5-HT2 receptor-stimulated calcium influx in ovine uterine artery in late pregnancy.
The effects of 5-hydroxytryptamine (5-HT) and 2,5-dimethoxy-4-methyl-amphetamine (DOM) on the Ca2+ influx in the ovine uterine artery in late pregnancy have been studied by measuring 45Ca2+ uptake. Both 5-HT and DOM (2.5 x 10(-8) M to 2.5 x 10(-5) M) induced concentration-dependent rises in 45Ca2+ uptake in the ovine uterine artery, from a basal level of 30.5 +/- 3.5 muMoles/kg wet tissue to peak levels of 91.1 +/- 9.2 and 84.2 +/- 8.1 muMoles/kg wet tissue, respectively. The Ca2+ influx evoked by 5-HT and DOM was inhibited by ketanserin in a concentration-dependent manner. Methiothepin (2.5 x 10(-7) M) also inhibited 5-HT-induced (2.5 x 10(-6) M) Ca2+ influx by 86%. No antagonism was found with 2.5 x 10(-6) M of 3-tropanyl-3,5-dichlorobenzoate (MDL 72222). The contraction elicited to 5-HT (10(-6) M) and DOM (10(-6) M) was blocked by D600 (10(-6) M) which also blocked the contraction produced to KCl (9 x 10(-2) M). Amrinone (10(-5) M) had no inhibitory effect on these contractions. In accord with the results of the contraction study, D600 (2.5 x 10(-6) M) blocked the Ca2+ influx stimulated by 5-HT (2.5 x 10(-6) M) and amrinone (2.5 x 10(-5) M) failed to inhibit 5-HT-induced Ca2+ influx. Nifedipine (2.5 x 10(-6) M) did not antagonize the influx of Ca2+ induced by 5-HT. Sodium nitroprusside inhibited the 5-HT-induced Ca2+ influx, indicating that at least part of its inhibitory effect on the vasoconstriction evolved by 5-HT is due to the inhibition of the influx of Ca2+.
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Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine, Iowa State University, Ames 50011.
Dyer
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D004290:DOM 2,5-Dimethoxy-4-Methylamphetamine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D000818:Animals; D001158:Arteries / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002132:Calcium Radioisotopes; D005260:Female; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000502:physiology*; D011985:Receptors, Serotonin / Q000187:drug effects / Q000502:physiology*; D012039:Regional Blood Flow / Q000187:drug effects; D012701:Serotonin / Q000494:pharmacology; D012702:Serotonin Antagonists / Q000494:pharmacology; D012756:Sheep; D014599:Uterus / Q000098:blood supply
D002121:Calcium Channel Blockers; D002132:Calcium Radioisotopes; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D004290:DOM 2,5-Dimethoxy-4-Methylamphetamine; D012701:Serotonin; D002118:Calcium