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Adaptation of Descending Vasa Recta after Renal Ischemia
Author(s) -
Pallone Thomas,
Zhang Zhong,
Payne Kristie
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.808.21
Subject(s) - kidney , ischemia , vasa recta , medicine , renal artery , chemistry , patch clamp , clamp , hyperpolarization (physics) , blockade , vasoconstriction , endocrinology , electrophysiology , mechanical engineering , clamping , receptor , organic chemistry , nuclear magnetic resonance spectroscopy , engineering
Renal ischemia‐reperfusion (IR) can lead to adaptations that protect the kidney from future insults. Descending vasa recta (DVR) supply all renal blood flow to the renal medulla. We tested whether cross clamp of the renal artery leads to adaptations of DVR pericytes, endothelia and syncytial conduction between the cells. The left renal artery was cross‐clamped for 30 minutes. Two days later DVR were harvested from right and left kidneys. NO generation indicated by DAF fluorescence increased markedly in IR treated DVR. In 20 minutes DAF fluorescence increased by 23±3% vs 5±4% in controls (P<0.01, n=7 each). The difference was eliminated by iNOS inhibition (1400W, 1 uM).Similarly blockade of iNOS by 1400W constricted post ischemic DVR more than controls. The percent reduction of luminal diameter by AngII (10 nM) was reduced in IR pretreated DVR, 28±6% vs 54±8% (P<0.01, n=5 each). In dual patch clamp studies, membrane potentials were hyperpolarized; pericytes (‐49±2 vs ‐58±4 mV, P<0.05) and endothelia (‐44±3 vs ‐61± 4 mV, P<0.01). Injection of hyperpolarizing current (‐400 pA) into a pericyte led to greater hyperpolarization of adjacent pericytes (‐55±4 vs ‐77±3 mV, P<0.01 n=7) or endothelia (‐38±5 vs ‐62±4 mV, P<0.01, n=7). We conclude that DVR adapt after ischemia‐reperfusion in several ways. NO generation by iNOS increases. Agonist induced vasoconstriction is blunted. Membrane potentials of endothelia and pericytes hyperpolarize. Conduction of hyperpolarizing current between pericytes and across myoendothelial junctions leads to larger reduction of membrane potential. These changes uniformly favor preservation of medullary blood flow and defense of tissue oxygenation.