Conditions permitting suppression of stretch‐induced and vasoconstrictor tone by basal nitric oxide activity in porcine cerebral artery

Abstract

1 This study examined the ability of basal nitric oxide activity to suppress intrinsic and vasoconstrictor tone in isolated rings of porcine cerebral artery. 2 Following stretch of approximately 1 g, N G -nitro-L-arginine methyl ester (L-NAME, 100 mM) 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. 3 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. 4 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 mM) 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. 5 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 signi®cantly vasoconstrictor responses to U46619 and 5-HT. 6 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.

Chylomicron-remnant-like particles inhibit the basal nitric oxide pathway in porcine coronary artery and aortic endothelial cells

“…Additionally, this change in tone caused by l-NOARG was only seen when the endothelium layer was intact (results not shown). N G -nitro-l-arginine methyl ester (l-NAME), another NOS inhibitor, has been reported to have a similar effect in the porcine cerebral artery [41]. These findings illustrate the importance of basal NO in maintaining the vascular tone in the coronary and cerebral circulations.…”

Interaction of prostanoid EP3 and TP receptors in guinea‐pig isolated aorta: contractile self‐synergism of 11‐deoxy‐16,16‐dimethyl PGE2

“…Second, DX‐DM PGE 2 was about 50 times more potent and had a higher maximum response than sulprostone, a potent full agonist for the EP 3 receptor (Lawrence et al ., 1992; Sharif et al ., 1998). Given that pig cerebral artery contains a contractile TP receptor system (Wallis and Martin, 2000) and other 11‐deoxy PGE and PGF analogues show considerable TP agonism (Jones et al ., 1982; Banerjee et al ., 1985), the remarkably high activity of DX‐DM PGE 2 may reflect simultaneous activation of EP 3 and TP receptors.…”

Beneficial Role of Ginseng Saponin on Hemodynamic Functions of Porcine Blood Vessel

“…The effects of GS on porcine coronary artery contraction induced by high K + , 5-HT, and acetylcholine were evaluated in an organ bath chamber. Porcine hearts were obtained from an abattoir and transferred to laboratory [21]. The left circumflex coronary (LCC) arteries were dissected and placed in PSS containing 118.3 mM NaCl, 4.7 mM KCl, 1.2 mM MgSO 4 , 1.2 mM KH 2 PO 4 , 2.5 mM CaCl 2 , 25.0 mM NaHCO 3 , 0.016 mM CaEDTA, and 11.1 mM glucose (control solution).…”