Effects of Angiotensin II on Isolated Rabbit Afferent Arterioles

Abstract

ABSTRACT-We examined the effects of angiotensin II (Ang II) on isolated rabbit afferent arterioles to assess the direct effect of Ang II at the resistance vessel level in the kidney. We microdissected the superficial afferent arteriole from the kidney of New Zealand White rabbits. The afferent arteriole was cannulated with a micropipette system, and the intraluminal pressure was set at 80 mmHg. Ang II did not change the lumen diameter of the afferent arterioles. After the afferent arterioles were pretreated with aspirin DL-lysine or indomethacin, Ang II (10-' M) caused transient vasoconstriction in the afferent arterioles. Ang II (10-' M) caused persistent constriction in the afferent arterioles pretreated with 1VG-nitro-L-arginine (10-4 M). Physiological doses of Ang II decresed the lumen diameter of the isolated afferent arterioles pretreated with A7'-nitro-L-arginine and aspirin DL-lysine. Dup753 (10-6 M), an AT1-receptor antagonist, abolished the vasoconstrictor effects of Ang II. These findings suggest that the isolated rabbit afferent arteriole has AT1 receptors, and the vasoconstrictor response of Ang II is counteracted by vasodilatory prostaglandins and nitric oxide.

Nitrite-derived nitric oxide formation following ischemia-reperfusion injury in kidney

“…NO antagonizes the vasoconstrictive effect of angiotensin II on the afferent arterioles (20,48) and helps to maintain glomerular filtration rate, renal plasma flow (16), and sodium regulation. NO may also play an important pathophysiological role during renal ischemia (15), but the precise role of NO in renal ischemia-reperfusion injury is not clear.…”

The Intrarenal Renin-Angiotensin System: From Physiology to the Pathobiology of Hypertension and Kidney Disease

“…Ito et al (1991Ito et al ( , 1993, and Yoshida et al (1994) showed that inhibition of nitric oxide synthesis markedly augmented the afferent arteriolar responses to Ang II, indicating that high levels of nitric oxide may be present in the dissected afferent arterioles perfused with cell-free solutions. Studies using the in vitro blood-perfused juxtamedullary nephron preparation (Carmines et al, 1986;Ichihara et al, 1997), renal tissue transplantation into hamster cheek pouch (Click et al, 1979), and hydronephrotic rat kidneys (Steinhausen et al, 1987;Dietrich et al, 1991;Loutzenhiser et al, 1991;Inman et al, 1995) also showed similar results.…”

Eicosanoid regulation of the renal vasculature

“…Although prostaglandins buffer the whole kidney renal blood flow responses to angiotensin II, there may be differences between superficial and juxtamedullary afferent arteriolar populations. Microdissected superficial afferent arterioles demonstrate an enhanced responsiveness to angiotensin II during COX inhibition (81,179). In contrast, the angiotensin II vasoconstrictor response of juxtamedullary afferent arterioles (67) and descending vasa recta is not altered by COX blockade (56).…”