Conditions permitting suppression of stretch-induced and vasoconstrictor tone by basal nitric oxide activity in porcine cerebral artery
| Autor: | Wallis, Sarah J, Martin, William |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2000 |
| Předmět: |
Male
Serotonin Swine Cerebral Arteries In Vitro Techniques Nitric Oxide Muscle Smooth Vascular NG-Nitroarginine Methyl Ester Vasoconstriction 15-Hydroxy-11 alpha 9 alpha-(epoxymethano)prosta-5 13-dienoic Acid Muscle Tonus Papers cardiovascular system Animals Female Endothelium Vascular Enzyme Inhibitors Nitric Oxide Synthase Muscle Contraction |
| Popis: | This study examined the ability of basal nitric oxide activity to suppress intrinsic and vasoconstrictor tone in isolated rings of porcine cerebral artery. Following stretch of approximately 1 g, N(G)-nitro-L-arginine methyl ester (L-NAME, 100 microM) produced a rise in tone in endothelium-containing but not endothelium-denuded rings. Thus, intrinsic tone was present and was powerfully suppressed by basal nitric oxide activity. Nevertheless, when concentration-response curves were constructed to U46619 and 5-hydroxytryptamine (5-HT), no endothelium-dependent depression of vasoconstriction was observed. It therefore appeared that basal nitric oxide activity was able to suppress intrinsic but not vasoconstrictor tone in these vessels. Stretch-tension curves generated following the application of stretch over the range 0 - 5. 5 g on endothelium-denuded rings showed that tension was stretch-induced. Experiments conducted in the presence of L-NAME (100 microM) revealed that the level of tone present in endothelium-containing rings was substantially higher than in endothelium-denuded rings across the entire range of stretch. When endothelium-containing and endothelium-denuded rings were set at similar levels of stretch-induced tone, rather than similar levels of stretch, the presence of the endothelium now depressed significantly vasoconstrictor responses to U46619 and 5-HT. Thus, when endothelium-containing and endothelium-denuded rings of porcine cerebral artery are set at similar points along their respective stretch-tension curves, rather than at similar levels of stretch, basal nitric oxide activity can be seen to inhibit both stretch-induced and vasoconstrictor tone. |
| Databáze: | OpenAIRE |
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