Effects of coronary artery occlusion on thoracic spinal neurons receiving viscerosomatic inputs.

Abstract

Action potentials of single cells in the gray matter of the T2 to T4 spinal segments of chloralose-anesthetized cats were recorded during occlusion of the anterior descending branch of the left coronary artery. Only cells responding both to visceral and somatic afferent inputs were examined. In 53% of the cells the discharge frequency was unaffected by coronary artery occlusion (CAO). The remaining 47% could be classified by four response patterns: 1) in 18% frequency increased immediately following the onset of CAO; 2) in 22%, frequency increased 13.6 +/- 3.3 (SE) s after CAO and the increased frequency usually was associated with changes in the configuration of the electrocardiogram; 3) in 3%, frequency increased at the onset of CAO and then increased more approximately 11 s later; 4) in 4%, inhibition of spontaneous activity occurred during CAO. A noxious pinch applied to the somatic receptive field maximally excited 94% and inhibited 6% of the cells. Since viscerosomatic convergence provides a basis for referred pain, these cells could potentially be involved with transmission of nociceptive information to regions of the brain that integrate pain sensations.