Sympathetic nervous activity in renal and DOC hypertensive rats

The sympathetic tone of the splanchnic nerve was quantified in renal and deoxycorticosterone (DOC) hypertensive rats under pentobarbital anesthesia by measuring equivalent stimulation frequency (ESF). ESF is the frequency of stimulus to the peripheral cut end of the nerve required to restore the preseverance level of arterial pressure. It is assumed to represent the average discharge rate of the nerve before severance. ESF was markedly increased in DOC hypertension 2 weeks after initiation of the DOC-salt treatment. It was relatively decreased after 10 weeks, but was still higher than in the controls. In renal hypertension (clipping of the left renal artery), ESF was decreased considerably 2 weeks and slightly 10 weeks after clipping. When the contralateral kidney had been removed simultaneously with clipping (clip plus uninephrectomy, ESF was not significantly changed. It is suggested that the sympathetic nervous system participates greatly in the pathogenesis of DOC hypertension but not of renal hypertension.