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Hormonal changes during exercise is of growing interest because of their role in adaptation, and performance. The production of amino acids (AA) due to the degradation of muscle protein increases during exercise and some AA may be utilized for energy expenditure or as hormonal secretogogues. Thus, one can propose a strategy to reduce muscle protein breakdown and regulate hormones involved in energy metabolism by dietary AA supplementation.We assessed the effects of glutamate-arginine salt (AGs) ingestion on exercise-induced hormonal alterations in highly trained cyclists (age 18-22 yrs). Using an indwelling catheter, we collected multiple blood samples at rest, during warm up, during and after an intense exercise session. Plasma growth hormone (hGH), insulin and Cortisol were measured by radioimmunoassay.As reported in previous studies, we observed a marked increase in plasma hGH and Cortisol levels during and after exercise in the placebo (Pl) condition as well as a slight decrease in insulin concentration. In addition, we found that the ingestion of AGs had significant effects on some dynamic hormonal changes. AGs had no effect on resting plasma levels of hGH, insulin or Cortisol. However, the marked elevation in Cortisol and hGH during and after exercise in the placebo condition, was greatly diminished when subjects ingested AGs. Our results show that AGs can modify exercise-induced hormonal changes and raise the possibility that it may be used to alter energy metabolism during endurance exercise.

The antisecretory peptide YY (PYY) inhibits jejunal secretion through and inhibitory protein (Gi), whereas sodium fluoride (NaF) is a potent activator of G-proteins. This work was conducted to characterize the role of NaF in the antisecretory effect of PYY. For this purpose, electrogenic chloride secretion was assessed by measuring the in vitro variations in short-circuit current (Isc) due to alterations in ionic transport, using Ussing chambers. Results: 1) NaF induced a transient increase in Isc at concentrations exceeding 5 mM. 2) 2 mM NaF inhibited the antisecretory effect of 0.1 µM PYY and of its analog P915. 3) stimulation of secretion by forskolin and dbcAMP was halved in the presence of 2 mM NaF. 4) Inhibition of protein kinase C by 0.1 mM bisindolylmaleimide caused a sustained increase in Isc in the presence of 5 mM NaF. In conclusion, these results confirm that PYY inhibits electrogenic chloride secretion and show that NaF stimulates it, and suggest that NaF reduces PYY-induced inhibition via a G-dependent and a G-independent functional pathway.

Glicentin (GLIC) and oxyntomodulin (OXM) arereleased from the ileum and colon during digestion. Bothhormones reduce fluid and proton secretion in thestomach. The luminal concentration of sodium andchloride underlying the nutrient absorption, the effectof OXM on electrolyte transport through the smallintestine, was assessed in vivo using ligated loops andin vitro using Ussing chambers. In vivo , a zero transport state, estimated by the net water,chloride, and sodium fluxes, was observed when an 80 mMNaCl normoosmolar solution (274 mosm) was administeredintraluminally. Active secretion was observed with hyperosmotic challenge (474 mosm). Theamplitude of this active secretion increased 2.5- to3-fold when an electrogenic challenge (NaCl 40 mM) wassubstituted to the hyperosmotic one. OXM (800 fmol/ml plasma) did not modify the basal transport inthe duodenum or in the jejunum (t = 45 min). When activesecretion was induced by the hyperosmotic challenge, OXM(200 fmol/ml plasma) had no effect on duodenal or jejunal transport (t = 50 min). When activesecretion was induced by an electrogenic challenge, OXM(300 fmol/ml plasma) preferentially reduced thehydromineral transport in jejunum. In vitro , OXM also induced a reduction in the ion transporttowards the jejunal lumen (EC50= 20 pM), theamplitude of which depended upon the integrity of thetetrodotoxin-sensitive neurons. In conclusion, OXM wasable to reduce the large secretion induced in ratjejunum in vivo by an electrogenic gradient. In vitro,the antisecretory effect of OXM was partly mediated bythe neurons present in the intrajejunal wall.

The purpose of this study was to examine the effect of glutamate-arginine salt (AGs) or placebo (P1) on ammonemia during and after 1 hour exercise on sporting event bicycle under ergonomic device at 80% VO2max in 3 healthy male volunteers (age 18-25 years).Subjects were tested in three sessions, at rest after AGs and during exercise with placebo (PI) or AGs. The subjects were given 20 g of AGs or PI orally and 30 min later, exersised at 75-80% VO2max for 30 min. Blood samples were taken at 0, + 30, + 60, + 90, + 120 min after AGs and analyzed for ammonemia. Our results show a highly significant increase in plasma ammonia concentration during exercise. The magnitude of this increase was diminished when subjects were given AGs before the exercise session, suggesting that AGs may help reduce physiologic fatigue.