Is hypertrophy of the walls of pre-glomerular vessels responsible for hypertension in spontaneously hypertensive rats?

This paper reviews briefly the experimental support for the hypothesis that hypertrophy of the walls of pre-glomerular vessels may occur in human essential hypertension and in spontaneously hypertensive rats (SHR) and that it may be the primary stimulus to the development of the hypertension. Pre-glomerular hypertrophy with resultant lumen narrowing will simulate narrowing of the main renal artery haemodynamically, as originally proposed by Goldblatt. In SHR there is strong evidence for increased wall thickness of the intra-renal arteries and for structurally based narrowing of the lumen of the afferent arterioles. Compatible with these morphological findings, SHR have increased resting renal vascular resistance and it has been shown experimentally that the extent of increased renal resistance is correlated with the extent of hypertension development. Increased renal vascular resistance occurs early in human essential hypertension too, but direct evidence for pre-glomerular structural changes is lacking and will be difficult to gather. The causes of the pre-glomerular structural changes in SHR remain to be determined, but they do not appear to be secondary to the hypertension.