Requirement for endothelium‐derived nitric oxide in vasodilatation produced by stimulation of cholinergic nerves in rat hindquarters

1 We aimed to determine whether nitric oxide (NO) and/or the endothelium is involved in cholinergic neurogenic vasodilatation in the rat isolated hindquarters. 2 The abdominal aorta was cannulated for perfusion of the rat hindquarters with Krebs bicarbonate solution containing phenylephrine, to indu...

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Published in:British journal of pharmacology 1994-06, Vol.112 (2), p.630-634
Main Authors: Loke, K.E., Sobey, C.G., Dusting, G.J., Woodman, O.L.
Format: Article
Language:English
Subjects:
3‐3 cholamidopropyl dimethylammonio 1‐propanesulphonate (CHAPS)
Acetylcholine
Biological and medical sciences
Blood vessels and receptors
cholinergic neurogenic dilatation
endothelium
Fundamental and applied biological sciences. Psychology
NG‐nitro‐l‐arginine
nitric oxide
Vertebrates: cardiovascular system
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Summary:1 We aimed to determine whether nitric oxide (NO) and/or the endothelium is involved in cholinergic neurogenic vasodilatation in the rat isolated hindquarters. 2 The abdominal aorta was cannulated for perfusion of the rat hindquarters with Krebs bicarbonate solution containing phenylephrine, to induce basal constrictor tone. In the presence of noradrenergic neurone blockade with guanethidine (200 mg kg−1, i.p.) electrical stimulation of peri‐aortic nerves induced frequency‐dependent decreases in hindquarters perfusion pressure, indicating vasodilatation. Both the endothelium‐dependent vasodilator, acetylcholine (ACh) and the endothelium‐independent vasodilator, sodium nitroprusside (SNP) induced dose‐dependent decreases in perfusion pressure. In each experiment, responses to either nerve stimulation, ACh or SNP were recorded before and after treatment with saline vehicle, atropine (1 μm), NG‐nitro‐l‐arginine (l‐NOARG, 100 μm), l‐arginine (1 mm), l‐arginine plus l‐NOARG, or 3–3 cholamidopropyl dimethylammonio 1‐propanesulphonate (CHAPS, 30 mg). Hindquarters dilatation after each treatment was expressed as a percentage of the control response. 3 Following treatment with saline, responses to nerve stimulation and ACh were 99 ± 9% and 107 ± 10% of control, respectively demonstrating the reproducibility of these responses. Nerve stimulation‐induced dilatation was abolished by atropine (0 ± 0% of control, P < 0.05) or reduced to 14 ± 10% of control by NO synthase inhibition with l‐NOARG (P < 0.05). Dilator responses to ACh were also abolished by atropine (0 ± 0% of control, P < 0.05) or inhibited by l‐NOARG (59 ± 10% of control, P < 0.05), indicating that the neurogenic dilatation is cholinergic and is mediated by NO. The administration of the NO precursor, l‐arginine, prevented the inhibitory effect of l‐NOARG on dilator responses to nerve stimulation and ACh (l‐arginine plus l‐NOARG: 89 ± 13% and 122 ± 24% of control, respectively). In addition CHAPS, which removes endothelial cells, inhibited responses to both nerve stimulation (0 ± 0% of control, P < 0.05) and ACh (33 ± 8% of control, P
ISSN:0007-1188
1476-5381
DOI:10.1111/j.1476-5381.1994.tb13121.x