Pharmacological characterization of histamine receptors in the rabbit renal artery.
Histamine receptors were characterized pharmacologically in the rabbit renal artery. Histamine concentration-dependent contractions were blocked by chlorpheniramine (pA2 = 8.25 +/- 0.16) and mepyramine (pA2 = 9.80 +/- 0.22). A low concentration of metiamide (0.5 microM) enhanced significantly the effect of histamine. Higher concentrations either had no effect or reduced the contractile response to histamine. Impromidine, dimaprit and, in the presence of chlorpheniramine or mepyramine, histamine (at the concentrations that produced contractions) relaxed the precontracted vessel. The relaxant effect of histamine was quantitatively greater in the presence of mepyramine than it was in the presence of chlorpheniramine. Endothelial removal did not influence the contractile response to histamine but enhanced the relaxation suggesting the presence of histamine receptors mediating contraction in the intima. Relaxation responses to histamine and dimaprit were blocked competitively by cimetidine (pA2 = 6.65 +/- 0.10 and 6.60 +/- 0.05 respectively). It is concluded that there are two types of histamine receptors in the renal artery of the rabbit; H1-receptor mediating contraction and H2-receptor mediating relaxation. Both types of receptors are present in the media: some excitatory receptors may be present in the intima.
D000818:Animals; D004727:Endothelium / Q000502:physiology; D006632:Histamine / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D008785:Metiamide / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D011738:Pyrilamine / Q000494:pharmacology; D011817:Rabbits; D011968:Receptors, Histamine / Q000187:drug effects*; D011969:Receptors, Histamine H1 / Q000187:drug effects; D011970:Receptors, Histamine H2 / Q000187:drug effects; D012077:Renal Artery / Q000187:drug effects*
D011968:Receptors, Histamine; D011969:Receptors, Histamine H1; D011970:Receptors, Histamine H2; D008785:Metiamide; D006632:Histamine; D011738:Pyrilamine