sodium-bicarbonate and Starvation

In this study, we investigated the relationship between MgSO(4) and luminescence in Vibrio fischeri under nutrient-starved conditions. When V. fischeri was cultured in an artificial seawater medium, the luminescence intensity was low relative to that observed under normal growth conditions. It decreased during the initial 14 h, and then increased slightly at 24 h. This regulation of luminescence was not dependent on the quorum-sensing mechanism, because the cell densities had not reached a critical threshold concentration. Under MgSO(4)-starved conditions, luminescence was not fully induced at 14 h, and decreased at 24 h. In contrast, induction of luminescence occurred under MgSO(4)-supplemented conditions, but MgSO(4) alone was insufficient to induce luminescence, and required NaHCO(3) or KCl. These results suggest that the luminescence of V. fischeri is controlled by an exogenous sulfur source under nutrient-starved conditions. In addition, they indicate that the induction of sulfur-dependent luminescence is regulated by the NaHCO(3) or KCl concentration.

Topics: Aliivibrio fischeri; Bacterial Proteins; Culture Media; Light; Luminescence; Luminescent Measurements; Magnesium Sulfate; Potassium Chloride; Quorum Sensing; Signal Transduction; Sodium Bicarbonate; Starvation

The mechanism behind the possible feedback regulation of pancreatic exocrine secretion is not well understood.. Thirteen minipigs were prepared with fistulas to the pancreatic duct and the duodenum. Peripheral venous blood was obtained for determination of secretin and cholecystokinin (CCK) levels. Four different experiments were performed: 1) diversion and reinfusion of pancreatic juice; 2) intraduodenal infusion of NaHCO3 solution, with the same volume, bicarbonate concentration, and osmolality as the collected pancreatic secretion, and reinfusion of pancreatic juice; 3) reinfusion of pancreatic secretion for 1 h before and 2 h after a meal; and 4) diversion of pancreatic secretion and intraduodenal infusion of NaHCO33 solutions before and after a meal.. Reinfusing pancreatic juice significantly decreased pancreatic juice volume and bicarbonate output and slightly decreased the level of secretin in plasma. Alternating infusions of substitute NaHCO3 and pancreatic juice did not change pancreatic output of bicarbonate and protein, nor did it change the CCK and secretin levels in plasma. Replacing pancreatic juice with intraduodenal NaHCO3 infusions during a meal did not significantly modify the pancreatic secretion of bicarbonate and protein or the hormonal levels in blood.. A negative feedback regulation of pancreatic exocrine secretion is present in starved minipigs. Duodenal acidity and plasma levels of secretin semm to be of importance, whereas duodenal enzyme activity and the level of CCK in plasma probably are not. A postprandial negative feedback regulation through duodenal enzymatic activity and release of CCK into blood could not be shown.

Topics: Animals; Cholecystokinin; Duodenal Diseases; Feedback; Food; Intestinal Fistula; Pancreas; Pancreatic Fistula; Pancreatic Juice; Secretin; Sodium Bicarbonate; Starvation; Swine; Swine, Miniature

1. The effect of an infusion of sodium beta-hydroxybutyrate on leucine and alanine metabolism was investigated in dogs starved for 12 h. To determine whether the metabolic changes produced by this infusion were due to the resultant alkalaemia the effect of an equimolar infusion of sodium bicarbonate was also studied. 2. The sodium beta-hydroxybutyrate infusion reduced alanine concentration as a result of a decrease in alanine production rate and an increase in alanine metabolic clearance rate. The sodium bicarbonate infusion induced a small decrease in alanine concentration which was due to an increased metabolic clearance rate. Alanine production rate showed no change. This demonstrates that the fall in alanine concentration after a sodium beta-hydroxybutyrate infusion is due both to a ketone-specific inhibitory effect on alanine production rate and an increased metabolic clearance rate caused by the alkalaemia. 3. Leucine concentration was increased after the ketone infusion due to a small increase in production rate and there was a small increase in the rate of leucine incorporation into protein. Alkalaemia had no effect on leucine concentration or metabolism.

Topics: 3-Hydroxybutyric Acid; Alanine; Animals; Bicarbonates; Dogs; Hydroxybutyrates; Ketone Bodies; Leucine; Metabolic Clearance Rate; Protein Biosynthesis; Sodium; Sodium Bicarbonate; Starvation

To non-anaesthetized rats starved for 3 days, [U-14C]acetone, NaH14CO3, L-[U-14C]lactate, [2-14C]acetate or D-[U-14C]- plus D-[3-3H]-glucose was injected intravenously. From the change in the plasma concentration of labelled acetone versus time after the injection, the metabolic clearance rate of acetone was calculated as 2.25 ml/min per kg body wt., and its rate of turnover as 0.74 mumol/min per kg. The extent and time course of the labelling of plasma glucose, lactate, urea and acetoacetate were followed and compared with those observed after the injection of labelled lactate, acetate and NaHCO3. The labelling of plasma lactate was rapid and extensive. Some 1.37% of the 14C atoms of circulating glucose originated from plasma acetone, compared with 44% originating from lactate. By deconvolution of the Unit Impulse Response Function of glucose, it was shown that the flux of C atoms from acetone to glucose reached a peak at about 100 min after injection of labelled acetone. In comparable experiments the transfer from lactate reached a peak at 14 min after the injection of labelled lactate. It was concluded that acetone is converted into lactate to a degree sufficient to account for the labelling of plasma glucose and is thus a true, albeit minor, substrate of glucose synthesis in starved rats.

Topics: Acetoacetates; Acetone; Animals; Bicarbonates; Blood Glucose; Gluconeogenesis; Lactates; Lactic Acid; Male; Rats; Rats, Inbred Strains; Sodium; Sodium Bicarbonate; Starvation; Urea