Journal of Neurophysiology, Vol 51, Issue 4 636-648, Copyright © 1984 by APS

ARTICLES

Responses of thoracic spinothalamic and spinoreticular cells to coronary artery occlusion

R. W. Blair, W. S. Ammons and R. D. Foreman

Spinothalamic and spinoreticular neurons in the C8-T5 spinal segments were examined for responsiveness to occlusion of the left main, left circumflex (CX), or left anterior descending (LAD) coronary artery in monkeys and cats. Four types of cell response to occlusion were observed, as follows: 1) cell activity increased (6 responses) or decreased (1 response) to myocardial ischemia produced by the occlusion; 2) cell activity increased at the onset of occlusion, adapted, and then increased again as ischemia developed (6 responses); 3) cell activity increased at the onset or release of occlusion, and rapidly adapted (13 responses) or remained elevated throughout the occlusion (2 responses); and 4) no response to occlusion (14 tests). Among the types of responses to occlusion, both the magnitude of increased cell activity as well as the spontaneous discharge rates were similar. There were no differences in types of response according to coronary artery ligated. Fourteen cells were tested for responses to separate occlusions of the LAD and CX. Ten cells responded differently to the two occlusions, and four cells exhibited similar responses. C-fiber input onto a neuron was significantly related to whether a cell exhibited a response to cardiac ischemia. Since every cell with C-fiber input did not respond to ischemia, however, this input was not sufficient to predict whether a cell would respond to ischemia. All cells had somatic fields, and all cells responded to noxious stimulation of the somatic field. Some cells also received input from hair movement. The modality of the effective somatic stimulus was not related to type of response to coronary artery occlusion. Spinothalamic and spinoreticular neurons responded similarly to occlusion. Type of response was neither related to cell location in spinal cord nor to projection site in brain. We conclude that spinothalamic and spinoreticular neurons respond to coronary artery occlusion. Different neurons may receive input from different regions of the heart as well as from different types of visceral afferents, resulting in various responses to occlusion. The population of cells excited from ischemia of a given portion of myocardium may determine how the brain interprets the noxious information and refers pain to different somatic structures.

This article has been cited by other articles:

				P. A. Gwirtz, J. Dickey, D. Vick, M. A. Williams, and B. Foresman Viscerosomatic interaction induced by myocardial ischemia in conscious dogs J Appl Physiol, August 1, 2007; 103(2): 511 - 517. [Abstract] [Full Text] [PDF]

				A. M. Degtyarenko and M. P. Kaufman Spinoreticular neurons that receive group III input are inhibited by MLR stimulation J Appl Physiol, July 1, 2002; 93(1): 92 - 98. [Abstract] [Full Text] [PDF]

				M. J. Chandler, J. Zhang, C. Qin, Y. Yuan, and R. D. Foreman Intrapericardiac injections of algogenic chemicals excite primate C1-C2 spinothalamic tract neurons Am J Physiol Regulatory Integrative Comp Physiol, August 1, 2000; 279(2): R560 - R568. [Abstract] [Full Text] [PDF]

				E. D. Al-Chaer, Y. Feng, and W. D. Willis Comparative Study of Viscerosomatic Input Onto Postsynaptic Dorsal Column and Spinothalamic Tract Neurons in the Primate J Neurophysiol, October 1, 1999; 82(4): 1876 - 1882. [Abstract] [Full Text] [PDF]

				M. J. Chandler, J. Zhang, and R. D. Foreman Cardiopulmonary Sympathetic Input Excites Primate Cuneothalamic Neurons: Comparison With Spinothalamic Tract Neurons J Neurophysiol, August 1, 1998; 80(2): 628 - 637. [Abstract] [Full Text] [PDF]