Planimetric Study on The Renal Arteriolar Narrowing in The Early Stage of Hypertension

For clarifying the role of renal arteriolar changes in the development of human hypertension, a planimetric study was performed on the renal biopsy specimens obtained from 65 patients with chronic glomerulonephritis (CGN) and 12 patients with juvenile hypertension (JH). The ratio (R) of the inside luminal area to the outside one measured on tangenital sections of the renal arterioles was used as an index of renal arteriolar narrowing. The results obtained are as follows: In the CGN groups, which was deviled into minimal, slight, moderate, and advanced subgroups according to their degrees of glomerular changes and clinical findings, R value was significantly decreased in the slight and moderate groups comparing to that of the minimal one. No elevation of blood pressure was yet present in those groups. The degree of renal arteriolar narrowing was much more severe in the advanced group associated with significantly high blood pressure. Main histopathological features of the renal arteriole consisted of either fibrous degeneration and thickening or muscular hypertrophy. Those morphological and clinical renal findings suggest that the renal arteriolar narrowing may play an important role in both development of renal hypertension and progression of CGN. In the JH group, similar renal arteriolar change to those in the former group were observed. R values were comparable to those of various stages of CGN. There was no quantative differ-ence between JH and CGN groups noted in the histological findings of the renal arterioles. Although, in this group, there was no significant relation between R values and systolic blood pressure or age, arteriolar narrowing was observed to some extent even in the early stage of primary hypertension. Those results further suggest a possibility that all of the arteriolar changes may not secondarily be brought about but may occur rather primarily or precede an onset of clinical hypertension acting as its accelerating factor.