ARGININE-INDUCED PANCREATIC HORMONE-SECRETION DURING EXERCISE IN RATS

The aim of the present investigation was to 1) determine whether argin ine-induced pancreatic hormone secretion can be modified during an exe rcise bout, and 2) verify whether the sectioning of the hepatic branch of the vagus nerve can alter the arginine-induced insulin and glucago n secretion during exercise in rats. To this end, we studied the effec ts of an intraperitoneal injection of arginine (1 g/kg body mass) duri ng an exercise bout (30 min, 26 m/min, 0% grade) on the pancreatic hor mone responses. These effects were determined in one group of sham-ope rated exercising rats and compared with three control groups: one grou p of resting rats, one group of saline-injected exercising rats, and o ne group of hepatic-vagotomized exercising rats. Five minutes after th e injection of arginine, significant (P < 0.05) increases in insulin, glucagon, and C-peptide concentrations were observed in exercising as well as in resting rats. These responses were not, however, altered by the hepatic vagotomy and/or by the exercise bout. It is concluded tha t arginine is a potent stimulus of pancreatic hormone secretion during exercise, even though the sympathoadrenal system is activated. These results also indicate that a hepatic vagotomy does not seem to influen ce arginine-induced hormonal pancreatic responses and question the rol e of the putative hepatic arginoreceptors in the control of the pancre atic hormone secretion during exercise.