Abstract
1-Phenyl-4-guanylpiperazine sulfate [PGP] and its derivatives were synthesized. The effects of these compounds on blood pressure, the nictitating membrane and the action of sympathomimetic amines such as tyramine and norepinephrine were examined in spinal cats. The effects of these compounds on MAO activity were also examined using the rat liver enzyme preparation in vitro. The results obtained were briefly summarized as follows : 1) PGP derivatives caused a rise in blood pressure and a contraction of the nictitating membrane in spinal cats. 2) PGP derivatives potentiated a pressor effect and a contraction of the nictitating membrane induced by tyramine and norepinephrine in spinal cats. 3) Reserpine caused a long-lasting hypertension and contraction of the nictitating membrane in spinal cats, when the animals were pretreated with PGP. 4) PGP derivatives showed a property to inhibit monoamine oxidase (MAO) activity. 5) PGP inhibited the restoration of the pressor effect of tyramine by a slow intravenous infusion of norepinephrine.
