Effect of adrenergic agonists on phosphatidylinositol labelling in heart and aorta

(1) The metabolism of phosphatidylinositol has been investigated in heart fragments and aorta slices incubated with adrenergic agonists. (2) Noradrenaline and isoprenaline had no stimulatory effect on 32Pi incorporation into phosphatidylinositol in cat and guinea-pig hearts. (3) Incorporation of 32Pi into phosphatidylinositol was enhanced by noradrenaline and methoxamine in cat aorta. (4) This information is consistent with the idea that the enhanced phosphatidylinositol turnover produced during adrenergic stimulation is mediated through alpha-adrenergic receptors and not through beta-adrenoceptors.