Effect of denervation on the afferent arteriole in the SHR

To study the role the renal nerves may play in the hypertension of the SHR, we conducted a morphometric study of the afferent arteriole of spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY) which were subjected to renal denervation (or sham-operation). Methacrylate casts were made of the renal vasculature after perfusion fixation with glutaraldehyde. These vascular casts were then examined and measurements made with the scanning electron microscope (SEM). Afferent arterioles of the denervated SHR were dilated in comparison to the sham-operated SHR, but there was no difference between the afferent arteriolar diameters of the 2 groups of WKYs. However, the afferent arteriolar diameters of the SHR (either group) were smaller than those of the WKY. Renal denervation caused a reduction in systolic blood pressure compared to sham-operated in both strains of rat. We concluded that the dilation changes of afferent arterioles of denervated SHRs may be related to renal autoregulation resulting from the decreased blood pressure. However, the effect of the loss of sympathetic innervation of the arterioles cannot be ruled out.