Myocardial ischemia induces the release of substance P from cardiac afferent neurons in rat thoracic spinal cord

• Published in: American journal of physiology. Heart and circulatory physiology Vol. 286; no. 5; pp. H1654 - H1664
• Main Authors: Hua, Fang, Ricketts, Brian A, Reifsteck, Angela, Ardell, Jeffrey L, Williams, Carole A
• Format: Journal Article
• Language: English
• Published: United States 01.05.2004
• Subjects: Animals; Coronary Disease - physiopathology; Exudates and Transudates - metabolism; Female; Heart - innervation; Male; Myocardial Ischemia - metabolism; Myocardial Ischemia - physiopathology; Neurons, Afferent - metabolism; Nociceptors - physiopathology; Rats; Rats, Sprague-Dawley; Spinal Cord - metabolism; Substance P - metabolism; Thoracic Vertebrae
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.00906.2003

Departments of 1 Physiology and 2 Pharmacology, Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee 37614 Submitted 22 September 2003 ; accepted in final form 10 December 2003 Antibody-coated microprobes were inserted into the thoracic (T3–4) spinal cord in urethane-anesthetized Sprague-Dawley rats to detect the differences in the release of immunoreactive substance P-like (irSP) substances in response to differential activation of cardiac nociceptive sensory neurons (CNAN). CNAN were stimulated either by intrapericardial infusion of an inflammatory ischemic exudate solution (IES) containing algogenic substances (i.e., 10 mM each of adenosine, bradykinin, prostaglandin E 2 , and 5-hydroxytryptamine), or by transient occlusion of the left anterior descending coronary artery (CoAO). There was widespread basal release of irSP from the thoracic spinal cord. Stimulation of the CNAN by IES did not alter the pattern of release of irSP. Conversely, CoAO augmented the release of irSP from T3–4 spinal segments from laminae I–VII. This CoAO-induced irSP release was eliminated after thoracic dorsal rhizotomy. These results indicate that heterogeneous activation of cardiac afferents, as with focal coronary artery occlusion, represents an optimum input for activation of the cardiac neuronal hierarchy and for the resultant perception of angina. Excessive stimulation of cardiac nociceptive afferent neurons elicited during regional coronary artery occlusion involves the release of SP in the thoracic spinal cord and suggests that local spinal cord release of SP may be involved in the neural signaling of angina. antibody-coated microprobes; coronary artery occlusion; algogenic substances; angina; cardiac nervous system Address for reprint requests and other correspondence: C. A. Williams, Dept. Physiology, Quillen College of Medicine, East Tennessee State Univ., Stanton-Gerber Hall, B-137, PO Box 70576, Johnson City, TN 37614-1708 (E-mail: williams{at}mail.etsu.edu ).