Cardiorespiratory effects evoked by electrical stimulation of somatic afferent fibers.

Several neurophysiological studies have shown that electrical activation of afferent fibers of somatic nerves can evoke inhibitory or excitatory cardiovascular responses. The present investigation was undertaken to examine the effects induced by electrical stimulation of somatic nerves on cardiocirculatory and respiratory functions in anesthetized rabbits. Both low frequency stimulation and high frequency stimulation of afferent fibers of somatic nerves caused two distinct patterns of cardiocirculatory and respiratory reflex responses absolutely similar to those observed in our previous experiments on rabbits with dynamic and static exercise. The present findings do not support the existence in the somatic nerves of afferent fibers with cardiorespiratory effect having physiological functions different from that of producing cardiopulmonary adjustments to muscular activity.