Comparison of the somatosympathetic reflex in normotensive and spontaneously hypertensive rats.

Acute experiments under chloralose anaesthesia were performed in normotensive (Wistar and Wistar-Kyoto) and hypertensive (SHR) rats for recording of electrical discharge in the upper cervical sympathetic stem in response to stimulation of afferent fibers of the median nerve of the forelimb. These experiments showed that the evoked response was of the same shape in hypertensive rats as in normotensive rats. The latent period, duration of each discharge, and spectral characteristics of the somatosympathetic reflex were identical in animals of all the lines studied, though the amplitude of the reflex was greater in SHR rats than in normotensive animals. It is suggested that the organization of the somatosympathetic reflex is identical in hypertensive and normotensive rats. The reflex excitability of the sympathetic nervous system was increased in SHR rats.