The Modes of Action of Gallamine

摘要: The action of gallamine, a classical competitive neuromuscular blocking agent, has been examined on voltage-clamped endplates frog skeletal muscle fibres. Gallamine produces parallel shift the equilibrium log (concentration)--response curves in concentrations up to about 40 $\mu $M. At membrane potential -- 70 m V Schild plot dose ratios so measured gradient slightly less than theoretical value, for antagonist, unity. apparent constant `competitive' block is 2 $M, and approximately independent potential. Fluctuation analysis endplate current shows two components presence gallamine. results can be fitted, over range tested, by mechanism that involves open ion channels gallamine manner similar procaine or quaternary local anaesthetic analogues. rate constants this are strongly dependent 100 association 4 $\times $ 10$^{7}$ M$^{-1}$ s$^{-1}$, dissociation 600 15 Other kinetic measurements (voltage-jump relaxation, nerve-evoked currents) give consistent with conclusion, but apparently these valid conditions narrower fluctuation analysis.