MODULATION OF INSULIN-SECRETION AND CA-45(2-STIMULATED PANCREATIC-ISLETS() EFFLUX BY DOPAMINE IN GLUCOSE)

1. The effect of dopamine on calcium efflux and insulin secretion is e xamined in the present study. For this purpose, islets isolated from a dult Wistar rats were perfused or incubated at 37 degrees C for 60 min . 2. The results obtained from perfused islets indicate that 100 mu M dopamine, in the presence of 5.6 mM glucose, increases insulin secreti on and causes a modest elevation of Ca-45(2+) efflux. However, glucose stimuli (from 5.6 to 16.7 mM) provoked an unexpected reduction of ins ulin release, with no alteration in calcium efflux, when 100 mu M dopa mine was present in the perfusion medium. 3. Similar findings were obt ained in incubated islets when the prolonged effect of dopamine was in vestigated. 4. The observations described above led us to conclude tha t bioactive amines might play an important role in the modulation of t he glucose-induced insulin secretion.