Interaction of bradykinin and des-Arg9-bradykinin with isolated pig coronary arteries: mechanical and electrophysiological events.
This paper describes the effect of bradykinin (BK) and des-Arg9-BK on the isometric tension and smooth muscle membrane potential of transverse strips of pig coronary artery. BK causes a relaxation of contracted muscle. This effect is particularly evident in muscle which has previously been contracted by acetylcholine. The relaxation is accompanied by a transient hyperpolarization of the vascular smooth muscle. Des-Arg9-BK, in contrast, causes a contraction of the muscle which is not accompanied by a significant change of transmembrane potential. The relaxing action of BK depends on the presence of the endothelium. In a "cascade" experiment, evidence is presented that a relaxing factor is released by the endothelium in response to BK. Thus the perfusate from a BK-stimulated intact artery can cause the relaxation of a pre-contracted de-endothelialized artery. We conclude that the endothelium has B2-receptors which cause the release of a humoral factor which hyperpolarizes and relaxes the muscle. The contracting action of des-Arg9-BK does not depend on the endothelium and appears to be mediated through B1-receptors directly on smooth muscle by pharmacomechanical coupling.
D000818:Animals; D001920:Bradykinin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D003331:Coronary Vessels / Q000187:drug effects*; D004727:Endothelium / Q000502:physiology; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D018002:Receptors, Bradykinin; D018040:Receptors, Neurokinin-1; D017981:Receptors, Neurotransmitter / Q000502:physiology*; D013373:Substance P / Q000502:physiology; D013552:Swine
D018002:Receptors, Bradykinin; D018040:Receptors, Neurokinin-1; D017981:Receptors, Neurotransmitter; C024626:bradykinin, des-Arg(9)-; D013373:Substance P; D001920:Bradykinin