[Dynamic changes in depolarization of action potentials by high frequency stimulation in guinea pig papillary muscles].
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.
Shen
W Q
WQ
Xu
X Y
XY
Zhao
W W
WW
Duan-Mu
Z X
ZX
Yu
Z M
ZM
Yu
X M
XM
Wang
L Y
LY
Zhang
L Y
LY
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
D013779:Tetrodotoxin