title: Effects of piperazine derivatives on the activity of frog skeletal muscle fibers.
abstract: 1. This study was undertaken to characterize the effects of some piperazine derivatives on excitable cell membranes. Three original Bulgarian compounds with favorable effects on cardiovascular and nervous system--piperazine derivatives with code names P-11 (N1-[3-oxo-3-phenyl-2-methyl-propyl]-N4-[trans-3-hydroxy-1,2,3,4- tetrahydro-2-naphthyl]-piperazine dihydrochloride), AS2 (N1-benzhydryl-N4-allyl piperazine dihydrochloride) and 35-M (Schiff's base of N1-benzhydryl-N4-aminopiperazine with triacetonamine, dioxalate salt) were tested in experiments with conventional microelectrode technique on isolated frog muscle fibers. 2. After 30-min treatment with tested drugs at concentrations of 10-100 microM the recorded intra-(ICAP) and extracellular action potentials (ECAPs) showed an amplitude decrease and duration increase. The total ionic current (Ii) decreased as the outward phase was almost abolished by P-11. The propagation velocity (PV) of excitation and the twitch amplitude also decreased. These changes were agent- and concentration-dependent. 3. The effect potency of the agents diminished in the following order: P-11 > AS2 > 35-M. 4. Concentrations higher than 100 microM for all agents completely, but reversibly, inhibited membrane excitability. 5. The results demonstrate compound- and concentration-induced modulation of Ca2+ current with blockade of Ca(2+)-dependent K+ and Cl- membrane channels of muscle fiber treated with the compound tested.
authors.affiliation: Institute of Biophysics, Bulgarian Academy of Sciences, Sofia, Bulgaria.
authors.forename: N
authors.initials: N
authors.lastname: Radicheva
authors.forename: M
authors.initials: M
authors.lastname: Vydevska
authors.forename: K
authors.initials: K
authors.lastname: Mileva
mesh_terms: D000200:Action Potentials / Q000187:drug effects*; D000818:Animals; D000969:Antinematodal Agents / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D018482:Muscle, Skeletal / Q000187:drug effects*; D000077489:Piperazine; D010879:Piperazines / Q000494:pharmacology*; D011893:Rana esculenta
chemical_list: D000969:Antinematodal Agents; D010879:Piperazines; D000077489:Piperazine