Modification by AZ-55, Guanethidine and Bretylium of Responses of Atria and Aortic Strips to Transmural Stimulation

A new antihypertensive drug (1), l-cyclohexyl-3-guanidinoazetidine sulfate (AZ-55), structurally resembles guanethidine. It is widely known that guanethidine depresses peripheral adrenergic nerve function by preventing release ot adrenergic nerve transmitters (reviewed by Boura and Green, 2). Bretylium also possesses the adrenergic neuron blocking action, but accumulated data point to the fact that bretylium and guanethidine fail to share all mechanisms of the blocking action (2).