4-Hydroxy-2-methyl-4-phenyl-1,2,3,4-tetrahydroisoquinoline (PI-OH): a new potentiator of sympathomimetic amines on the rat anococcygeus muscle.
1. The potentiating effects of racemic 4-hydroxy-2-methyl-4-phenyl-1,2,3,4-tetrahydroisoquinoline (PI-OH), cocaine, desipramine and nomifensine on the concentration-response curves of the rat anococcygeus muscle to noradrenaline (NA) and field stimulation were examined. 2. PI-OH and cocaine concentration-dependently potentiated the responses of anococcygeus muscle to NA and field stimulation, but the activity of PI-OH was stronger than that of cocaine on both responses. 3. At high concentrations the potentiating activities of desipramine and nomifensine were less, a fact that was explained by their postsynaptic inhibitory properties; the actions of nomifensine and desipramine as antagonists against NA were competitive and non-competitive, respectively. 4. It is concluded that PI-OH may be an ideal potentiator of the response to NA in adrenergically-innervated tissues because it has no side effects such as postsynaptic inhibition.
Ishida
Y
Y
Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, University of Tokushima, Japan.
Koga
N
N
Nanbu
T
T
Kihara
M
M
Kobayashi
S
S
D000818:Animals; D003042:Cocaine / Q000494:pharmacology; D003891:Desipramine / Q000494:pharmacology; D004357:Drug Synergism; D004558:Electric Stimulation; D066298:In Vitro Techniques; D008297:Male; D009132:Muscles / Q000187:drug effects* / Q000502:physiology; D009627:Nomifensine / Q000031:analogs & derivatives* / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013566:Sympathomimetics / Q000494:pharmacology*
D013566:Sympathomimetics; C056761:4-hydroxy-2-methyl-4-phenyl-1,2,3,4-tetrahydroisoquinoline; D009627:Nomifensine; D011433:Propranolol; D003042:Cocaine; D003891:Desipramine