Selective beta 1 and beta 2 adrenoceptor blockade on epinephrine-induced arrhythmias in halothane anaesthetized dogs.
Beta 2 as well as beta 1 adrenoceptors have been recognized in the heart of vertebrates. They mediate a positive chronotropic action of catecholamines. We compared the effect of selective beta 1 and beta 2 adrenoceptor antagonists on the genesis of halothane-epinephrine arrhythmias in dogs. The arrhythmogenic dose (AD) of epinephrine was increased in the presence of l-metoprolol, a selective beta 1 antagonist (8.40 +/- 1.13 micrograms.kg-1 x min-1; mean +/- SEM), compared with control value (2.62 +/- 0.56) (P < 0.05). In contrast, ICI-118,551, a selective beta 2 antagonist, did not change the AD (2.36 +/- 0.43). Adding ICI-118,551 to l-metoprolol did not affect the AD of epinephrine in the presence of l-metoprolol alone (6.34 +/- 0.74 vs 8.40 +/- 1.13). These results suggest that selective beta 1 blockade is effective in preventing halothane-epinephrine arrhythmias, but selective beta 2 blockade is not.
Hayashi
Y
Y
Department of Anesthesiology, National Cardiovascular Center, Osaka, Japan.
Sumikawa
K
K
Kamibayashi
T
T
Yamatodani
A
A
Mammoto
T
T
Kuro
M
M
Yoshiya
I
I
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000139:chemically induced* / Q000503:physiopathology / Q000517:prevention & control; D001794:Blood Pressure / Q000187:drug effects; D005117:Cardiac Complexes, Premature / Q000139:chemically induced / Q000503:physiopathology / Q000517:prevention & control; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000008:administration & dosage / Q000009:adverse effects*; D005260:Female; D006221:Halothane / Q000008:administration & dosage / Q000009:adverse effects*; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D008790:Metoprolol / Q000008:administration & dosage / Q000494:pharmacology*; D011412:Propanolamines / Q000008:administration & dosage / Q000494:pharmacology*
D000319:Adrenergic beta-Antagonists; D011412:Propanolamines; C026777:ICI 118551; D008790:Metoprolol; D006221:Halothane; D004837:Epinephrine