EFFECT OF AMPHETAMINE ON THE SYNAPTIC TRANSMISSION OF SYMPATHETIC GANGLIA AND SPINAL CORD

¹ Department of Pharmacology and Biochemistry, Catholic University of Chile, Santiago, Chile

The effect of amphetamine on the synaptic transmission of the sympathetic ganglion was studied in cats anesthetized with Nembutal and in decerebrate cats. Amphetamine has a potentiating effect on the response of the sympathetic ganglion when small doses are used but a depressor effect when given in high doses. Amphetamine does not evidence tachyphylaxis in the ganglion and does not produce direct response of the ganglion or repetitive response to electric stimulation of the preganglionic fibers.

The effect of amphetamine on the spinal reflex was studied in cats anesthetized with Dial and in decerebrate cats. With submaximal or maximal stimuli a small dose of amphetamine produces a potentiation and a large dose a depression of the monosynaptic response. The normal response of the spinal cord varies according to the frequency of the stimuli. Above ten per second the response falls sharply. The drug does not alter the frequency at which this change takes place.

In cats in which barbiturate was used, the dose of amphetamine required to obtain the same effect was two to four times larger than that needed in decerebrate cats; this demonstrates the antagonism of amphetamine and barbiturates.