L-Type Ca'2+' Channels in the Enteric Nervous System Mediate Oscillatory Cl'-' Secretion in Guinea Pig Colon
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Accession number;07A0139143
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| Title;L-Type Ca'2+' Channels in the Enteric Nervous System Mediate Oscillatory Cl'-' Secretion in Guinea Pig Colon |
| Author;
NISHIKITANI MARIKO
(Department of Physiology, Kitasato University School of Medicine)
YASUOKA YUKIKO
(Department of Physiology, Kitasato University School of Medicine)
KAWADA HIDEAKI
(Department of Physiology, Kitasato University School of Medicine)
KAWAHARA KATSUMASA
(Department of Physiology, Kitasato University School of Medicine)
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Journal Title;Tohoku J Exp Med
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Journal Code:G0649A
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ISSN:0040-8727
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VOL.211;NO.2;PAGE.151-160 (J-STAGE)(2007)
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| Figure&Table&Reference;FIG.7, REF.36 |
| Pub. Country;Japan |
| Language;English |
| Abstract;The enteric nervous system regulates epithelial ion and fluid secretion. Our previous study has shown that the low (0.2-1 mM) concentrations of Ba'2+', a K'+' channel inhibitor, evoke Ca'2+'-dependent oscillatory Cl- secretion via activation of submucosal cholinergic neurons in guinea pig distal colon. However, it is still unclear which types of Ca'2+' channels are involved in the oscillation at the neuroepithelial junction. We investigated the inhibitory effects of organic and inorganic Ca'2+' channel antagonists on the short circuit current (Isc) of colonic epithelia (mucosa-submucosa sheets) mounted in Ussing chambers. The amplitude (412 .+-. 37 .MU.A cm'-2') and frequency (2.6 .+-. 0.1 cycles min'-1') of the Ba'2+'-induced Isc in normal (1.8 mM) Ca'2+' solution (n = 26) significantly decreased by 37.6% and 38.5%, respectively, in the low (0.1 mM) Ca'2+' solution (n = 14). The Isc amplitude was reversibly inhibited by either verapamil (an L-type Ca'2+' channel antagonist) or divalent cations (Cd'2+', Mn'2+', Ni'2+') in a concentration-dependent manner. The concentration of verapamil for half-maximum inhibition (IC50) was 4 and 2 .MU.M in normal and low Ca'2+' solution, respectively. The relative blocking potencies of metal ions were Cd'2+' > Mn'2+', Ni'2+' in normal Ca'2+' solution. In contrast, the frequency of Isc was unchanged over the range of concentrations of the Ca'2+' channel antagonists used. Our results show that the oscillatory Isc evoked by Ba'2+' involves L-type voltage-gated Ca'2+' channels. We conclude that L-type Ca'2+' channels play a key role in the oscillation at the neuroepithelial junctions of guinea pig colon. (Author abst.) |
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