Effect of histamine treatment on dopamine tachyphylaxis of canine tracheal smooth muscle.
In order to understand how histamine-sensitized airways may react to exogenous dopamine, we investigated the effect of histamine treatment on the dopamine-induced contractions of canine tracheal smooth muscle. The results showed that preconstricting muscle strips with histamine (10(-6) M to 10(-4) M) not only increased the amplitude of dopamine-induced contraction, but also lowered the concentration of dopamine required to provoke contraction from 10(-4) M to 10(-6) M. In muscle strips desensitized by repeated challenges of 10(-3) M dopamine, a 15-min treatment with 10(-4) M histamine transiently restored the response. The restored contractions were decreased by the dopaminergic antagonist, domperidone, and the alpha 2-adrenoceptor antagonist, yohimbine, and increased by the beta 1-adrenoceptor antagonist, atenolol. It is concluded that in addition to its role in mediating airway constriction, histamine can promote and enhance the contractile response of canine tracheal smooth muscle to dopamine. Histamine treatment restored the dopamine response of desensitized tracheal muscle with resensitization of the adrenoceptors.
Chen
C J
CJ
Department of Physiology, National Yang-Ming Medical College, Taipei, Taiwan, ROC.
Shue
C H
CH
D000818:Animals; D004285:Dogs; D004298:Dopamine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006632:Histamine / Q000494:pharmacology*; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D014132:Trachea / Q000187:drug effects*
D006632:Histamine; D004298:Dopamine