The Effects of Utricular Lesions on Sympathetic Controlo of Cardiovascular Function During +GZ Stress

Abstract : The vestibular system has long been recognized to play an important role in autonomic control, having important influences over the gastrointestinal, cardiovascular, renal, respiratory, and oculomotor systems. The effects of vestibular stimulation and lesion have been observed in these systems. A recent theory sought to clarify the previously documented vestibular-autonomic relationships by postulating the utricles to have a predominantly sympatho-excitatory autonomic effect whereas the other vestibular end-organ systems exert a predominantly parasympatho-excitatory/sympatho-inhibitory effect. Thus this proposed research attempted to eliminate untricular sympathetic inputs by selectively destroying hair cells of the otolith organs ( of the utricles in particular) in animals by exposing them to extremely high and prolonged Gy stimulation (+, - or both). The specific measure of sympathetic function was to be changes in G- induced loss of consciousness ( 0-LOC) induction time and cardiac output during +Oz stress. A utricular hair cell lesion model prolonged centrifugation of rats in the Gy axis was developed. The method of eliminating vestibular influence offers advantage of being fairly" non- invasive