title: Characteristics of ca influxes through voltage- and receptor-operated Ca channels in uterine smooth muscle.
abstract: The characteristics of Ca channels in isolated uterine smooth muscles from estradiol-treated ovariectomized rats were investigated. When the muscles were preincubated in Ca-depleted Ringer's solution for about 60 min and then immersed in Ca-depleted high K Ringer's solution or treated with acetylcholine (ACh) and serotonin (5-HT), no contractile response was observed. However, in both cases when CaCl2 was then added, a contractile response was induced. The contractile responses induced by KCl, ACh and 5-HT were inhibited dose-dependently by Ca antagonists and these inhibitions were counteracted competitively by an increase in the concentration of CaCl2. The characteristics of KCl-, ACh- and 5-HT-stimulated 45Ca uptake were investigated under the same conditions as the contractile responses. Results indicated that the contractile responses to high KCl, ACh and 5-HT induced by addition of CaCl2 in Ca-depleted Ringer's solution were dependent upon influx of Ca ions into uterine smooth muscle cells.
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002122:Calcium Chloride / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism*; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism*; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000494:pharmacology; D014599:Uterus / Q000187:drug effects / Q000378:metabolism*
chemical_list: D007473:Ion Channels; D012701:Serotonin; D004958:Estradiol; D011189:Potassium Chloride; D002122:Calcium Chloride; D000109:Acetylcholine; D002118:Calcium