Augmentation of somato-sympathetic reflex in the ischemic hindlimb of anesthetized rats

Activities of the visceral sympathetic nerve increase with noxious mechanic al stimulation. This study investigated the effects of noxious mechanical s timulation of hindlimb on arterial blood pressure, heart rate (HR) and rena l sympathetic nerve activities (RNA) in anesthetized rats intact or under i schemic conditions. This study utilized two methods of noxious mechanical s timulation. one was pinching of the hindpaw: the other, strangulation of th e ankle joint. Twenty-three male Wistar rats were used in the experiment. P inching and strangulation of the intact hindlimb caused an increase in RNA. The increased RNA was greater during strangulation than during pinch stimu lation (p < 0.0001). In the ischemic hindlimb produced by occlusion of the left common iliac artery, pinching and strangulation caused a further incre ase in RNA (p < 0.0001). Arterial blood pressure and HR significantly incre ased during strangulation with ischemic condition (p < 0.05). These results suggest that the reflex effects of somatosensory input on RNA were augment ed in the ischemic hindlimb. (C) 2000 Elsevier Science B.V. All rights rese rved.