Abstract
It has been proven that noxious articular stimulation of hindlimb produce reflex increase in heart rate, in anesthetized animals, to be a reflex response whose reflex center is in the brain and efferent arc is a cardiac sympathetic nerve. Using central nervous system (CNS)-intact and acutely spinalized anesthetized rats, the present study aimed to examine the possibility of whether articular stimulation could influence heart rate via sympathetic nerve at the spinal level. In CNS-intact rats, noxious articular movement of both knee and elbow joint produced an increase in the cardiac sympathetic nerve activity and heart rate. In acutely spinalized rats, noxious movement of elbow joint produced large increases in the cardiac sympathetic nerve activity and heart rate, while noxious movement of knee joint induced no increase in the cardiac sympathetic nerve activity and only a marginal increase in heart rate. As the marginal heart rate response following knee joint stimulation in spinalized rats was abolished after adrenalectomy, the responses were suggested to be induced by catecholamine secreted from the adrenal grand. It is concluded that the spinal cord is capable of producing propriospinally the reflex increases in heart rate via reflex activation of the cardiac sympathetic efferent nerve following stimulation to the elbow joint stimulation whose afferent information enters the spinal cord at the same segments or segments overlapping the cardiac sympathetic outflow. [J Physiol Sci. 2006;56 Suppl:S135]
