Arginine-induced pancreatic hormone secretion during exercise in rats

The aim of the present investigation was to 1) determine whether arginine-induced pancreatic hormone secretion can be modified during an exercise bout, and 2) verify whether the sectioning of the hepatic branch of the vagus nerve can alter the arginine-induced insulin and glucagon secretion during exercise in rats. To this end, we studied the effects of an intraperitoneal injection of arginine (1 g/kg body mass) during an exercise bout (30 min, 26 m/min, 0% grade) on the pancreatic hormone responses. These effects were determined in one group of sham-operated exercising rats and compared with three control groups: one group of resting rats, one group of saline-injected exercising rats, and one group of hepatic-vagotomized exercising rats. Five minutes after the 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 that 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 influence arginine-induced hormonal pancreatic responses and question the role of the putative hepatic arginoreceptors in the control of the pancreatic hormone secretion during exercise.