[Study of maximal response of the rat vas deferens. I - study of adrenergic amines with diverse mechanisms of action and the influence of cast concentration in the physiological solution].

As a preliminary to research on phenomena connected with the appearance of maximal responses in the isolated rat vas deferens greater than those obtainable with noradrenaline, the responses to noradrenaline, octopamine and thyramine under various experimental conditions are discussed. Octopamine give maximal responses which are consistently greater than those with noradrenaline but the differences are scarcely significant. Variation of the Ca2+ concentration in the physiological solution affects response to the three amines in a different way. It appears that when there is an indirect component in the mechanism of action, lack of Ca2+ has less effect on the activity of the compound.