HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Services Email this article to a friend Similar articles in this journal 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 Russ, U. Articles by Quast, U. Search for Related Content PubMed PubMed Citation Articles by Russ, U. Articles by Quast, U.

Pharmacological evidence for a K_ATP channel in renin-secreting cells from rat kidney

Ulrich Russ, Ulrich Rauch and Ulrich Quast

Openers of the ATP-sensitive potassium channel (K_ATP channel) increase and blockers decrease renin secretion. Here we report the effects of levcromakalim (LCRK, a channel opener) and glibenclamide (GBC, a blocker) on membrane potential, whole-cell current and the cytoplasmic Ca²⁺ concentration of renin-secreting cells (RSC). Studies were performed on afferent arterioles from the kidney of Na⁺-depleted rats.

As monitored with the fluorescent oxonol dye DiBAC₄(3), LCRK (0·3 and 1 µM) induced a hyperpolarization of ~15 mV which was abolished by GBC (1 µM).

Whole-cell current-clamp experiments showed that RSC had a membrane potential of -61 ± 1 mV (n = 16). LCRK (1 µM) induced a hyperpolarization of 9·9 ± 0·2 mV (n = 16) which, in the majority of cells, decreased slowly with time.

Capacitance measurements showed a strong electrical coupling of the cells in the preparation.

At -60 mV, LCRK induced a hyperpolarizing current in a concentration-dependent manner with an EC₅₀ of 152 ± 31 nM and a maximum current of about 200 pA.

Application of GBC (1 µM) produced no effect; however, when applied after LCRK (300 nM), GBC inhibited the opener-induced hyperpolarizing current with an IC₅₀ of 103 ± 36 nM.

LCRK (0·3 and 1 µM) did not significantly affect the cytoplasmic Ca²⁺ concentration either at rest or after stimulation by angiotensin II.

The data show that LCRK induces a GBC-sensitive hyperpolarizing current in rat RSC. This current presumably originates from the activation of K_ATP channels which pharmacologically resemble those in vascular smooth muscle cells. The stimulatory effect of K_ATP channel opening on renin secretion is not mediated by a decrease in intracellular Ca²⁺ concentration.

This article has been cited by other articles:

				F. Schweda, U. Friis, C. Wagner, O. Skott, and A. Kurtz Renin Release Physiology, October 1, 2007; 22(5): 310 - 319. [Abstract] [Full Text] [PDF]

				C. Cao, W. Lee-Kwon, E. P. Silldorff, and T. L. Pallone KATP channel conductance of descending vasa recta pericytes Am J Physiol Renal Physiol, December 1, 2005; 289(6): F1235 - F1245. [Abstract] [Full Text] [PDF]

				A. Leichtle, U. Rauch, M. Albinus, P. Benohr, H. Kalbacher, A. F Mack, R. W Veh, U. Quast, and U. Russ Electrophysiological and molecular characterization of the inward rectifier in juxtaglomerular cells from rat kidney J. Physiol., October 15, 2004; 560(2): 365 - 376. [Abstract] [Full Text] [PDF]

				U. G. Friis, F. Jorgensen, D. Andreasen, B. L. Jensen, and O. Skott Molecular and Functional Identification of Cyclic AMP-Sensitive BKCa Potassium Channels (ZERO Variant) and L-Type Voltage-Dependent Calcium Channels in Single Rat Juxtaglomerular Cells Circ. Res., August 8, 2003; 93(3): 213 - 220. [Abstract] [Full Text] [PDF]

				H. Malhi, A. N. Irani, P. Rajvanshi, S. O. Suadicani, D. C. Spray, T. V. McDonald, and S. Gupta KATP Channels Regulate Mitogenically Induced Proliferation in Primary Rat Hepatocytes and Human Liver Cell Lines. IMPLICATIONS FOR LIVER GROWTH CONTROL AND POTENTIAL THERAPEUTIC TARGETING J. Biol. Chem., August 18, 2000; 275(34): 26050 - 26057. [Abstract] [Full Text] [PDF]