Evidence for multiple sources of calcium involved on the contractile effects of agonists in the dog uterus. Influence of ovarian sexual hormones.
We compared the characteristics of Ca2+ pools involved in the contractile effect of acetylcholine (Ach), histamine (Hist), oxytocin (Oxy) and barium (Ba2+) in prepuberal untreated or estrogen plus progesterone dominated uteri. After Ca2+ (0.2 mM) withdrawal different rates of decay for cited agonists were observed. If Ca2+ concentration was increased to 2.0 mM before the Ca2+ withdrawal, the t 1/2 for Ach and Hist were markedly increased. Hormonal treatment significantly increase the rate of decay for all agonists except for Ba2+ independent of the initial Ca2+ concentration, suggesting that in this condition the tightly bound Ca2+ is absent.
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001464:Barium / Q000494:pharmacology; D017609:Barium Compounds; D002118:Calcium / Q000378:metabolism*; D002712:Chlorides; D004285:Dogs; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D006632:Histamine / Q000494:pharmacology; D066298:In Vitro Techniques; D007700:Kinetics; D010121:Oxytocin / Q000494:pharmacology; D011374:Progesterone / Q000494:pharmacology; D013997:Time Factors; D014590:Uterine Contraction / Q000187:drug effects*; D014599:Uterus / Q000378:metabolism*
D017609:Barium Compounds; D002712:Chlorides; C024986:barium chloride; D001464:Barium; D011374:Progesterone; D004958:Estradiol; D010121:Oxytocin; D006632:Histamine; D000109:Acetylcholine; D002118:Calcium