Contractile responses to angiotensin I and angiotensin II in hamster uterine smooth muscle.
Angiotensin I (A-I) and angiotensin II (A-II) produced dose-dependent increases in isometric tension in isolated strips of uterine smooth muscle prepared from ovariectomized golden hamsters treated with estrogen. Responses to A-II were consistent with receptor--occupancy theory of agonist--receptor interactions. Inhibition of angiotensin-converting enzyme virtually abolished responses to A-I but not those to A-II. Blockade of A-II receptors inhibited responses to both A-I and A-II. Cholinergic or alpha-adrenergic blockade did not alter uterine responses to either A-I or A-II. These findings suggest that contractile responses elicited in the isolated uterus of the hamster are due to its local conversion to A-II and subsequent interactions with specific A-II receptors. Such conversion occurs at least to the extent of 14 to 27 %.
D000804:Angiotensin II / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D006224:Cricetinae; D005260:Female; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D010646:Phentolamine / Q000494:pharmacology; D012504:Saralasin / Q000494:pharmacology; D013722:Teprotide / Q000494:pharmacology; D014599:Uterus / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology
D000804:Angiotensin II; D001285:Atropine; D013722:Teprotide; D012504:Saralasin; D010646:Phentolamine