Abstract
Endothelium-denuded strips of rabbit thoracic aorta relax on exposure to light. This response is similar to endothelium-dependent relaxation as it is inhibited by hemoglobin and methylene blue, and is mediated by an increase in cyclic GMP. We now demonstrate that photorelaxation decreases on repeated exposure to light. The response can be restored by treating the depleted smooth muscle strips with acidified nitrite, but not nitrite alone, and with the nitric oxide donors, S-nitrosopenicillamine and glyceryl trinitrate, but not with hydralazine. These data indicate that photorelaxation is mediated in part by a "pool" of light-activated vasodilator(s) and suggest that this may act as a store of nitric oxide which could play a role in the regulation of vascular tone.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Aorta, Thoracic / drug effects
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Aorta, Thoracic / physiology
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Aorta, Thoracic / radiation effects
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Endothelium, Vascular / drug effects
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Endothelium, Vascular / physiology
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In Vitro Techniques
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Light*
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Male
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Muscle Contraction / drug effects
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Muscle Contraction / physiology
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Muscle Relaxation / drug effects
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Muscle Relaxation / physiology
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Muscle Relaxation / radiation effects
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Muscle, Smooth, Vascular / drug effects
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Muscle, Smooth, Vascular / physiology*
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Muscle, Smooth, Vascular / radiation effects*
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Nitric Oxide / metabolism
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Nitric Oxide / pharmacology*
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Nitroglycerin / metabolism
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Nitroglycerin / pharmacology
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Phenylephrine / pharmacology
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Photochemistry
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Rabbits
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Sodium Nitrite / pharmacology
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Vasodilation / physiology
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Vasodilation / radiation effects*
Substances
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Phenylephrine
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Nitric Oxide
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Nitroglycerin
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Sodium Nitrite