Suppression of sympathetic nervous function in low-renin essential hypertension.

Study of general haemodynamics in 15 patients with low-renin essential hypertension showed haemodynamic and pathophysiological heterogeneity. However, there was suppression of sympathetic nervous system function in all low-renin patients, regardless of haemodynamic pattern. Subnormal sympathetic nervous activity was manifested by a low normal mean plasma-noradrenaline concentration at rest, diminished noradrenaline responsiveness to postural stimulation, and a reduced blood-pressure response to the indirectly acting sympathomimetic amine tyramine. It is proposed that the syndrome of low-renin essential hypertension is of diverse aetiology, but with secondary sympathetic nervous system underactivity as a feature common to the various forms. The low plasma-renin activity is probably an expression of defective sympathetic nervous system stimulation of renin release.