REVERSAL OF THE DEPRESSOR EFFECTS OF TETRAETHYL-AMMONIUM ION AND OF DIHYDROERGOTAMINE IN THE AMPHETAMINE TACHYPHYLACTIC DOG

¹ Department of Pharmacology, School of Medicine, University of Washington, Seattle 5

In anesthetized amphetamine tachyphylactic dogs, the typical depressor effects which usually follow the intravenous injection of TEA and DHE into anesthetized dogs are reversed.

On the assumption that DHE and TEA reversals arise from an inhibition of vasomotor tone in the tachyphylactic dog, the possible role of amphetamine as a ganglionic blocking agent was investigated. It is concluded that amphetamine does not block ganglionic transmission in tachyphylactic doses.

The effects of DHE and TEA on peripheral blood flow following intra-arterial injection are independent of previous intra-arterial injections of amphetamine. Femoral arterial flow is increased, whereas anterior mesenteric arterial flow is decreased by DHE, whether in the presence or the absence of previous injection of amphetamine. No appreciable changes occurred in response to TEA that did not appear to he passively related to arterial pressure fluctuation.

The mechanism of reversal of TEA and DHE blood pressure effects is not clear. Amphetamine may inhibit the vasoconstrictor center either directly or through an obscure reflex mechanism which is not dependent on arterial pressure changes.