonates; Blood Volume; Dogs; Extracellular Space; Female; Hyponatremia; Kidney; Vasopressins; Water

Acidic media have been reported to inhibit the hydro-osmotic effect of vasopressin in toad bladders, probably through inhibition of the cyclic AMP system. However, the mechanism of inhibition of the cyclic AMP system is controversial. Therefore, that inhibitory mechanism was further investigated in rat kidneys. The antidiuretic response to vasopression was significantly inhibited in animals with metabolic acidosis. The inhibition of the antidiuretic response was associated with a smaller than normal increase of urinary excretion of cyclic AMP after the iv injection of vasopressin. In in vitro experiments, both the increase of cyclic AMP concentration in renal medullary slices and the activation of adenylate cyclase in medulla by vasopressin were significantly less in acidic than in control media. These findings suggest that medabolic acidosis inhibits the antidiuretic effect of vasopressin by inhibiting the vasopressin-dependent cyclic AMP system in the kidney. Acidic media also inhibited cyclic AMP-phosphodiesterase. These dual effects of acidosis on adenylate cyclase and cyclic AMP-phosphodiesterase may explain the conflicting findings observed in the experiments on toad bladders.

Topics: 3',5'-Cyclic-AMP Phosphodiesterases; Acidosis; Adenylyl Cyclases; Ammonium Chloride; Animals; Bicarbonates; Blood; Cyclic AMP; Hydrogen-Ion Concentration; Inulin; Kidney; Kidney Medulla; Rats; Time Factors; Vasopressins

The role of hyperthermia in the absence of infection has been investigated in the pregnant baboon. Twenty-three near term animals were used. Catheters were placed in maternal and fetal arteries and thermocouples implanted in maternal colon and fetal esophagus. Maternal temperature was raised to between 41 and 42 degrees Centigrade (C.), by applying external heat. The temperature gradient between fetus and mother (delta T F-M) was 0.47 degree C. under steady-state conditions with maternal temperature at 38 degrees C. and rose to 0.75 degree C. at 42 degrees C. Hyperthermia caused a twofold increase in uterine activity; a metabolic acidosis developed in the mother and a profound acidosis and hypoxia developed in the fetus. There was also a marked fall in blood pressure and an increase in heart rate in both mother and fetus; late deceleration of the fetal heart rate occurred at a higher oxygen level and pHa than has been observed under normothermic conditions.

Topics: Acidosis; Animals; Arrhythmias, Cardiac; Body Temperature; Female; Fetal Death; Fetal Diseases; Fetal Heart; Fever; Haplorhini; Heart Rate; Hypotension; Hypoxia; Labor, Obstetric; Oxytocin; Papio; Pregnancy; Pregnancy Complications; Vasopressins

The infiltration of a vasoconstrictor causes bleeding to diminish in the surgical field. Adrenalin is such a vasoconstrictor, but because of its metabolic action, acidosis develops in the tissue followed by decreased oxygen tension, a reactive hyperemia. This can of course cause postoperative hemorrage and edema.

Topics: Acidosis; Body Temperature; Epinephrine; Hemostasis; Humans; Hyperemia; Jaw; Oral Hemorrhage; Ornithine; Oxygen; Surgery, Oral; Thermography; Vasopressins

Topics: Acidosis; Alcoholism; Blood; Depression, Chemical; Diuresis; Ethanol; Gout; Humans; Lactates; Magnesium; Magnesium Deficiency; Osmolar Concentration; Uric Acid; Vasopressins

Topics: Acid-Base Equilibrium; Acidosis; Ammonia; Animals; Dehydration; Dogs; Extracellular Space; Glutamates; Glutaminase; Glutamine; Hydrogen-Ion Concentration; Kidney; Kidney Cortex; Kidney Medulla; Male; Phosphates; Rats; Vasopressins; Water

Investigation of a patient with hypercalcaemia, hypophosphataemia, and nephrocalcinosis failed to lead to a clear diagnosis. Neither primary hyperparathyroidism nor primary incomplete renal tubular acidosis could explain all the biochemical features, and it seems that more than one fundamental abnormality may have been present.

Topics: Acidosis; Acidosis, Renal Tubular; Adolescent; Ammonium Chloride; Calcium; Calcium, Dietary; Diagnosis, Differential; Humans; Hydrogen-Ion Concentration; Hypercalcemia; Hyperparathyroidism; Male; Nephrocalcinosis; Osmolar Concentration; Phosphates; Urine; Vasopressins

Balance studies have been carried out to evaluate the influence of vasopressin-induced volume expansion on acid-base equilibrium in normal dogs and in dogs with steady-state metabolic acidosis induced by the administration of 5-7 mmoles/kg per day of hydrochloric acid.Hypotonic expansion in dogs with metabolic acidosis (mean plasma bicarbonate concentration 14 mEq/liter) produced a marked increase in renal acid excretion that restored plasma bicarbonate concentration to normal (20-21 mEq/liter) despite continued ingestion of acid. When water was restricted during the vasopressin period, and fluid retention thus prevented, no increase in acid excretion or plasma bicarbonate concentration occurred. From these findings we conclude that hypotonic expansion is a potent stimulus to renal hydrogen ion secretion and greatly facilitates the renal removal of an acid load. Normal dogs subjected to expansion demonstrated no change in net acid excretion or in plasma bicarbonate concentration even in the face of a marked diuresis of sodium and chloride and a reduction in plasma sodium concentration to approximately 110 mEq/liter. The animals did, however, regularly lose potassium, a finding that clearly indicates an acceleration of distal sodiumcation exchange. On the basis of these observations, and the findings in the expanded acidotic dogs, we suggest that in the expanded normal dogs acceleration of sodium-hydrogen exchange was responsible for preventing a bicarbonate diuresis and for stabilizing plasma bicarbonate concentration. These studies clearly demonstrate that chronic hypotonic expansion exerts a major influence on the renal regulation of acid-base equilibrium. The exact nature of the mechanism responsible for the increase in sodium-hydrogen exchange during hypotonic expansion remains to be determined.

Topics: Acid-Base Equilibrium; Acidosis; Animals; Bicarbonates; Blood Volume; Body Weight; Carbon Dioxide; Chlorides; Diuresis; Dogs; Female; Hydrochloric Acid; Hydrogen-Ion Concentration; Hypotonic Solutions; Kidney; Osmolar Concentration; Potassium; Sodium; Sodium Chloride; Vasopressins

Topics: Acidosis; Animals; Blood Pressure; Cardiac Output; Dogs; Female; Heart; Hydrogen-Ion Concentration; Hypoxia; Isoproterenol; Male; Norepinephrine; Sympathomimetics; Vasopressins

Topics: Acidosis; Acidosis, Respiratory; Aorta; Blood Vessels; Carbon Dioxide; Cats; Dogs; Muscle Proteins; Norepinephrine; Pharmacology; Rabbits; Research; Reserpine; Tyramine; Vasopressins

Topics: Acidosis; Acidosis, Renal Tubular; Amino Acids; Humans; Kidney Diseases; Polyuria; Vasopressins

Topics: Acidosis; Antidiuretic Agents; Blood Chemical Analysis; Blood Glucose; Diabetes Insipidus; Diabetes Insipidus, Neurogenic; Diabetes Mellitus; Diabetic Ketoacidosis; Humans; Vasopressins; Water-Electrolyte Balance

Topics: Acidosis; Child; Diabetes Insipidus; Humans; Infant; Kidney; Vasopressins