The effect of splanchnic block on renin production and renal haemodynamics in hypertensive patients.

In eighteen patients with hypertension the effect of a splanchnic block was studied with respect to the plasma renin activity (PRA) in the renal vein and to the renal haemodynamics. A significant reduction of the PRA was noted during splanchnic block, both in kidneys with arterial stenosis, and in those without. The decrease in renin activity took place despite a simultaneous decrease in renal vascular resistance, which in itself should increase the secretion of renin. This supports the view that the sympathetic nervous system dominates over the baroreceptors in patients with hypertension at the pressure levels investigated and if the sodium intake is restricted.