Lyon genetically hypertensive rats: an animal model of "low renin hypertension".

This paper reviews the data which demonstrate that Lyon genetically hypertensive (LH) rats exhibit a low renin form of hypertension. Since when compared to normotensive controls, LH rats exhibit a low renin release and are salt-sensitive. Despite this, the blockade of the renin-angiotensin system normalizes the blood pressure level and the regional blood flows in LH rats. Such a discrepancy between the compulsory presence of angiotensin II for the hypertension to develop and the low level of renin release seen in LH rats led to two hypotheses: 1) the existence of an early, short lasting increase of renin release which would be sufficient for the occurrence of a stable hypertension; 2) an hypersensitivity to the effects of angiotensin II. The study of the long-term effects of early short lasting blockades of the renin-angiotensin system allowed to exclude the first hypothesis. Concerning a hypersensitivity to the effects of angiotensin II, it was found to exist in the preglomerular vessels of LH rats. This increased response of renal vessels to angiotensin II may well explain the low renin form of hypertension of our model and therefore represents an important field for further research.