Eperisone, an antispastic agent, possesses vasodilating actions on the guinea-pig basilar artery.
The effects of eperisone, an antispasmodic, on the electrical and mechanical properties of smooth muscle cells of the guinea-pig basilar artery were investigated. Eperisone (below 50 microM) did not modify the membrane potential, membrane resistance, excitatory junction potential evoked by perivascular nerve stimulation or the K- and 5-hydroxytryptamine-induced depolarizations. However, in concentrations over 10 microM, this agent reversibly blocked the spontaneously generated and evoked action potentials in the presence of 5 to 8 mM tetraethylammonium. The contractions evoked by high concentrations of K, 5-hydroxytryptamine or direct muscle stimulation in the presence of tetraethylammonium were dose dependently inhibited by eperisone, in concentrations over 1 microM. In Ca-free 2 mM ethylene glycol bis(beta-aminoethyl ether)-N,N'-tetraacetic acid-containing solution, 5-hydroxytryptamine produced only a single contraction. Eperisone inhibited this contraction to the same extent as that observed in the presence of Ca. These results indicate that eperisone possesses the property of a Ca antagonist on smooth muscle tissues of the guinea-pig basilar artery, in addition to the action of antispastic agent, i.e., this agent blocks the voltage-dependent influx of Ca at the smooth muscle membrane, but not at the nerve terminals, and inhibits the action of Ca in cells through inhibition of the contractile protein.
D000818:Animals; D001488:Basilar Artery / Q000187:drug effects; D002121:Calcium Channel Blockers / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D004558:Electric Stimulation; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology; D010276:Parasympatholytics / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology; D011427:Propiophenones / Q000494:pharmacology*; D012701:Serotonin / Q000494:pharmacology; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology*
D002121:Calcium Channel Blockers; D010276:Parasympatholytics; D011427:Propiophenones; D013757:Tetraethylammonium Compounds; D014665:Vasodilator Agents; C030848:eperisone; D012701:Serotonin; D004533:Egtazic Acid; D011188:Potassium