Hayashi Y, Sumikawa K, Kamibayashi T, Yamatodani A, Mammoto T, Kuro M, Yoshiya I
Department of Anesthesiology, National Cardiovascular Center, Osaka, Japan.
Can J Anaesth. 1992 Oct;39(8):873-6. doi: 10.1007/BF03008299.
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.
