Effect of Ca2+ agonist Bay K 8644 in human placental arteries.
1. Bay K 8644 (0.1 microM induced weak contractions in human placental artery segments that were increased in the presence of 7.5 mM K+. K+ and serotonin (5-HT) induced contractions that were enhanced by preincubation of segments with Bay K 8644. These enhancements were reduced by nifedipine (0.1 microM) and diltiazem (1 microM). 2. Bay K 8644 induced a 45Ca2+ uptake increase which was potentiated by depolarization with K+ (less than 30 mM) and antagonized by nifedipine. K+ (15 and 30 mM) and 5-HT (1 microM) induced 45Ca2+ uptake that was enhanced by Bay K 8644. 3. These results suggest that Bay K 8644: (1) is unable to activate the quiescent potential-operated Ca2+ channels (POCs) of these arteries, and (2) activates receptor (5-HT)-operated Ca2+ channels or facilitates Ca2+ influx through POCs activated by 5-HT.
Barrús
M T
MT
Departamento de Fisiología, Facultad de Medicina, Universidad Autónoma, Madrid, Spain.
Reviriego
J
J
Marín
J
J
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology*; D001158:Arteries / Q000187:drug effects / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002120:Calcium Channel Agonists / Q000494:pharmacology*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002132:Calcium Radioisotopes; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007537:Isometric Contraction / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism; D010920:Placenta / Q000098:blood supply* / Q000187:drug effects / Q000378:metabolism; D011188:Potassium / Q000494:pharmacology; D011247:Pregnancy; D012039:Regional Blood Flow / Q000187:drug effects; D012701:Serotonin / Q000378:metabolism
D002120:Calcium Channel Agonists; D002121:Calcium Channel Blockers; D002132:Calcium Radioisotopes; D012701:Serotonin; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D011188:Potassium; D002118:Calcium