Abstract
In rat aortic rings, hydroxocobalamin (10-30 microM) produced concentration-dependent reductions of the relaxant action of nitric oxide (NO) and the endothelium-dependent, NO-mediated, relaxant action of acetylcholine. In anococcygeus muscles, hydroxocobalamin (10-30 microM) reduced but also prolonged, NO-induced relaxations, but had no effect on non-adrenergic, non-cholinergic-mediated relaxations. Hydroxocobalamin had no effect on the NO-independent relaxant action of papaverine in either tissue. It is suggested that hydroxocobalamin sequesters NO by forming nitrosocobalamin. Nitrosocobalamin did not relax aortic rings, but produced a slowly developing and prolonged relaxation of anococcygeus muscles.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Acetylcholine / pharmacology
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Animals
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Aorta, Thoracic / drug effects
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Autonomic Nervous System / physiology
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Endothelium, Vascular / physiology
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Hydroxocobalamin / analogs & derivatives
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Hydroxocobalamin / pharmacology*
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In Vitro Techniques
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Male
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Muscle Relaxation / drug effects
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Muscle, Smooth / drug effects*
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Muscle, Smooth / innervation
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Muscle, Smooth / physiology
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Muscle, Smooth, Vascular / drug effects*
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Muscle, Smooth, Vascular / physiology
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Nitric Oxide / metabolism
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Nitric Oxide / pharmacology*
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Nitroso Compounds / pharmacology
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Papaverine / pharmacology
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Rats
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Rats, Sprague-Dawley
Substances
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Nitroso Compounds
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nitrosocobalamin
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Nitric Oxide
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Papaverine
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Acetylcholine
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Hydroxocobalamin