PANCREASTATIN MODULATES GLUCOSE-STIMULATED INSULIN-SECRETION FROM THEPERFUSED RAT PANCREAS

Pancreastatin is known to be produced in islet B cells and to inhibit insulin secretion. In this study, we examined whether the peptide affe cts insulin secretion from the perfused rat pancreas during raising or lowering the glucose concentration within the physiological range, We found that synthetic porcine pancreastatin (15 nmol L(-1)) significan tly inhibited the first phase (5 min) of insulin release induced by ra ising the glucose concentration from 4.2 to 8.3 mmol L(-1) (Pi 0.05) w ithout affecting the second phase. Furthermore, the fall in insulin se cretion induced by lowering the glucose concentration from 8.3 to 5.5 mmol L(-1) was significantly exaggerated in presence of pancreastatin during the first 5 min (P < 0.05). In contrast. pancreastatin did not affect the inhibition of insulin secretion induced by either the alpha (2)-adrenoceptor agonist. clonidine (2 nmol L(-1)), or the P-1-purinoc eptor (A(1)-subtype) agonist. N-6(+) -phenylisopropyladenosine (D) PIA ) (1.65 mu mol L(-1)). in conclusion, our results show that pancreasta tin is a modulator oi the early changes in insulin secretion alter inc rease or decrease of the glucose concentration within the physiologica l range, This suggests that pancreastatin is a modulator of glucose-st imulated insulin secretion.