title: [Dynamic changes in depolarization of action potentials by high frequency stimulation in guinea pig papillary muscles].
abstract: The effect of high frequency stimulation on rate-dependent depression of depolarization of action potentials was studied with computer and standard microelectrode techniques in guinea pig papillary muscles. After increasing driving frequency from 0.5 to 6 Hz, decreases in Vmax, APA and OS were found. Changes of upstroke velocity during phase 0 between driving frequency 6 and 0.5 Hz could be described as a parabola. The rate-dependent depression of depolarization was exaggerated by tetrodotoxin (TTX), particularly during the accelerating period of phase 0. A progressive decline in Vmax, which could be fitted by a power function curve, was observed after changing driving frequency from 1 to 5 Hz. TTX significantly influenced the decline in Vmax and the regression coefficients in fitted equations.
authors.forename: W Q
authors.initials: WQ
authors.lastname: Shen
authors.forename: X Y
authors.initials: XY
authors.lastname: Xu
authors.forename: W W
authors.initials: WW
authors.lastname: Zhao
authors.forename: Z X
authors.initials: ZX
authors.lastname: Duan-Mu
authors.forename: Z M
authors.initials: ZM
authors.lastname: Yu
authors.forename: X M
authors.initials: XM
authors.lastname: Yu
authors.forename: L Y
authors.initials: LY
authors.lastname: Wang
authors.forename: L Y
authors.initials: LY
authors.lastname: Zhang
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D004558:Electric Stimulation; D005260:Female; D006168:Guinea Pigs; D008297:Male; D008839:Microelectrodes; D010210:Papillary Muscles / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D013779:Tetrodotoxin