Regulation of intracellular Ca2+ by 8-bromoguanosine 3':5'-cyclic monophosphate, felodipine and ryanodine in rat caudal artery.
45Ca2+ efflux in isolated rat caudal artery was measured in the absence and presence of 8-bromoguanosine 3':5'-cyclic monophosphate (8-Br-cGMP), felodipine or ryanodine after stimulation of alpha 1-adrenoceptors. The objectives of this study were to identify the mechanisms of action of 8-Br-cGMP, felodipine and ryanodine in a vascular resistance vessel. 8-Br-cGMP and ryanodine but not felodipine increased basal 45Ca2+ efflux. Phenylephrine-induced 45Ca2+ efflux was reduced by all three antagonists. The results of this study demonstrate that, (1) 8-Br-cGMP-mediated relaxation is affected in part by an increased extrusion of intracellular Ca2+ and/or inhibition of intracellular Ca2+ release, (2) the Ca(2+)-channel antagonist, felodipine, impairs intracellular Ca2+ release and (3) ryanodine reduced phenylephrine-induced Ca2+ efflux by depleting intracellular Ca2+ stores.
Lum Min
S A
SA
Department of Pharmacology and Therapeutics, Faculty of Medicine, University of British Columbia, Vancouver, Canada.
Tabrizchi
R
R
D000818:Animals; D001158:Arteries / Q000187:drug effects* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002132:Calcium Radioisotopes; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000494:pharmacology; D015736:Felodipine / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012433:Ryanodine / Q000494:pharmacology*
D002121:Calcium Channel Blockers; D002132:Calcium Radioisotopes; D012433:Ryanodine; C016276:8-bromocyclic GMP; D006152:Cyclic GMP; D015736:Felodipine; D002118:Calcium