Inhibition of adenosine1 receptor-mediated preglomerular
vasoconstriction in at1areceptor deficient mice.
Traynor, Timothy, Tianxin Yang, Yuning G. Huang, Lois Arend, Michael
I. Oliverio, Thomas Coffman, Josie P. Briggs, and J[umlaut]urgen
Schnermann.
1Departments of Physiology and Internal Medicine, University of
Michigan, Ann Arbor, Michigan, 2DKUHD, NIDDK, NIH, Bethesda,
Maryland, and 3Department of Medicine, Duke University, Durham, North
Carolina
APStracts 5:0153F, 1998.
The effect of the adenosine1 receptor agonist cyclohexyladenosine
(CHA) on glomerular vascular reactivity was studied in male
angiotensin II 1A (AT1A) receptor knockout mice (9). Vascular
reactivity was assessed as the response of stop flow pressure (PSF)
to infusion of CHA into loops of Henle using micropuncture
techniques. In AT1A +/+ mice at ambient arterial blood pressure (96.7
+/- 2.8 mm Hg), the presence of CHA (10 -5 M) in the perfusate
increased PSF responses from 6.8 +/- 0.6 to 14.3 +/- 0.9 mm Hg when
the loop of Henle of the index nephron was perfused, and from 0.7 +/-
0.3 to 12.3 +/- 1.0 mm Hg when the loop of an adjacent nephron was
perfused. At reduced arterial blood pressure (82.8 +/- 1.3 mm Hg)
index nephron perfusion with CHA increased PSF responses from 4.5 +/-
0.3 mm Hg to 9.4 +/- 0.4 mm Hg. In AT1A -/- mice with a mean arterial
blood pressure of 80 +/- 1.9 mm Hg, CHA increased PSF responses only
from 0.1 +/- 0.3 to 3.6 +/- 0.54 mm Hg during index nephron perfusion
and from 0.25 +/- 0.2 to 2.7 +/- 0.55 mm Hg during adjacent nephron
perfusion, significantly less than in wild type animals (p<0.001).
Responses to CHA were intermediate in AT1A +/- mice. Thus, AT1A
receptor knockout mice show a markedly reduced constrictor response
to CHA both in the presence and absence of simultaneous activation of
the TGF system. These data support the notion of a functional
interaction between adenosine and angiotensin II in the regulation of
afferent arteriolar tone.
Received 13 April 1998; accepted in final form 27 March 1998.
APS Manuscript Number F83-8.
Article publication pending Am. J. Physiol. (Renal Physiology).
ISSN 1080-4757 Copyright 1998 The American Physiological Society.
Published in APStracts on 21 September 1998