Effects of cocaine on several adrenergic system parameters

The effect of acute and chronic administration of cocaine on the sympathetic nervous system in the cardiac tissue and the adrenal glands of rats were studied. Both with acute and chronic administration of the drug, the concentration-response curve to (-)-norepinephrine on the isolated rat atria was shifted to the right, with a lower pD2. The endogenous ventricular norepinephrine levels remain unchanged after acute injections of cocaine, but when the drug was administered chronically, the endogenous neurotransmitter content were augmented about 50%. The tyrosine hydroxylase activity in atria and adrenal homogenates decreased after chronic injections of cocaine, while it was not observed any modifications in the enzyme activity after acute administrations of the drug.