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This Article Full Text Full Text (PDF) Supplemental Video All Versions of this Article: 294/3/F656    most recent 00493.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Zhang, Q. Articles by Pallone, T. L. Search for Related Content PubMed PubMed Citation Articles by Zhang, Q. Articles by Pallone, T. L.

Membrane current oscillations in descending vasa recta pericytes

¹Department of Medicine, ²Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland; and ³Department of Chemical and Biological Engineering, Tufts University, Medford, Massachusetts

Submitted 19 October 2007 ; accepted in final form 30 December 2007

We investigated the origin of spontaneous transient inward current (STIC) oscillations in descending vasa recta (DVR) pericytes. In cells clamped at –80 mV, angiotensin II (ANG II; 10 nmol/l) induced oscillations with mean amplitude and frequency of –65.5 pA and 1.2 Hz. Simultaneous recording of cytoplasmic calcium ([Ca²⁺]_CYT) and membrane current oscillations verified their synchrony and the correlation of their amplitudes. Confocal recording in fluo-4-loaded DVR showed that ANG II can induce either stable pericyte [Ca²⁺]_CYT elevation or oscillations, while decreasing adjacent endothelial [Ca²⁺]_CYT. Oscillating currents reversed sign at –30.2 mV and were blocked by niflumic acid, implicating charge transfer via Cl^– ion. Removal of extracellular Ca²⁺, blockade of Ca²⁺ influx with SKF96365 (30 µmol/l), ryanodine (30 µmol/l), or caffeine (10 mmol/l) inhibited oscillations. In contrast, they were insensitive to removal of extracellular Na⁺ and exposure to either nifedipine (1 µmol/l) or 2-aminoethoxydiphenyl borate (10 µmol/l). Ouabain (100 nmol/l) increased basal pericyte [Ca²⁺]_CYT and the frequency of resting STICs but did not affect the larger oscillations that followed ANG II stimulation. We conclude that [Ca²⁺]_CYT oscillations stimulate Cl^– currents. The former are most likely maintained by repetitive cycles of ryanodine-sensitive SR Ca²⁺ release and SKF96365-sensitive store refilling.

terminal resistance vessels; blood flow; renal medulla

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				A. Edwards and T. L. Pallone Mechanisms underlying angiotensin II-induced calcium oscillations Am J Physiol Renal Physiol, August 1, 2008; 295(2): F568 - F584. [Abstract] [Full Text] [PDF]