ISSN:
1474-8673
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Chemistry and Pharmacology
,
Medicine
Notes:
1 Electrical field stimulation (EFS) (0.5 ms in train of 2–32 Hz for 300 ms) in smooth muscle of pigeon oesophagus, in the presence of atropine (1 μm) and guanethidine (1 μm), elicited an inhibitory response consisting of a transient hyperpolarization (inhibitory junction potential, IJP) associated with muscle relaxation. 2 Sodium nitroprusside (SNP, 100 μm) induced hyperpolarization correlated to mechanical relaxation. 3 The nitric oxide (NO) synthase inhibitor Nω-nitro-l-arginine (from 0.1 to 100 μm) caused a concentration-dependent reduction of electromechanical response to EFS indicating a role for NO in this response. 4 Apamin (1 μm) reduced both IJP and relaxation to EFS but was without effect on the response to SNP indicating a role for purines, which are also blocked by apamin. 5 Adenosine, AMP, ADP and ATP (all from 1 μm to 1 mm) application caused transient hyperpolarization and muscular relaxation with the following order of potency: adenosine 〉 AMP 〉 ADP 〉 ATP. 6 Inhibitory responses evoked by purines are TTX (1 μm) insensitive but they were inhibited by apamin. This indicates that a purine component for the non-adrenergic non-cholinergic (NANC) response exists but the purine receptor site is not located on the neurone. 7 Overall these results suggest that NANC inhibitory response elicited by EFS presents two different components apamin-sensitive, probably purines-mediated and apamin-insensitive probably NO-mediated as apamin only partially block the response to EFS.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1474-8673.2004.00304.x
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