Myocardial epinephrine sensitization with subanesthetic concentrations of halothane in dogs.
The authors investigated myocardial epinephrine sensitization by subanesthetic concentrations of halothane. The dose-response relationship for the action of halothane was examined with etomidate plus varying subanesthetic concentrations of halothane in dogs. The arrhythmogenic threshold of epinephrine was decreased in a dose-dependent manner at end-tidal concentrations of halothane between 0.1 and 0.3%. At end-tidal halothane is greater than 0.3%, and no further reduction of arrhythmogenic threshold of epinephrine occurred. The plasma concentrations of epinephrine producing four or more premature ventricular contractions in 15 s were 201.3 +/- 34.3, 98.1 +/- 13.9, 60.3 +/- 8.63, 57.9 +/- 12.8, 54.5 +/- 8.61, and 53.9 +/- 4.86 ng/ml (mean +/- SEM), at 0, 0.1, 0.3, 0.5, 1.0, and 1.5% of halothane at end-tidal concentrations, respectively. The results suggest that in the presence of etomidate, halothane produces myocardial sensitization to epinephrine at subanesthetic concentrations as low as 0.1%. Increasing halothane to 0.3% produces a further reduction in the arrhythmogenic dose of epinephrine.
Hayashi
Y
Y
Department of Anesthesiology, National Cardiovascular Center, Osaka, Japan.
Sumikawa
K
K
Yamatodani
A
A
Kamibayashi
T
T
Kuro
M
M
Yoshiya
I
I
D000758:Anesthesia; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000139:chemically induced; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000494:pharmacology*; D005260:Female; D006221:Halothane / Q000008:administration & dosage / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects*; D006439:Hemodynamics / Q000187:drug effects; D008297:Male
D006221:Halothane; D004837:Epinephrine