Effect of calcium withdrawal and agents affecting calcium translocation on agonist-induced contractions of the rabbit ovarian artery.
The effect of extracellular calcium ion (Ca2+) depletion, diltiazem, D-600 and TMB-8 on potassium (K+), norepinephrine-(NE) and histamine-induced contractions of the rabbit isolated ovarian artery was studied. K+-induced contractions, which were biphasic, were rapidly lost (congruent to 5 min) when calcium was removed from the physiological saline solution (O-Ca2+ PSS). NE and histamine-induced contractions also declined rapidly under nominal O-Ca2+ conditions without any evidence of a depletion resistant component. However, after 1 h under these conditions there was a partial restoration of their responses. EGTA (10(-3) mol/l) abolished these contractions to NE and histamine but not those in normal PSS. Diltiazem and D-600 were more effective against K+-induced than NE- and histamine-induced contractions while the intracellular Ca2+ antagonist TMB-8 was equally effective against all three responses. Histamine could still evoke contraction of the K+-contracted ovarian artery after this had been completely abolished with diltiazem or D-600 but not TMB-8. These results are interpreted to suggest that K+, NE and histamine probably release intracellular Ca2+ to evoke contractions of the ovarian artery. They differ, however, in the mechanisms they employ to facilitate entry of extracellular calcium, which in turn leads to intracellular calcium release.
D000818:Animals; D001158:Arteries / Q000502:physiology*; D002118:Calcium / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004110:Diltiazem / Q000494:pharmacology; D004347:Drug Interactions; D005260:Female; D005707:Gallic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D005711:Gallopamil / Q000494:pharmacology; D006632:Histamine / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology; D009638:Norepinephrine / Q000494:pharmacology*; D010053:Ovary / Q000098:blood supply; D011188:Potassium / Q000378:metabolism; D011817:Rabbits
D005711:Gallopamil; C006014:8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate; D005707:Gallic Acid; D006632:Histamine; D004110:Diltiazem; D011188:Potassium; D002118:Calcium; D009638:Norepinephrine