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

Activities of the visceral sympathetic nerve increase with noxious mechanical stimulation. This study investigated the effects of noxious mechanical stimulation of hindlimb on arterial blood pressure, heart rate (HR) and renal sympathetic nerve activities (RNA) in anesthetized rats intact or under ischemic conditions. This study utilized two methods of noxious mechanical stimulation. One was pinching of the hindpaw; the other, strangulation of the ankle joint. Twenty-three male Wistar rats were used in the experiment. Pinching and strangulation of the intact hindlimb caused an increase in RNA. The increased RNA was greater during strangulation than during pinch stimulation (p < 0.0001). In the ischemic hindlimb produced by occlusion of the left common iliac artery, pinching and strangulation caused a further increase in RNA (p < 0.0001). Arterial blood pressure and HR significantly increased during strangulation with ischemic condition (p < 0.05). These results suggest that the reflex effects of somatosensory input on RNA were augmented in the ischemic hindlimb.