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) 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 Zhang, Y. Articles by Paterson, W. G. Search for Related Content PubMed PubMed Citation Articles by Zhang, Y. Articles by Paterson, W. G.

Nitric oxide contracts longitudinal smooth muscle of opossum oesophagus via excitation-contraction coupling

Yong Zhang and William G. Paterson

1. The effects of sodium nitroprusside (SNP) and diethylenetriamine/nitric oxide adduct (DETA/NO), putative nitric oxide (NO) donors, on opossum oesophageal longitudinal smooth muscle were investigated using isometric tension and intracellular micro-electrode recordings.
2. SNP produced concentration-dependent contractions of oesophageal longitudinal smooth muscle with an EC₅₀ of 239.6 ± 78.2 µM (mean ± S.E.M., n = 10). Maximal contraction induced by SNP (1 mM) was about 75.5 ± 8.5 % (n = 10) of the 60 mM KCl-induced contraction. The SNP-induced contraction was resistant to tetrodotoxin (TTX; 1 µM), but abolished by nifedipine (1 µM), as well as by niflumic acid (300 µM) and 9-anthroic acid (9-AC; 1 mM), Ca²⁺-activated Cl^- channel blockers.
3. DETA/NO at concentrations of 100 and 500 µM induced 83.1 ± 24.4 and 104.1 ± 34.9 % of the 60 mM KCl-induced contraction (n = 4), respectively, which was abolished by nifedipine (1 µM), niflumic acid (300 µM) and 9-AC (1 mM).
4. Pre-application of 1H-[1,2,4]oxidiazolo[4,3,-]quinoxalin-1-one (ODQ) (10 µM), a guanylate cyclase inhibitor, significantly inhibited the SNP-induced contraction, whereas 8-bromo-cGMP (1 mM), a membrane-permeable analogue of cGMP, mimicked the SNP-induced contraction.
5. Intracellular recordings revealed that SNP (300 µM) depolarized resting membrane potentials (RMPs) and increased the frequency of spontaneous spike-like action potentials. However, these electrical alterations were eliminated by pretreatment with niflumic acid (300 µM).
6. These results suggest that NO produces an excitation-contraction coupling in opossum oesophageal longitudinal smooth muscle via a cGMP-dependent signalling pathway. This contraction depends on extracellular Ca²⁺ entry through activation of L-type Ca²⁺ channels.

This article has been cited by other articles:

				R. K. Campbell, R. W. Wells, D. V. Miller, and W. G. Paterson Role of cADPR in sodium nitroprusside-induced opossum esophageal longitudinal smooth muscle contraction Am J Physiol Gastrointest Liver Physiol, June 1, 2007; 292(6): G1543 - G1548. [Abstract] [Full Text] [PDF]

				Y. Zhang and W. G Paterson Excitatory purinergic neurotransmission in smooth muscle of guniea-pig taenia caeci J. Physiol., March 15, 2005; 563(3): 855 - 865. [Abstract] [Full Text] [PDF]