Gradual delay in glucose-induced first phase insulin secretion by the pancreatic islets of 7 week-, 6 month-, and 1 year-old rats.
The temporal profiles of insulin secretion by isolated pancreatic islets of male Wistar rats with various ages up to 1-year-old were studied using high glucose, potassium (K+) depolarization, and arginine as secretagogues. In the islets of 6-month-old rats, the onset and peak of glucose-induced first phase of insulin release were delayed for 1 min compared to those of 7--week-old rats. The onset and peak were further delayed for 1 min in the islets of 1-year-old rats. The onset of glucose-induced second phase of insulin secretion, and the onset and peak of K+ depolarization- and arginine-induced insulin release were not delayed in the islets of 6-month and 1-year-old rats. Glucose-stimulated increase in cytosolic free calcium ([Ca2+]i) seemed not delayed in the islets of 1-year-old rats. We conclude that the first phase of glucose-induced insulin release by the islets is selectively delayed as rat ages. It was suggested that the defect lies distal to the elevation of [Ca2+]i.
Komatsu
M
M
Department of Geriatrics, Endocrinology and Metabolism, School of Medicine, Shinshu University, Japan.
Yokokawa
N
N
Nagasawa
Y
Y
Komiya
I
I
Aizawa
T
T
Takasu
N
N
Yamada
T
T
D000375:Aging / Q000378:metabolism*; D000818:Animals; D001120:Arginine / Q000494:pharmacology*; D002118:Calcium / Q000032:analysis; D046508:Culture Techniques; D003600:Cytosol / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D005947:Glucose / Q000008:administration & dosage / Q000494:pharmacology*; D007328:Insulin / Q000032:analysis / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000737:chemistry / Q000378:metabolism*; D008297:Male; D011188:Potassium / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D007328:Insulin; D001120:Arginine; D005947:Glucose; D011188:Potassium; D002118:Calcium