The influence of age on the distribution and activity of histamine receptors in the rat uterus.
In immature rat uterus histamine (10(-6) mol.l-1) potentiates by 25%, the carbachol (2 x 10(-6) mol.l-1) induced uterine contractions. This potentiation is abolished by mepyramine (6 x 10(-9) mol.l-1), an H1-receptor antagonist. Higher concentrations of histamine, up to 10(-4) mol.l-1, did not exert any inhibitory effect on carbachol-induced uterine contractions. In mature rat uterus carbachol-induced contractions are inhibited by histamine by about 25%. This inhibitory effect of histamine is significantly enhanced by mepyramine by about 50%. Inhibitory effects of higher concentrations of histamine, up to 10(-4) mol.l-1, are not enhanced by mepyramine. Cimetidine (4 x 10(-4) mol.l-1), an H2-receptor antagonist, abolished the inhibitory effects of histamine on carbachol-induced uterine contractions. In conclusion, in immature rat uterus there exists only H1 histamine receptors, activation of which exert an excitatory effect. In mature rat uterus there exists both H1 and H2 histamine receptors. The relaxant effect of histamine on mature rat uterus is exerted by activation of H2-receptors which predominate.
D000375:Aging; D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D002927:Cimetidine / Q000494:pharmacology; D004558:Electric Stimulation; D005260:Female; D006632:Histamine / Q000494:pharmacology; D011738:Pyrilamine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011968:Receptors, Histamine / Q000378:metabolism*; D011969:Receptors, Histamine H1 / Q000378:metabolism; D011970:Receptors, Histamine H2 / Q000378:metabolism; D014590:Uterine Contraction / Q000187:drug effects; D014599:Uterus / Q000378:metabolism*
D011968:Receptors, Histamine; D011969:Receptors, Histamine H1; D011970:Receptors, Histamine H2; D002927:Cimetidine; D006632:Histamine; D002217:Carbachol; D011738:Pyrilamine