Effect of nicardipine on human placental vasculature.
The effect of nicardipine on segments of human chorionic arteries and veins was studied. Nicardipine induced the concentration-dependent inhibition of K+ (75 mM) contractions in both kinds of vessels. Preincubation of these vessels with nicardipine (10(-5) M, which produced maximal reduction of K+ responses) caused a greater decrease of contractions induced by K+ (75 mM) than of those induced by serotonin (10(-6) M). Ca suppression from the medium reduced the responses elicited by serotonin and practically abolished those induced by K+. The subsequent Ca addition induced contractions which were diminished by nicardipine (10(-5) M) in both types of vessels. Nicardipine also attenuated serotonin contractions in Ca-free medium, especially in veins. Both serotonin (10(-6) M) and K+ (75 mM) increased 45Ca uptake. This effect was decreased by nicardipine (10(-5) M), mainly in veins. Basal 45Ca uptake was unaffected by this Ca antagonist. These findings indicate that human chorionic vessels are sensitive to nicardipine; the responses mediated by Ca entry through voltage-dependent Ca channels are inhibited to a greater extent by this Ca antagonist than those mediated by receptor-dependent Ca channels.
Marín
J
J
Departamento de Farmacología y Terapéutica, Facultad de Medicina, Universidad de Extremadura, Madrid, Spain.
Reviriego
J
J
D001158:Arteries / Q000187:drug effects; D002132:Calcium Radioisotopes; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism; D009529:Nicardipine / Q000494:pharmacology*; D010920:Placenta / Q000098:blood supply*; D011188:Potassium / Q000494:pharmacology; D011247:Pregnancy; D012039:Regional Blood Flow / Q000187:drug effects; D012701:Serotonin / Q000494:pharmacology; D014680:Veins / Q000187:drug effects
D002132:Calcium Radioisotopes; D012701:Serotonin; D009529:Nicardipine; D011188:Potassium