Journal Article

Response of coronary microvascular collaterals to activation of ATP-sensitive K+ channels

Kathryn G Lamping, Daniel W Nuno, Leonard A Brooks and Mikio Fujii

in Cardiovascular Research

Published on behalf of European Society of Cardiology

Volume 35, issue 2, pages 377-383
Published in print August 1997 | ISSN: 0008-6363
Published online August 1997 | e-ISSN: 1755-3245 | DOI: https://dx.doi.org/10.1016/S0008-6363(97)00112-0
Response of coronary microvascular collaterals to activation of ATP-sensitive K+ channels

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Abstract

Objective: Studies have suggested that collateral vessels of the coronary and hind-limb circulations are more sensitive to activation of ATP-sensitive K+ channels than are non-collateral vessels. The objective of the present study was to compare responses of microvascular non-collaterals, native collaterals and stimulated collaterals in the heart to three vasodilators which act through different mechanisms: activation of ATP-sensitive K+ channels with aprikalim, release of nitric oxide with acetylcholine, and endothelium-independent activation of soluble guanylate cyclase with nitroglycerin. Methods: Collateral growth was stimulated by placing an Ameroid occluder on the proximal left circumflex artery in dogs. Non-collaterals, native collaterals and stimulated collaterals (100–220 μm in diameter) were isolated, cannulated on micropipettes and pressurized in vitro. Vessel diameters were measured using videomicroscopy. Results: Dilation to aprikalim (10−8–10−5 M), acetylcholine (10−9–10−6 M) and nitroglycerin (10−8–3×10−4 M) were similar in non-collateral, native collateral and stimulated collaterals. Dilation of native collaterals to aprikalim and acetylcholine was attenuated by glibenclamide (10 μM), an inhibitor of ATP-sensitive K+ channels, but not by tetraethylammonium (1 mM), a non-selective inhibitor of K+ channels. Dilation of native collaterals to acetylcholine but not aprikalim was also inhibited by nitro-l-arginine (10 μM), an inhibitor of nitric oxide synthase. Conclusion: These findings suggest that microvascular native and stimulated collaterals respond to activation of ATP-sensitive K+ channels and acetylcholine similar to non-collaterals of similar size. Thus, changes in reactivity of collaterals to activation of ATP-sensitive K+ channels are not related to changes in the ability of the vessels to respond to vasodilators but may primarily be determined by a change in the distribution of collateral vessel size.

Keywords: Aprikalim; Tetraethylammonium; Acetylcholine; Nitric oxide; Nitroglycerin; Potassium channel opener; Potassium channel, ATP sensitive; Dog, arteries; Collateral circulation

Journal Article.  4262 words.  Illustrated.

Subjects: Cardiovascular Medicine

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