title: Actions of trihexyphenidyl and benztropine on squid axon membranes.
abstract: Trihexyphenidyl and benztropine have potent local anesthetic action on squid axon membranes. They suppress the peak transient sodium conductance with ED50 values equal to 1.75 X 10(-4) AND 0.78 X 10(-4) M, respectively, and shift the sodium condu-tance curve along the potential axis in the direction of depolarization by 2.3 and 8.7 mV, respectively. The time for the sodium current to attain its peak is shortened. Steady-state potassium conductance is also suppressed by these drugs and undergoes an inactivation which has a potential-dependence characteristic. The local anesthetic action combined with the anticholinergic action may warrant further study of these two drugs, especially trihexyphenidyl, as a potential antiarrhythmic agent.
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001369:Axons / Q000187:drug effects*; D001590:Benztropine / Q000494:pharmacology*; D049832:Decapodiformes / Q000502:physiology*; D066298:In Vitro Techniques; D008566:Membranes / Q000187:drug effects; D011188:Potassium / Q000502:physiology; D012964:Sodium / Q000502:physiology; D013997:Time Factors; D014282:Trihexyphenidyl / Q000494:pharmacology*; D014326:Tropanes / Q000494:pharmacology*
chemical_list: D014326:Tropanes; D001590:Benztropine; D014282:Trihexyphenidyl; D012964:Sodium; D011188:Potassium