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Descending vasa recta pericytes express voltage operated Na + conductance in the rat
Author(s) -
Zhang Zhong,
Cao Chunhua,
LeeKwon Whaseon,
Pallone Thomas L.
Publication year - 2005
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2005.091538
Subject(s) - depolarization , biophysics , repolarization , chemistry , conductance , nifedipine , veratridine , tetrodotoxin , membrane potential , extracellular , patch clamp , electrophysiology , sodium , medicine , calcium , sodium channel , biology , biochemistry , mathematics , organic chemistry , combinatorics
We studied the properties of a voltage‐operated Na + conductance in descending vasa recta (DVR) pericytes isolated from the renal outer medulla. Whole‐cell patch‐clamp recordings revealed a depolarization‐induced, rapidly activating and rapidly inactivating inward current that was abolished by removal of Na + but not Ca + from the extracellular buffer. The Na + current ( I Na ) is highly sensitive to tetrodotoxin (TTX, K d = 2.2 n m ) . At high concentrations, mibefradil (10 μ m ) and Ni + (1 m m ) blocked I Na . I Na was insensitive to nifedipine (10 μ m ). The L‐type Ca + channel activator FPL‐64176 induced a slowly activating/inactivating inward current that was abolished by nifedipine. Depolarization to membrane potentials between 0 and 30 mV induced inactivation with a time constant of ∼1 ms. Repolarization to membrane potentials between −90 and −120 mV induced recovery from inactivation with a time constant of ∼11 ms. Half‐maximal activation and inactivation occurred at −23.9 and −66.1 mV, respectively, with slope factors of 4.8 and 9.5 mV, respectively. The Na + channel activator, veratridine (100 μ m ), reduced peak inward I Na and prevented inactivation. We conclude that a TTX‐sensitive voltage‐operated Na + conductance, with properties similar to that in other smooth muscle cells, is expressed by DVR pericytes.