Jpn. J. Pharmacol. 84 (4), 367-373 (2000)

-Current Perspective-
Actions of Tachykinins Within the Heart and Their Relevance to Cardiovascular Disease

Donald B. Hoover*, Yingzi Chang, John C. Hancock and Lili Zhang

Department of Pharmacology, James H. Quillen College of Medicine, East Tennessee State University, P.O. Box 70577, Johnson City, TN 37614, USA
*Corresponding author:ü@FAX:+1-423-439-8773

Abstract: Substance╩P and neurokinin╩A are tachykinins that are co-localized with calcitonin gene-related peptide (CGRP) in a unique subpopulation of cardiac afferent nerve fibers. These neurons are activated by nociceptive stimuli and exhibit both sensory and motor functions that are mediated by the tachykinins and/or CGRP. Sensory signals (e.g., cardiac pain) are transmitted by peptides released at central processes of these neurons, whereas motor functions are produced by the same peptides released from peripheral nerve processes. This review summarizes our current understanding of intracardiac actions of the tachykinins. The major targets for the tachykinins within the heart are the intrinsic cardiac ganglia and coronary arteries. Intrinsic cardiac ganglia contain cholinergic neurons that innervate the heart and coronary vasculature. Tachykinins can stimulate NK3 receptors on these neurons to increase their excitability and evoke spontaneous firing of action potentials. This action provides a mechanism whereby tachykinins can indirectly influence cardiac function and coronary tone. Tachykinins also have direct effects on coronary arteries to decrease or increase tone. Stimulation of NK1 receptors on the endothelium causes vasodilation mediated by nitric oxide. This effect is normally dominant, but NK2 receptor-mediated vasoconstriction can also occur and is augmented when NK1 receptors are blocked. It is proposed that these ganglion stimulant and vascular actions are manifest by endogenous tachykinins during myocardial ischemia.

Keywords: Tachykinin, Cholinergic neuron, Coronary artery, Cardiac afferent, Myocardial ischemia

Copyrightę The Japanese Pharmacological Society 2000

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