QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal 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 CHANG, W. Articles by LORETZ, C. A. Search for Related Content PubMed Articles by CHANG, W. Articles by LORETZ, C. A.

Journal of Experimental Biology 169,87-104 (1992)
Published by Company of Biologists 1992

Activation by Membrane Stretch and Depolarization of an Epithelial Monovalent Cation Channel from Teleost Intestine

WENHAN CHANG ¹ and CHRISTOPHER A. LORETZ ¹

¹ Department of Biological Sciences, State University of New York at Buffalo, Buffalo, NY 14260, USA

The intestine of euryhaline teleosts is an important osmoregulatory organ which actively absorbs Na⁺, Cl^- and water from the lumen. This ion-transporting epithelium experiences a variety of physical stimuli resulting from variations in luminal osmolality and distension and from peristaltic contractions. Using patchclamp techniques in the inside-out configuration, single stretch-activated channels (SA channels) were identified and characterized. These SA channels had a conductance of about 67 pS in symmetrical solutions containing 140 mmoll^-1 NaCl and were permeable to both Na⁺ and K⁺ (P_Na/P_K0.83) but not to anions. In excised, inside-out membrane patches, channel activity could be enhanced in the absence of membrane tension by strong depolarization of the membrane potential (V_m) to between 0 mV and + 90 mV, with V_o [V_m at which the single-channel open probability (P_o)=0.5] at + 25.7 mV. In the presence of membrane tension, the voltage-dependence of channel activity was shifted into the physiological range of V_m. Each kPa (10 cmH₂O) of applied pressure (P) generated the same effect on P_o as a membrane depolarization of 49 mV. Membrane tension also increased the single-channel current and single-channel conductance in a dose-dependent manner. The kinetic data suggest that this channel has two open states and three closed states. Both stretch- and depolarization-induced increases in P_o were attributed to prolongation of the lifetime of the longer open state. Possible physiological roles for this channel include the cellular uptake of Na+ from the lumen as part of the salt and water absorptive process or a yet undefined involvement in cell volume regulation.

Key words: stretch-activated channel, fish intestinal epithelium, patch-clamp, Gillichthys mirabilis

Accepted on April 22, 1992

This article has been cited by other articles:

				C. Duranton, E. Mikulovic, M. Tauc, M. Avella, and P. Poujeol Potassium channels in primary cultures of seawater fish gill cells. I. Stretch-activated K+ channels Am J Physiol Regulatory Integrative Comp Physiol, November 1, 2000; 279(5): R1647 - R1658. [Abstract] [Full Text] [PDF]

				Z. Gil, S. D. Silberberg, and K. L. Magleby Voltage-induced membrane displacement in patch pipettes activates mechanosensitive channels PNAS, December 7, 1999; 96(25): 14594 - 14599. [Abstract] [Full Text] [PDF]