Abstract
In the New Zealand strain of rats with genetic hypertension (GH) both plasma and renal renin levels have been shown by bioassay to be lower than in the parent strain of random bred normotensive (N) rats. In the present study plasma renin activity (PRA) was measured by radioimmunoassay for which the required volume of blood is much smaller and can be withdrawn rapidly. The results support the observation, made on renal renin levels, that renin levels in the GH rat are lower than in the N rat and are consistent with the view that the renin angiotensin system plays little role in the development or maintenance of hypertension in the GH rat.