pituitrin and Glycosuria

Diabetic nephropathy represents a major complication of diabetes mellitus (DM), and the origin of this complication is poorly understood. Vasopressin (VP), which is elevated in type I and type II DM, has been shown to increase glomerular filtration rate in normal rats and to contribute to progression of chronic renal failure in 5/6 nephrectomized rats. The present study was thus designed to evaluate whether VP contributes to the renal disorders of DM. Renal function was compared in Brattleboro rats with diabetes insipidus (DI) lacking VP and in normal Long-Evans (LE) rats, with or without streptozotocin-induced DM. Blood and urine were collected after 2 and 4 weeks of DM, and creatinine clearance, urinary glucose and albumin excretion, and kidney weight were measured. Plasma glucose increased 3-fold in DM rats of both strains, but glucose excretion was approximately 40% lower in DI-DM than in LE-DM, suggesting less intense metabolic disorders. Creatinine clearance increased significantly in LE-DM (P < 0.01) but failed to increase in DI-DM. Urinary albumin excretion more than doubled in LE-DM but rose by only 34% in DI-DM rats (P < 0.05). Kidney hypertrophy was also less intense in DI-DM than in LE-DM (P < 0.001). These results suggest that VP plays a critical role in diabetic hyperfiltration and albuminuria induced by DM. This hormone thus seems to be an additional risk factor for diabetic nephropathy and, thus, a potential target for prevention and/or therapeutic intervention.

Topics: Albuminuria; Animals; Creatinine; Diabetes Insipidus; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Glomerular Filtration Rate; Glycosuria; Hypertrophy; Kidney; Kidney Failure, Chronic; Male; Nephrectomy; Organ Size; Rats; Rats, Brattleboro; Rats, Long-Evans; Vasopressins

In diabetes mellitus (DM), the high urine flow rate suggests that urinary concentrating capacity is impaired. However, several studies have shown that vasopressin is elevated in DM and the consequences of this elevation have not yet been characterized. This study reevaluated renal function and water handling in male Wistar rats with Streptozotocin-induced DM, and in control rats. During five weeks after induction of DM, urine was collected in metabolic cages and a blood sample was drawn during the third week. Control rats (CONT) were studied in parallel. On week 3, urine flow rate was tenfold higher in DM than in CONT rats and urinary osmolality was reduced by half along with a markedly higher osmolar excretion (DM/CONT = 5.87), due for a large part to glucose but also to urea (DM/CONT = 2.49). Glucose represented 52% of total osmoles (90.3 +/- 6.5 mmol/d out of 172 +/- 14 mosm/d). Free water reabsorption was markedly higher in DM rats compared to CONT (326 +/- 24 vs 81 +/- 5 ml/d). In other rats treated in the same way, urinary excretion of vasopressin was found to be markedly elevated (15.1 +/- 4.1 vs 1.44 +/- 0.23 ng/d). In DM rats, glucose concentration in urine was 17 fold higher than in plasma, and urea concentration 14 fold higher. Both urine flow rate and free water reabsorption were positively correlated with the sum of glucose and urea excretions (r = 0.967 and 0.653, respectively) thus demonstrating that the urinary concentrating activity of the kidney increased in proportion to the increased load of these two organic solutes. These results suggest that vasopressin elevation in DM contributes to increase urinary concentrating activity and thus to limit water requirements induced by the metabolic derangements of DM. The possible deleterious consequences of sustained high level of vasopressin in DM are discussed.

Topics: Animals; Blood Glucose; Body Weight; Creatinine; Diabetes Mellitus, Experimental; Diuresis; Drinking Behavior; Glucagon; Glycosuria; Kidney Concentrating Ability; Male; Potassium; Rats; Rats, Wistar; Sodium; Urea; Vasopressins

Topics: Adult; Blood Glucose; Blood Urea Nitrogen; Blood Volume; Burns; Diabetes Complications; Diuresis; Female; Glycosuria; Humans; Hypernatremia; Infusions, Parenteral; Male; Middle Aged; Nitrogen; Osmolar Concentration; Sepsis; Vasopressins; Water-Electrolyte Balance

Topics: Blood Glucose; Diabetes Mellitus; Diuresis; Glomerular Filtration Rate; Glycosuria; Humans; Kidney; Kidney Concentrating Ability; Kidney Function Tests; Kidney Tubules; Osmolar Concentration; Vasopressins; Water Deprivation; Water-Electrolyte Balance

1. The effect of intravenous infusions of various ions on the antidiuretic action of antidiuretic hormone has been studied in rats.2. Lithium (13 mmol/l.) reversibly inhibits the antidiuretic responses. Similar concentrations of potassium, rubidium, strontium, magnesium, choline and calcium do not. Lithium has a similar effect on the antidiuretic activity of oxytocin.3. The inhibition is not simply related to blood nor whole body lithium concentrations.4. Lithium (2 mmol/l.) in contact with the serosal surface also inhibits the transport of water facilitated by either 0.5 U/l. antidiuretic hormone or 1.1 mmol/l. cyclic adenosine monophosphate in the isolated toad bladder.5. Choline (2 mmol/l.) on the serosal surface also inhibits the transport of water facilitated by vasopressin in the toad bladder.

