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) All Versions of this Article: 293/5/C1645    most recent 00165.2007v1 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 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 Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Bayguinov, O. Articles by Sanders, K. M. Search for Related Content PubMed PubMed Citation Articles by Bayguinov, O. Articles by Sanders, K. M.

MEMBRANE TRANSPORTERS, ION CHANNELS, AND PUMPS

Voltage-gated Ca²⁺ currents are necessary for slow-wave propagation in the canine gastric antrum

Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada

Submitted 17 April 2007 ; accepted in final form 7 September 2007

Electrical slow waves determine the timing and force of peristaltic contractions in the stomach. Slow waves originate from a dominant pacemaker in the orad corpus and propagate actively around and down the stomach to the pylorus. The mechanism of slow-wave propagation is controversial. We tested whether Ca²⁺ entry via a voltage-dependent, dihydropyridine-resistant Ca²⁺ conductance is necessary for active propagation in canine gastric antral muscles. Muscle strips cut parallel to the circular muscle were studied with intracellular electrophysiological techniques using a partitioned-chamber apparatus. Slow-wave upstroke velocity and plateau amplitude decreased from the greater to the lesser curvature, and this corresponded to a decrease in the density of interstitial cells of Cajal in the lesser curvature. Slow-wave propagation velocity between electrodes impaling cells in two regions of muscle and slow-wave upstroke and plateau were measured in response to experimental conditions that reduce the driving force for Ca²⁺ entry or block voltage-dependent Ca²⁺ currents. Nicardipine (0.1–1 µM) did not affect slow-wave upstroke or propagation velocities. Upstroke velocity, amplitude, and propagation velocity were reduced in a concentration-dependent manner by Ni²⁺ (1–100 µM), mibefradil (10–30 µM), and reduced extracellular Ca²⁺ (0.5–1.5 mM). Depolarization (by 10–15 mM K⁺) or hyperpolarization (10 µM pinacidil) also reduced upstroke and propagation velocities. The higher concentrations (or lowest Ca²⁺) of these drugs and ionic conditions tested blocked slow-wave propagation. Treatment with cyclopiazonic acid to empty Ca²⁺ stores did not affect propagation. These experiments show that voltage-dependent Ca²⁺ entry is obligatory for the upstroke phase of slow waves and active propagation.

interstitial cells of Cajal; gastric motility; calcium channels; pacemaker activity

This article has been cited by other articles:

				A. S. Forrest, G. W. Hennig, S. Jokela-Willis, C. D. Park, and K. M. Sanders Prostaglandin regulation of gastric slow waves and peristalsis Am J Physiol Gastrointest Liver Physiol, June 1, 2009; 296(6): G1180 - G1190. [Abstract] [Full Text] [PDF]

				J. G. McCarron, M. L. Olson, S. Currie, A. J. Wright, K. I. Anderson, and J. M. Girkin Elevations of intracellular calcium reflect normal voltage-dependent behavior, and not constitutive activity, of voltage-dependent calcium channels in gastrointestinal and vascular smooth muscle J. Gen. Physiol., April 1, 2009; 133(4): 439 - 457. [Abstract] [Full Text] [PDF]