Abstract
The vascular effect of tetrodotoxin has been studied in innervated pump-perfused cat's hind leg preparations in which the blood came either from the same animal, or, via cross-perfusion, from a donor animal. In doses of 0.5 to 2.0 µg/kg i.v., systemic hypotension produced by tetrodotoxin was invariably accompanied by a reflex vasoconstriction in the perfused leg. Such reflex activity can occur even when the maximal vasoconstrictor response elicited by electrical stimulation of the lumbar sympathetic nerve was depressed. Intra-arterial injection of tetrodotoxin into the perfused leg produced vasodilation even in preparations in which complete blockade of adrenergic nerve terminalR and alpha and beta receptors had been secured. Higher doses of tetrodotoxin (3.0 and 4.0 µg/kg) prevented reflex vasoconstriction. The results show that a tetrodotoxin hypotension has a direct component in relaxing. vascular smooth muscle produced at low doses and an indirect component of releasing vasomotor tone produced additionally at higher doses.
Footnotes
- Received November 23, 1970.
- Accepted March 19, 1971.
- © 1971, by The Williams & Wilkins Company
JPET articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|