Topics: Animals; Bufo marinus; Choline; Cyclic AMP; Glucose; Glycosuria; In Vitro Techniques; Kidney; Kidney Cortex; Kidney Medulla; Lithium; Male; Osmolar Concentration; Oxytocin; Photometry; Potassium; Rats; Sodium; Spectrophotometry, Atomic; Time Factors; Urinary Bladder; Vasopressins

1. The fluid sacs and bladders of ten foetuses and the allantoic sacs of five foetuses were catheterized between 79 and 96 days gestational age and daily samples were withdrawn until lambs were born naturally at approximately 147 days. Maternal jugular plasma obtained daily allowed the nutritional status of each ewe to be regulated and monitored. All lambs were observed for 7 weeks, and at post-mortem no abnormalities were seen in those operated upon in utero.2. The osmolality, [Na(+)], [K(+)], [Cl(-)], [glucose], [fructose], [urea], [amino acid] and pH of all samples were measured.3. Foetal surgery seemed to affect the actual concentrations of some solutes, but gestational trends in foetal fluid composition were unaltered.4. Until about 7 days before birth the foetal urine osmolality, [Na(+)], [Cl(-)] and [fructose] decreased, its [urea], [amino acid] and pH remained relatively constant, and from about 120 days gestational age the [K(+)] increased. During the last 7 days there was a marked increase in the osmolality and the concentrations of all these solutes, and a decrease in pH.5. Entry of foetal urine into the fluid sacs tended to decrease the osmolality, [Na(+)], [K(+)], [Cl(-)] and [glucose] of both foetal fluids and the [amino acid] of allantoic fluid, and tended to increase the [fructose] and [urea] of both fluids and the [amino acid] of amniotic fluid.6. Changes in urine composition suggested large daily variations in the secretion of foetal antidiuretic hormone and also a rapid increase in its secretion during the last 7 days, and particularly the last 2-4 days before birth.7. Changes in the [Na(+)]/[K(+)] ratios of foetal urine and allantoic fluid were parallel during post-operative recovery, during the course of pregnancy and immediately before birth, and this was consistent with a simultaneous action of foetal plasma corticosteroids on the foetal kidneys and chorioallantois.8. Variations in the [fructose] of foetal urine and allantoic fluid were parallel to changes in their [Na(+)]/[K(+)] ratios and suggested an involvement of foetal corticosteroids in the regulation of the [fructose] of foetal plasma.9. Further evidence has been presented supporting the hypothesis that maternal induced foetal hypoglycaemia effects a relative increase in the secretion of foetal corticosteroids having an action on the chorioallantois. Also, high concentrations of maternal plasma corticosteroids may decrease the permeability of the placenta to glucose.

Topics: Amino Acids; Amniotic Fluid; Animals; Blood Glucose; Body Fluids; Chlorides; Extraembryonic Membranes; Female; Fetus; Fructose; Gestational Age; Glucocorticoids; Glycosuria; Hydrogen-Ion Concentration; Maternal-Fetal Exchange; Osmolar Concentration; Potassium; Pregnancy; Sheep; Sodium; Urea; Urinary Catheterization; Urine; Vasopressins

Topics: Adult; Animals; Blood Glucose; Diuresis; Dogs; Fasting; Female; Glomerular Filtration Rate; Glycosuria; Humans; Kidney; Kidney Concentrating Ability; Kidney Tubules; Male; Mannitol; Vasopressins

Topics: Blood Chemical Analysis; Carbon Dioxide; Chlorides; Diabetes Insipidus; Diabetes Mellitus; Glucose Tolerance Test; Glycosuria; Hematuria; Humans; Hydronephrosis; Hyperglycemia; Nitrogen; Polyuria; Potassium; Pseudomonas Infections; Sodium; Urea; Urinary Tract Infections; Urine; Urography; Vasopressins

Topics: Chlorides; Desoxycorticosterone; Drug Therapy; Glycosuria; Humans; Hydrocortisone; Kidney Function Tests; Male; Natriuresis; Polyuria; Prostatic Neoplasms; Urethral Stricture; Urine; Vasopressins

Topics: Diabetes Insipidus; Glycosuria; Kidney; Vasopressins