Relationship between histamine-induced changes of cyclic AMP and mechanical activity on smooth muscle preparations of the guinea-pig ileum and the rabbit mesenteric artery.
On guinea-pig ileum and rabbit mesenteric artery contracted by high potassium (100 mM) histamine produced relaxations which were inhibited by the H2-receptor antagonist metiamide. These results are thus indicative for the role of H2-receptors in mediating relaxation and for H1-receptors in mediating contraction on smooth muscle. Time course studies for the relaxing and cyclic AMP responses to histamine showed that the cyclic AMP increase preceded the H2-receptor mediated relaxation. The cyclic AMP increase in response to histamine was prevented by metiamide, but remained unaffected by mepyramine on both the guinea-pig ileum and the rabbit mesenteric artery. In addition, dose-response curves obtained on the mesenteric artery demonstrated that the H2-receptor mediated depressor responses coincided with cyclic AMP increases. Thus, these results gave clear-cut evidence that cyclic AMP is an intracellular metabolic event only implicit in the H2-receptor mediated relaxation, but not in the H1-receptor mediated contraction on smooth muscle preparations.
D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism*; D005260:Female; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology*; D007082:Ileum / Q000187:drug effects / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects / Q000378:metabolism; D008785:Metiamide / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism; D011738:Pyrilamine / Q000494:pharmacology; D011817:Rabbits; D013997:Time Factors
D008785:Metiamide; D006632:Histamine; D000242:Cyclic AMP; D011738:Pyrilamine