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NEUROHUMORAL CONTROL OF CARDIOVASCULAR FUNCTION

Left vagal stimulation induces dynorphin release and suppresses substance P release from the rat thoracic spinal cord during cardiac ischemia

Departments of ¹Physiology and ²Pharmacology, College of Medicine, East Tennessee State University, Johnson City, Tennessee 37614

Submitted 15 April 2004 ; accepted in final form 2 August 2004

Electrostimulatory forms of therapy can reduce angina that arises from activation of cardiac nociceptive afferent fibers during transient ischemia. This study sought to determine the effects of electrical stimulation of left thoracic vagal afferents (C₈–T₁ level) on the release of putative nociceptive [substance P (SP)] and analgesic [dynorphin (Dyn)] peptides in the dorsal horn at the T₄ spinal level during coronary artery occlusion in urethane-anesthetized Sprague-Dawley rats. Release of Dyn and SP was measured by using antibody-coated microprobes. While Dyn and SP had a basal release, occlusion of the left anterior descending coronary artery only affected SP release, causing an increase from lamina I-VII. Left vagal stimulation increased Dyn release, inhibited basal SP release, and blunted the coronary artery occlusion-induced release of SP. Dyn release reflected activation of descending pathways in the thoracic spinal cord, because vagal afferent stimulation still increased the release of Dyn after bilateral dorsal rhizotomy of T₂–T₅. These results indicate that electrostimulatory therapy, using vagal afferent excitation, may induce analgesia, in part, via inhibition of the release of SP in the spinal cord, possibly through a Dyn-mediated neuronal interaction.

antibody-coated microprobes; angina; cardiac nervous system; analgesic peptides; nociceptive peptides

This article has been cited by other articles:

				X. Ding, J. L. Ardell, F. Hua, R. J. McAuley, K. Sutherly, J. J Daniel, and C. A. Williams Modulation of cardiac ischemia-sensitive afferent neuron signaling by preemptive C2 spinal cord stimulation: effect on substance P release from rat spinal cord Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2008; 294(1): R93 - R101. [Abstract] [Full Text] [PDF]