Abstract
Methoxamine showed positive inotropic and chronotropic actions in the rat atria. These actions were blocked by phentolamine, but not by propranolol. PTU treatment sensitized the animals to the positive inotropic and chronotropic actions of methoxamine. These results verify the findings of previous research that there are α adrenergic receptors in rat atria, that stimulation of these receptors shows positive inotropic and chronotropic action and that a receptors are sensitized by PTU treatment.
