Evidence for a role of microfilaments in insulin release from purified beta-cells.
To determine if the failure of purified beta-cells to secrete insulin in response to a glucose stimulus results from the absence of a cytoskeletal response, the effects of cytochalasins D and B on glucose-induced insulin release were investigated. Glucose alone failed to stimulate insulin release whereas glucose in the presence of glucagon, theophylline, cytochalasin D or B markedly potentiated insulin release. Cytochalasin D potentiated insulin secretion in a dose-dependent manner, and the combination of theophylline and cytochalasin D resulted in an insulin secretory response no greater than that produced by either agent alone. Both glucagon and theophylline are believed to mediate their effects via cAMP, however, cytochalasin D did not affect beta-cell cAMP levels. These results suggest that the inability of purified beta-cells to release insulin may result from the absence of the necessary modulation of the state of the microfilaments.
Wang
J L
JL
Department of Pathology, Washington University School of Medicine, St. Louis, Missouri 63110.
Easom
R A
RA
Hughes
J H
JH
McDaniel
M L
ML
D008841:Actin Cytoskeleton / Q000502:physiology*; D000818:Animals; D000242:Cyclic AMP / Q000502:physiology; D003571:Cytochalasin B / Q000494:pharmacology*; D015638:Cytochalasin D / Q000494:pharmacology*; D003599:Cytoskeleton / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D005934:Glucagon / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000378:metabolism*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012636:Secretory Rate / Q000187:drug effects; D013806:Theophylline / Q000494:pharmacology
D007328:Insulin; D015638:Cytochalasin D; D003571:Cytochalasin B; D005934:Glucagon; D013806:Theophylline; D000242:Cyclic AMP; D005947:Glucose