Selective distribution of medial thickening in the renal vessels in experimental hypertension.

Direct effects, especially the distribution of medial thickening due to chronic hypertension on the renal arterial tree, were examined pathologically and morphometrically in cats with one-kidney DOCA-salt hypertension. Twenty-one adult male cats were divided into three groups: (i) an experimental group of one-kidney DOCA-salt hypertension (12 cats): (ii) a uninephrectomized group without administration of DOCA and salt (four cats); and (iii) a group without uninephrectomy and administration of DOCA and salt (five cats). The duration of hypertension varied from 3 weeks to 4 months and the aortic blood pressure was monitored every 5 min. The increase of mean blood pressure (MBP) of the experimental group was 15-44 mmHg. A significant medial thickening of the right renal arterial tree was evaluated by a comparison of the right and left regression lines of each case between the midwall radius (R) and medial thickness (D) of arteries in a distended state. The evaluation was made separately for arteries with R values above or below 40 microns, because a regression line between R and D showed a maximum bend at a level of R from 30 to 40 microns. The arteries of the right kidney with a diameter less than 40 microns, corresponding to the interlobular arteries and afferent arterioles, showed significant medial thickening in six cases. Medial thickening was absent in other cats of the experimental group and cats of a control group given uninephrectomy alone. Increase of MBP during the hypertensive phase of these six cases was above 34.6 mmHG and all values of other cats without medial thickening were below this level.(ABSTRACT TRUNCATED AT 250 WORDS)