Effects of 5-hydroxytryptamine on rubidium ion fluxes and insulin release in cultured pancreatic islets.
We have incubated pancreatic islets isolated from noninbred ob/ob mice and NMRI mice for 3 days with or without 5-hydroxytryptamine (5-HT) in the medium and tested the effect of such long term treatment on subsequent insulin release and 86Rb+ accumulation and efflux. Two tenths millimolars of 5-HT abolished insulin release in response to 20 mM glucose. Two tenths millimolars of 5-HT also diminished the ability of islets to accumulate 86Rb+ and the effect of 10 mM glucose on 86Rb+ efflux. One one-hundredth millimolars of 5-HT had no effect on insulin release or 86Rb+ fluxes. Clearly, islets subjected to 5-HT for 3 days at concentrations that do not elicit demonstrable effects in short term incubations show a reduced secretory response. However, the physiological role of the high affinity uptake system for 5-HT in islet cells [Michaelis-Menten constant (Km) = 1.6 microM] remains unknown.
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002478:Cells, Cultured; D005260:Female; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D012413:Rubidium / Q000378:metabolism*; D012701:Serotonin / Q000494:pharmacology*
D007328:Insulin; D012701:Serotonin; D012413:Rubidium