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: 288/3/C710    most recent 00361.2004v1 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 (30) Citing Articles via Google Scholar Google Scholar Articles by Kito, Y. Articles by Sanders, K. M. Search for Related Content PubMed PubMed Citation Articles by Kito, Y. Articles by Sanders, K. M.

MEMBRANE TRANSPORTERS, ION CHANNELS, AND PUMPS

Pacemaker potentials generated by interstitial cells of Cajal in the murine intestine

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

Submitted 27 July 2004 ; accepted in final form 23 September 2004

Pacemaker potentials were recorded in situ from myenteric interstitial cells of Cajal (ICC-MY) in the murine small intestine. The nature of the two components of pacemaker potentials (upstroke and plateau) were investigated and compared with slow waves recorded from circular muscle cells. Pacemaker potentials and slow waves were not blocked by nifedipine (3 µM). In the presence of nifedipine, mibefradil, a voltage-dependent Ca²⁺ channel blocker, reduced the amplitude, frequency, and rate of rise of upstroke depolarization (dV/dt_max) of pacemaker potentials and slow waves in a dose-dependent manner (1–30 µM). Mibefradil (30 µM) changed the pattern of pacemaker potentials from rapidly rising, high-frequency events to slowly depolarizing, low-frequency events with considerable membrane noise (unitary potentials) between pacemaker potentials. Caffeine (3 mM) abolished pacemaker potentials in the presence of mibefradil. Pinacidil (10 µM), an ATP-sensitive K⁺ channel opener, hyperpolarized ICC-MY and increased the amplitude and dV/dt_max without affecting frequency. Pinacidil hyperpolarized smooth muscle cells and attenuated the amplitude and dV/dt_max of slow waves without affecting frequency. The effects of pinacidil were blocked by glibenclamide (10 µM). These data suggest that slow waves are electrotonic potentials driven by pacemaker potentials. The upstroke component of pacemaker potentials is due to activation of dihydropyridine-resistant Ca²⁺ channels, and this depolarization entrains pacemaker activity to create the plateau potential. The plateau potential may be due to summation of unitary potentials generated by individual or small groups of pacemaker units in ICC-MY. Entrainment of unitary potentials appears to depend on Ca²⁺ entry during upstroke depolarization.

pacemaker activity; slow waves; gastrointestinal motility; calcium channel

This article has been cited by other articles:

				Y. Kito, K. M. Sanders, S. M. Ward, and H. Suzuki Interstitial cells of Cajal generate spontaneous transient depolarizations in the rat gastric fundus Am J Physiol Gastrointest Liver Physiol, October 1, 2009; 297(4): G814 - G824. [Abstract] [Full Text] [PDF]

				M. J. Berridge Smooth muscle cell calcium activation mechanisms J. Physiol., November 1, 2008; 586(21): 5047 - 5061. [Abstract] [Full Text] [PDF]

				M. Kim, G. W. Hennig, K. Park, I. S. Han, T. K. Smith, S. D. Koh, and B. A. Perrino Modulation of murine gastric antrum smooth muscle STOC activity and excitability by phospholamban J. Physiol., October 15, 2008; 586(20): 4977 - 4991. [Abstract] [Full Text] [PDF]

				A. C. Bartoo, M. T. Nelson, and G. M. Mawe ATP induces guinea pig gallbladder smooth muscle excitability via the P2Y4 receptor and COX-1 activity Am J Physiol Gastrointest Liver Physiol, June 1, 2008; 294(6): G1362 - G1368. [Abstract] [Full Text] [PDF]

				B. McDonnell, R. Hamilton, M. Fong, S. M. Ward, and K. D. Keef Functional evidence for purinergic inhibitory neuromuscular transmission in the mouse internal anal sphincter Am J Physiol Gastrointest Liver Physiol, April 1, 2008; 294(4): G1041 - G1051. [Abstract] [Full Text] [PDF]

				H. Chen, T. Ordog, J. Chen, D. L. Young, M. R. Bardsley, D. Redelman, S. M. Ward, and K. M. Sanders Differential gene expression in functional classes of interstitial cells of Cajal in murine small intestine Physiol Genomics, November 14, 2007; 31(3): 492 - 509. [Abstract] [Full Text] [PDF]

				O. Bayguinov, S. M. Ward, J. L. Kenyon, and K. M. Sanders Voltage-gated Ca2+ currents are necessary for slow-wave propagation in the canine gastric antrum Am J Physiol Cell Physiol, November 1, 2007; 293(5): C1645 - C1659. [Abstract] [Full Text] [PDF]

				B. Lavoie, O. B. Balemba, M. T. Nelson, S. M. Ward, and G. M. Mawe Morphological and physiological evidence for interstitial cell of Cajal-like cells in the guinea pig gallbladder J. Physiol., March 1, 2007; 579(2): 487 - 501. [Abstract] [Full Text] [PDF]

				O. B. Balemba, T. J. Heppner, A. D. Bonev, M. T. Nelson, and G. M. Mawe Calcium waves in intact guinea pig gallbladder smooth muscle cells Am J Physiol Gastrointest Liver Physiol, October 1, 2006; 291(4): G717 - G727. [Abstract] [Full Text] [PDF]

				K. J. Park, G. W. Hennig, H.-T. Lee, N. J. Spencer, S. M. Ward, T. K. Smith, and K. M. Sanders Spatial and temporal mapping of pacemaker activity in interstitial cells of Cajal in mouse ileum in situ Am J Physiol Cell Physiol, May 1, 2006; 290(5): C1411 - C1427. [Abstract] [Full Text] [PDF]

				O. B. Balemba, M. J. Salter, T. J. Heppner, A. D. Bonev, M. T. Nelson, and G. M. Mawe Spontaneous electrical rhythmicity and the role of the sarcoplasmic reticulum in the excitability of guinea pig gallbladder smooth muscle cells Am J Physiol Gastrointest Liver Physiol, April 1, 2006; 290(4): G655 - G664. [Abstract] [Full Text] [PDF]

				S. Yun Cho, E. A. Beckett, S. A. Baker, I. Han, K. J. Park, K. Monaghan, S. M. Ward, K. M. Sanders, and S. D. Koh A pH-sensitive potassium conductance (TASK) and its function in the murine gastrointestinal tract J. Physiol., May 15, 2005; 565(1): 243 - 259. [Abstract] [Full Text] [PDF]