Some differences in the effects of different sympathomimetic amines on the isolated innervated rat diaphragm preparation.

Abstract

WHEN the electrically stimulated contractions of the isolated innervated rat diaphragm preparation are depressed by extra potassium chloride in Krebs solution, addition of adrenaline produces recovery1,2. Further, when mixtures of adrenaline and potassium chloride are added to preparations already depressed by extra potassium, 0.2 µgm. adrenaline antagonizes as much as 5 mgm. of the chloride2. The approximate amounts of twelve different sympathomimetic amines needed to antagonize in this way 5 mgm. potassium chloride have now been found ; they are shown, relative to adrenaline as unity, in Table 1, together with the formulae of the amines.