Relation of plasma renin to blood pressure in a patient with coarctation.

Among several factors determining secretion of renin is mean arterial pressure (Skinner, McCubbin, and Page, 1964). Plasma renin is, in some instances, increased in renal artery stenosis (Helmer, 1964; Brown et al., 1964; Veyrat et al., 1964): and it is probable that this increase is due to lowered arterial pressure beyond the obstruction. In coarctation of the aorta there is a similar discrepancy between the pressure at which arterial blood is supplied to the kidney and that at which it is supplied to the upper part of the body. It is rather difficult to measure the pressure beyond a renal artery stenosis, but fairly simple to< measure that distal to a coarctation. It seemed likely that in coarctation (and in renal artery stenosis) the control of renin secretion would be normal but appropriate to arterial pressure in the kidney rather than to brachial arterial pressure. Observations of plasma renin, brachial, and femoral arterial pressure were made in a patient with coarctation before and after surgical repair: measurements were also made before and after intravenous infusion of sodium nitroprusside (Page et al., 1955), in order that plasma renin levels might be compared at various arterial pressures.