RT Journal Article SR Electronic T1 CONCERNING A POSSIBLE ACTION OF GUANETHIDINE (SU-5864) IN SMOOTH MUSCLE JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 24 OP 30 VO 129 IS 1 A1 R. A. Maxwell A1 A. J. Plummer A1 H. Povalski A1 F. Schneider YR 1960 UL http://jpet.aspetjournals.org/content/129/1/24.abstract AB Guanethidine (Su-5864) alters the response to a series of pressor phenylalkylamines such that the amines can be placed in three categories: 1) augmented or not suppressed are the amines with m- and p-hydroxylation or m- or p-hydroxylation plus hydroxylation on the carbon adjacent to the ring, i.e., the beta carbon; 2) reversibly blocked are the amines with beta hydroxylation only; and 3) irreversibly blocked are the amines with no or only p-hydroxylation. Su-5864 negates the blockade of norepinephrine produced by the "surmountable" adrenergic blocking agent phentolamine but will not negate the blocking action of the "unsurmountable" blocking agent Dibenamine. Following Su-5864 administration the acutely denervated nictitating membrane of the cat is retracted equally or more than is the chronically denervated nictitating membrane. The significance of these data are discussed and an argument presented in favor of an action of Su-5864 in smooth muscle.