Responses of arterial smooth muscle from normotensive and pre-eclamptic subjects to the calcium channel agonist, Bay K 8644.
The effect of Bay K 8644, a dihydropyridine Ca2+ agonist, on in vitro contractile responses of inferior epigastric arteries from normotensive (N) and pre-eclamptic (P) subjects has been investigated, with a view to further defining the mechanism of the increased vascular sensitivity associated with pregnancy-induced hypertension. Bay K 8644 (10(-10)-10(-7) M) caused dose-dependent contractions of N as well as P arteries under resting conditions in the order: P greater than N and caused development of rhythmic contractions in both N and P arteries. Bay K 8644 effects were prevented by 3 X 10(-8) M Nifedipine (a Ca+2 antagonist). Bay K 8644 also significantly (P less than 0.05) enhanced the sensitivity as well as maximal contractile responses to CaCl2 in 40 mM K+-depolarized Ca-depleted N and P arteries in the order: P greater than N. The results suggest that the increased peripheral vascular sensitivity associated with pregnancy-induced hypertension may be due, at least in part, to enhanced activity of the potential-sensitive Ca2+ channels in arterial smooth muscle plasmalemma.
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000503:physiopathology; D011225:Pre-Eclampsia / Q000503:physiopathology*; D011247:Pregnancy; D014655:Vascular Resistance / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects
D007473:Ion Channels; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D002118:Calcium