The relative preservation of responsiveness to ET-1 and increased binding affinity suggest endogenous ET-1 plays a role in postischemic renal vasoconstriction.
ET-1 may mediate postischemic renal vasoconstriction in animals; hypothesis-generating for antagonists in human ischemic AKI.
Reperfusion after renal ischemia is characterized by a preglomerular vasoconstriction. As endothelin-1 (ET-1) is a potent preglomerular vasoconstrictor, we designed a study to investigate the role of ET-1 in postischemic renal vasoconstriction. Renal ischemia was induced by 45 min of left renal artery clamping in anesthetized rats. After ischemia, renal blood flow was restored to only 61 +/- 4% of its preischemic value. The sensitivity to exogenous ET-1 after renal ischemia was decreased, but much less than the sensitivity to angiotensin II, which almost lost its vasoconstrictor effect, and to norepinephrine, which became a vasodilator. In addition, the binding affinity of [125I]ET-1 in the kidney increased significantly after renal ischemia, despite no change in the density of binding sites. These findings may be in favor of a role of endogenous ET-1 in postischemic renal vasoconstriction.
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Clozel et al. (1991) studied this question.
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