Regression of the baroreceptor resetting in hypertension of long duration in rats

1. The extent of reversal of baroreceptor resetting after pressure normalization was studied in rats with renal hypertension of up to 6 months duration. The aortas of these rats when compared with those of 2 month hypertensive rats were thicker (44%) and had a larger calibre (29%). 2. The more severe morphological alterations found in the 6 month hypertensive rats did not interfere with the reversibility of the resetting process. The entire range of pressure for baroreceptor activation showed a small downward displacement after 1 h and was functioning at a completely normal pressure 6 h after pressure normalization. 3. The data show that reversal of resetting from hypertension is a very rapid process that is independent of the duration of hypertension and the severity of morphological lesions. Moreover, they indicate that reversal is a permanent phenomenon because it was also observed after 2 days of pressure normalization.