Effects of RO 5-4864 and PK 11195 on guinea pig trachea.
Previous reports have suggested a role played by peripheral benzodiazepine receptors (PBZ) in the regulation of calcium. The aid of this investigation was to evaluate the effects of Ro 5-4864 (PBZ agonist) and PK11195 (PBZ antagonist) in guinea pig trachea and their possible role in the regulation of calcium. Ro 5-4864 and PK 11195 showed spasmolytic effects on the contraction curve induced by acetylcholine. Moreover, Ro 5-4864, PK 11195 and diltiazem (a Ca2+ -antagonistic drug) shifted to the right the contraction curves induced by acetylcholine, potassium chloride (KCl), calcium chloride (CaCl2), or by Bay K 8644. These results demonstrate that the benzodiazepines and their antagonists may exhibit Ca2+ -antagonistic activity. Ro 5-4864 and PK 11195 may exert this effect at a site that is a component of, or is associated with, voltage operated calcium channels (VOC).
Matera
M G
MG
Institute of Pharmacology and Toxicology, Faculty of Medicine and Surgery-2nd University of Naples, Italy.
Costantino
M
M
D'agostino
B
B
Marabese
I
I
Lucarelli
C
C
Rossi
F
F
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001570:Benzodiazepinones / Q000494:pharmacology*; D003292:Convulsants / Q000494:pharmacology*; D004110:Diltiazem / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D007546:Isoquinolines / Q000494:pharmacology*; D009126:Muscle Relaxation; D011963:Receptors, GABA-A / Q000187:drug effects*; D014132:Trachea / Q000187:drug effects*
D001570:Benzodiazepinones; D003292:Convulsants; D007546:Isoquinolines; D011963:Receptors, GABA-A; C028513:4'-chlorodiazepam; D004110:Diltiazem; D000109:Acetylcholine; C037850:PK 11195