title: Characterization of slow waves generated by myenteric interstitial cells of Cajal of the rabbit small intestine.
abstract: Slow waves (slow wavesICC) were recorded from myenteric interstitial cells of Cajal (ICC-MY) in situ in the rabbit small intestine, and their properties were compared with those of mouse small intestine. Rabbit slow wavesICC consisted of an upstroke depolarization followed by a distinct plateau component. Ni(2+) and nominally Ca(2+)-free solutions reduced the rate-of-rise and amplitude of the upstroke depolarization. Replacement of Ca(2+) with Sr(2+) enhanced the upstroke component but decreased the plateau component of rabbit slow wavesICC. In contrast, replacing Ca(2+) with Sr(2+) decreased both components of mouse slow wavesICC. The plateau component of rabbit slow wavesICC was inhibited in low-extracellular-Cl(-)-concentration (low-[Cl(-)]o) solutions and by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), an inhibitor of Cl(-) channels, cyclopiazonic acid (CPA), an inhibitor of internal Ca(2+) pumps, or bumetanide, an inhibitor of Na(+)-K(+)-2Cl(-) cotransporter (NKCC1). Bumetanide also inhibited the plateau component of mouse slow wavesICC. NKCC1-like immunoreactivity was observed mainly in ICC-MY in the rabbit small intestine. Membrane depolarization with a high-K(+) solution reduced the upstroke component of rabbit slow wavesICC. In cells depolarized with elevated external K(+), DIDS, CPA, and bumetanide blocked slow wavesICC. These results suggest that the upstroke component of rabbit slow wavesICC is partially mediated by voltage-dependent Ca(2+) influx, whereas the plateau component is dependent on Ca(2+)-activated Cl(-) efflux. NKCC1 is likely to be responsible for Cl(-) accumulation in ICC-MY. The results also suggest that the mechanism of the upstroke component differs in rabbit and mouse slow wavesICC in the small intestine.
authors.affiliation: Department of Pharmacology, Faculty of Medicine, Saga University, Nabeshima, Saga, Japan; Department of Cell Physiology, Nagoya City University Medical School, Mizuho-ku, Nagoya, Japan; and ykito@cc.saga-u.ac.jp.
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Kito
authors.affiliation: Department of Cell Physiology, Nagoya City University Medical School, Mizuho-ku, Nagoya, Japan; and.
authors.forename: Retsu
authors.initials: R
authors.lastname: Mitsui
authors.affiliation: Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada.
authors.forename: Sean M
authors.initials: SM
authors.lastname: Ward
authors.affiliation: Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada.
authors.forename: Kenton M
authors.initials: KM
authors.lastname: Sanders
mesh_terms: D000200:Action Potentials; D000818:Animals; D005260:Female; D056885:Interstitial Cells of Cajal / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D007421:Intestine, Small / Q000166:cytology / Q000502:physiology*; D008297:Male; D008564:Membrane Potentials; D049990:Membrane Transport Modulators / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D009197:Myenteric Plexus / Q000166:cytology / Q000502:physiology*; D011817:Rabbits; D064506:Solute Carrier Family 12, Member 2 / Q000235:genetics / Q000378:metabolism; D013045:Species Specificity
chemical_list: D049990:Membrane Transport Modulators; D064506:Solute Carrier Family 12, Member 2
keywords: NKCC1; interstitial cells of Cajal; pacemaker; slow wave; small intestine