Abstract
It has been suggested that the endothelin (ET) ETB receptor could mediate endothelium-dependent vasodilation to ET-1 or ET-3, but its in vivo role is still largely unknown. We used sarafotoxin S6C, a selective agonist of the ETB receptor, to study the in vivo effects of ETB stimulation. SRTX S6C induced a transient decrease in blood pressure, followed by a long-lasting pressor response accompanied by a marked renal and mesenteric vasoconstriction. No constriction was observed in isolated mesenteric arteries in vitro, indicating that the in vivo vasoconstrictor effect is most likely indirect. The pressor effect of SRTX S6C was not dependent on central stimulation of ETB receptors and was not mediated by catecholamines from the adrenal medulla, prostanoids or ET-1.
MeSH terms
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Animals
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Blood Pressure / drug effects
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Decerebrate State
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Endothelins / pharmacology*
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Endothelium, Vascular / physiology
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Heart Rate / drug effects
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In Vitro Techniques
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Male
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Mesenteric Arteries / drug effects
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Mesenteric Arteries / physiology*
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Methoxamine / pharmacology
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Muscle, Smooth, Vascular / drug effects
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Muscle, Smooth, Vascular / physiology*
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Rats
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Rats, Inbred Strains
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Receptors, Cell Surface / drug effects
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Receptors, Cell Surface / physiology*
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Receptors, Endothelin
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Regional Blood Flow / drug effects
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Renal Circulation / drug effects
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Vasoconstriction* / drug effects
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Vasoconstrictor Agents / pharmacology*
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Vasodilation* / drug effects
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Viper Venoms / pharmacology*
Substances
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Endothelins
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Receptors, Cell Surface
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Receptors, Endothelin
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Vasoconstrictor Agents
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Viper Venoms
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sarafotoxins s6
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Methoxamine