title: Measurement of cytosolic free calcium concentration in relation to insulin release in normal rat pancreatic islets.
abstract: The effects of glucose (16.7 mM), potassium (50 mM), forskolin (20 microM), dibutyryl cyclic AMP (1 mM) and arachidonic acid (82 microM) upon insulin release and cytosolic free calcium concentrations ([Ca2+]i) were investigated in normal rat pancreatic islets. Potassium, forskolin and dibutyryl cyclic AMP significantly raised [Ca2+]i, but elicited only minimal insulin release. In the absence of extracellular Ca2+, glucose evoked insulin release, but failed to augment [Ca2+]i. Arachidonic acid increased [Ca2+]i both in Ca-depleted and -repleted medium, but promoted insulin release only in Ca2+-repleted environment. These new observations clearly demonstrate by direct measurements that although [Ca2+]i is an important factor in exocytotic insulin release, its effect is subject to amplification or antagonism.
authors.affiliation: Research Service, Veterans Administration Medical Center, Denver, CO 80220.
authors.forename: B
authors.initials: B
authors.lastname: Draznin
authors.forename: S A
authors.initials: SA
authors.lastname: Metz
authors.forename: K E
authors.initials: KE
authors.lastname: Sussman
authors.forename: J W
authors.initials: JW
authors.lastname: Leitner
mesh_terms: D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000502:physiology; D001786:Blood Glucose / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D000242:Cyclic AMP / Q000502:physiology; D003600:Cytosol / Q000378:metabolism*; D005089:Exocytosis; D007328:Insulin / Q000378:metabolism*; D007515:Islets of Langerhans / Q000378:metabolism; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D001095:Arachidonic Acids; D001786:Blood Glucose; D007328:Insulin; D016718:Arachidonic Acid; D000242:Cyclic AMP; D002118:Calcium