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: 90/4/577    most recent expphysiol.2004.029611v1 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 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 Google Scholar Google Scholar Articles by Chung, S.-S. Articles by Nam, T.-S. Search for Related Content PubMed PubMed Citation Articles by Chung, S.-S. Articles by Nam, T.-S. Related Collections GI & Epithelial

¹ Department of Physiology, College of Medicine, Yonsei University, Seoul 120-752, Republic of Korea ² BK 21 Project for Medical Sciences, Yonsei University, Seoul 120-752, Republic of Korea

The effect of sodium nitroprusside (SNP) on carbachol (CCh)-evoked inward cationic current (I_cat) oscillations in guinea-pig ileal longitudinal myocytes was investigated using the whole-cell patch-clamp technique and permeabilized longitudinal muscle strips. SNP (10 µM) completely inhibited I_cat oscillations evoked by 1 µM CCh. 1H-(1,2,4) Oxadiazole [4,3-a] quinoxaline-1-one (ODQ; 1 µM) almost completely prevented the inhibitory effect of SNP on I_cat oscillations. 8-Bromo-guanosine 3',5'-cyclic monophosphate (8-Br-cGMP; 30 µM) in the pipette solution completely abolished I_cat oscillations. However, a pipette solution containing Rp-8-Br-cGMP (30 µM) almost completely abolished the inhibitory effect of SNP on I_cat oscillations. When the intracellular calcium concentration ([Ca²⁺]_i) was held at a resting level using BAPTA (10 mM) and Ca²⁺ (4.6 µM) in the pipette solution, CCh (1 µM) evoked only the sustained component of I_cat without any oscillations and SNP did not affect the current. A high concentration of inositol 1,4,5-trisphosphate (IP₃; 30 µM) in the patch pipette solutions significantly reduced the inhibitory effect of SNP (10 µM) on I_cat oscillations. SNP significantly inhibited the Ca²⁺ release evoked by either CCh or IP₃ but not by caffeine in permeabilized preparations of longitudinal muscle strips. These results suggest that the inhibitory effects of SNP on I_cat oscillations are mediated, in part, by functional modulation of the IP₃ receptor, and not by the inhibition of cationic channels themselves or by muscarinic receptors in the plasma membrane. This inhibition seems to be mediated by an increased cGMP concentration in a protein kinase G-dependent manner.

(Received 9 December 2004; accepted after revision 18 March 2005; first published online 15 April 2005)
Corresponding author T.-S. Nam: Department of Physiology, College of Medicine, Yonsei University 134, Shinchon-Dong, Seodaemun-Gu, Seoul 120-752, Republic of Korea. Email: tsnam{at}yumc.yonsei.ac.kr

This article has been cited by other articles:

				G. P. Sergeant, L. Johnston, N. G. McHale, K. D. Thornbury, and M. A. Hollywood Activation of the cGMP/PKG pathway inhibits electrical activity in rabbit urethral interstitial cells of Cajal by reducing the spatial spread of Ca2+ waves J. Physiol., July 1, 2006; 574(1): 167 - 181. [Abstract] [Full Text] [PDF]