In:
Kidney and Blood Pressure Research, S. Karger AG, Vol. 10, No. 5 ( 1987), p. 272-282
Abstract:
The purpose of the present experiments was to determine the renovascular effects of the adenosine agonists N-ethyl-carboxamide adenosine (NECA), N 〈 sup 〉 6 〈 /sup 〉 -cyclohexyl adenosine (CHA) and 2-chloro adenosine (2-CLA). The diameter of pre- and postglomerular vessels in the split hydronephrotic kidney of Inactin®-anesthetized rats was measured by in vivo television microscopy. All metabolically stable adenosine agonists were topically applied into the renal tissue bath. NECA, a preferential A 〈 sub 〉 2 〈 /sub 〉 adenosine receptor agonist, induced dose-dependent marked pre- and slight postglomerular vasodilation except for a small constrictory effect on the afferent arteriole near the glomerulus. Application of CHA, a selective A 〈 sub 〉 1 〈 /sub 〉 adenosine receptor agonist, led to a vasoconstriction of all preglomerular vessels, the extent of which was greatest at the most distal segment of the afferent arteriole. 2-CLA, a nonselective agonist, produced a small decrease in diameter in all preglomerular vessels, a marked constriction of the afferent arteriole at sites near the glomerulus, and a slight dilation of postglomerular vessels. Glomerular blood flow (GBF) was increased by NECA, and decreased by CHA and 2-CLA. The effects of CHA in reducing GBF were greater than those of 2-CLA. From these experiments it is concluded that vascular 〈 i 〉 A 〈 /i 〉 〈 sub 〉 1 〈 /sub 〉 and A 〈 sub 〉 2 〈 /sub 〉 adenosine receptors are present in the kidney and that activation of A 〈 sub 〉 1 〈 /sub 〉 receptors is associated with preglomerular vasoconstriction only, whereas activation of A 〈 sub 〉 2 〈 /sub 〉 receptors mediates pre- and postglomerular vasodilation with a lack of vasodilatory response of the distal afferent arteriole. Furthermore, these data indicate that nonselective occupation of both receptor subclasses is associated with marked vasoconstriction of the afferent arteriole and little vasodilation of the efferent arteriole.
Type of Medium:
Online Resource
ISSN:
1420-4096
,
1423-0143
Language:
English
Publisher:
S. Karger AG
Publication Date:
1987
detail.hit.zdb_id:
1482922-8
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