Segmental effects of norepinephrine and angiotensin II on isolated renal microvessels

Abstract

Interlobular arteries and superficial afferent and efferent arterioles were isolated from rabbit kidney, and the effects of intraluminal pressure, norepinephrine (NE), and angiotensin II (ANG II) on lumen diameter were examined. A single microvessel was dissected and one end was cannulated. The other end of the vessel was occluded and lumen diameter was measured at fixed intraluminal pressures. With step increases in intraluminal pressure over the range of 70-180 mmHg, lumen diameters of the interlobular arteries and afferent arterioles remained constant or decreased by up to 11%. In contrast, lumen diameters of efferent arterioles continued to increase as intraluminal pressure was elevated. In all three vessels NE (10(-9) to 10(-5) M) caused a dose-dependent decrease in lumen diameter. However, only the efferent arteriole responded to ANG II (10(-12) to 10(-8) M). The contractile response of the efferent arteriole to NE or ANG II was localized to the first 50-75 micrometers of the vessel as it emerged from the glomerulus. This finding suggests that smooth muscle cells are located only in this portion of the efferent arteriole. It is concluded that at least part of the autoregulation of renal blood flow can be explained by a myogenic mechanism in preglomerular vessels and that ANG II acts primarily on postglomerular segments of the rabbit renal microcirculation.

Protective Effect of Benidipine against the Development of Glomerular Sclerosis in Experimental Nephrotic Syndrome

“…Many authors suggested that anti hype rten sive agents such as ACE in hibitors, which reduce glomerular capillary hydraulic pressure, improve proteinuria and glomerular sclerosis (18,(20)(21)(22)(23). On the other hand, it has been reported that Ca-channel blockers show more selective relaxation of renal afferent arterioles than renal efferent arterioles (24,25).…”

Validation of an integrative mathematical model of dehydration and rehydration in virtual humans

“…The glomerular capillary pressure is profoundly affected by afferent and efferent arteriolar conditions, notably their conductance and relative pressures. These are controlled by tubuloglomerular feedback (TGF) and angiotensin II (AII) (Edwards 1983), respectively, and by α 1 ‐adrenergic activity in both zones (Zimmerman et al. 1984; Kon 1989).…”

What Have We Learned from Gene Targeting Studies for the Renin Angiotensin System of the Kidney?

“…Therefore, mammals must maintain a constant GFRregardless of an extracellular fluid (ECF) volume status in order to rid the body of toxic wastes. Ang II contributes to these features of mammalian kidneys through its constrictive action on renal arteries (20)(21)(22) and its regulatory effect on iron transports (23)(24)(25). Recently, Okubo et al (26) and Kihara et al (27) reported that Agt-I-mice have severely impaired ability for urinary concentration during experimental ECF volume depletion.…”