Early narrowed afferent arteriole is a contributor to the development of hypertension.

Abstract

The kidney is probably critically involved in the development of essential hypertension, as in many genetic models of hypertension. We have investigated whether a narrowed renal afferent arteriole is involved in the pathogenesis of hypertension in spontaneously hypertensive rats. Systolic blood pressure of 37 F 2 generation spontaneously hypertensive rats/Wistar-Kyoto rats was measured at age 7 weeks. The right kidney was removed, and lumen diameter and media cross-sectional area of the afferent arterioles were measured after having been fixed while relaxed and under a transmural pressure of 100 mm Hg. The uninephrectomized rats continued until age 23 weeks, when mean blood pressure was measured. Mean blood pressure at 23 weeks was negatively A increasing amount of evidence supports a critical role for the kidney in the pathogenesis of essential hypertension.15 Key early observations concerned retrospective studies indicating that after kidney transplantation the blood pressure of recipients appeared to correlate with the blood pressure of donors. 68 More recently, the introduction of cyclosporine treatment with its own hypertensive effect has made it difficult to determine whether the blood pressure of donors influences the subsequent blood pressure of recipients. On the other hand, animal studies offer a means of examining this question in detail, 2 -3 and indeed, such studies have provided further strong evidence in support of the kidney playing a primary role in the development of genetic hypertension.Renal cross-transplantation experiments between inbred genetically hypertensive and normotensive rat strains show that kidneys taken from hypertensive donors cause the development of hypertension when transplanted to normotensive recipients.911 This is also the case if the donor rat has been kept normotensive with antihypertensive treatment until transplantation is performed, 11 suggesting that the renal effects are not secondary to hypertension-induced lesions but that a primary defect that can cause the blood pressure to increase may reside in the kidney. Received February 7, 1994; accepted in revised form May 26, 1994.From the Danish Biomembrane Research Centre and Department of Pharmacology, Aarhus University (Denmark), and Department of Medicine, University of Leicester (UK).Correspondence to Dr Niels Korsgaard, Department of Pharmacology, Aarhus University, University Park 240,8000 Aarhus C, Denmark.O 1994 American Heart Association, Inc.correlated with lumen diameter at 7 weeks. Quartile analysis based on lumen diameter at 7 weeks showed that compared with rats in the top lumen diameter quartile, rats in the bottom lumen diameter quartile had a reduced media cross-sectional area at 7 weeks (17%), the same systolic blood pressure at 7 weeks, and an increased (16%) mean blood pressure at 23 weeks. We conclude that in spontaneously hypertensive rats a narrowed lumen of distal afferent arterioles at 7 weeks contributes to later development of increased blood pressure. This reduced lumen could be c...

Prevention and regression of hypertension: role of renal microvascular protection

“…It is well recognized that transplantation of kidneys from SHR to WKY results in transfer of the hypertension, whereas transplantation from WKY to SHR results in normalization of the blood pressure, [39][40][41] consistent with a central role for the kidney in the pathogenesis of hypertension. To extend these findings, Norrelund et al 42 performed studies in which the progeny of a cross between hypertensive and normotensive animals were themselves crossed to produce an F2-generation. Interestingly, it was found that a narrowed afferent arteriole in young F2-SHR/WKY was associated with the later development of high blood pressure, suggesting a role for this phenotype in the pathogenesis of hypertension.…”

Microcirculation in Hypertension

“…An increase in the media-to-lumen ratio in mesenteric small resistance arteries has been observed in SHR at a prehypertensive stage (4 weeks of age). 12 Norrelund et al 13 found that renal afferent arterioles are narrowed at a very young age in SHR. Interestingly, there was no correlation between renal afferent arteriolar diameter and blood pressure in SHR at 7 weeks of age, but the lumen reduction at 7 weeks correlated with blood pressure subsequently measured at 23 weeks.…”

“…Interestingly, there was no correlation between renal afferent arteriolar diameter and blood pressure in SHR at 7 weeks of age, but the lumen reduction at 7 weeks correlated with blood pressure subsequently measured at 23 weeks. Norrelund et al 13 concluded that 1 or more of the genetic determinants that influence blood pressure in SHR do so by influencing the diameters of renal afferent arterioles.…”

Experimental Animal Models for Retinal and Choroidal Diseases

“…Animal models, in vitro experiments, and clinical studies have demonstrated that microcirculatory changes such as arteriolar narrowing, enhanced vasoconstriction, reduced vasodilator responses and arteriolar or capillary diminishing are the earliest changes in the pathogenesis of hypertension. It has been considered that the microcirculation plays a critical role in the pathogenesis of hypertension [99][100][101][102][103][104]. …”