Effects of cholecystokinin octapeptide and carbachol on neonatal insulin secretory dynamics.
The effects of glucose, sulfated cholecystokinin-octapeptide (CCK-8), or carbachol on insulin secretory dynamics were studied in pancreatic islets isolated from 1- and 3-day-old neonatal rats. When challenged with glucose, 1-day islets responded with a definite first phase and elevated secretion during the latter part of the stimulation period; 3-day islets had a first phase and a rising, sustained second phase. The presence of stimulatory concentrations of CCK-8 or carbachol in addition to glucose caused dramatic changes in the release pattern in both islet populations. In 1-day islets, carbachol stimulated mainly first phase secretion whereas CCK-8 enhanced first phase release and produced a definite second phase response. The two secretagogues increased significantly both phases of release in 3-day islets with no differences between the two agents in their effects. These results indicate that CCK-8 and carbachol differentially stimulate neonatal insulin secretion, possibly through different steps in the stimulus-secretion pathway. They also suggest that the cellular mechanism for second phase release is present in 1-day islets and can be activated by CCK-8.
Fletcher
D J
DJ
Department of Anatomy and Cell Biology, School of Medicine, East Carolina University, Greenville, NC 27858.
Rowley
W H
WH
Brinn
J E
JE
D000818:Animals; D002217:Carbachol / Q000494:pharmacology*; D005947:Glucose / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D051381:Rats; D011919:Rats, Inbred Strains; D012844:Sincalide / Q000494:pharmacology*
D007328:Insulin; D002217:Carbachol; D005947:Glucose; D012844:Sincalide