Freeman L C, Muir W W
Department of Veterinary Physiology, College of Veterinary Medicine, Ohio State University, Columbus.
Anesth Analg. 1991 Jan;72(1):11-7.
Halothane effects on action potential characteristics and conduction were determined in canine Purkinje fibers, before and during alpha-adrenergic stimulation. Halothane significantly decreased effective refractory period and action potential duration in Purkinje fibers. alpha-Adrenergic stimulation restored effective refractory period and action potential duration in Purkinje fibers exposed to halothane via an alpha 1-adrenoceptor mediated effect antagonized by prazosin. Halothane significantly slowed propagation of impulses initiated at a basic cycle length of 500 ms, and conduction of premature impulses, in Purkinje fibers. In the presence of halothane, alpha-adrenergic stimulation had no additional effects on normal impulse propagation; however, alpha-adrenergic stimulation significantly slowed the conduction of premature impulses in Purkinje fibers exposed to halothane. These data refute a previous report that alpha-adrenergic stimulation enhances halothane's negative dromotropic effect in Purkinje fibers paced at a basic drive cycle length. alpha-Adrenergic prolongation of the conduction times of premature stimuli in Purkinje fibers exposed to halothane is a new finding.
在犬浦肯野纤维中，于α-肾上腺素能刺激之前及期间，测定了氟烷对动作电位特征和传导的影响。氟烷显著缩短了浦肯野纤维的有效不应期和动作电位时程。α-肾上腺素能刺激通过哌唑嗪拮抗的α1-肾上腺素能受体介导效应，恢复了暴露于氟烷的浦肯野纤维的有效不应期和动作电位时程。氟烷显著减慢了在500毫秒基础周期长度起始的冲动在浦肯野纤维中的传播，以及早搏冲动的传导。在有氟烷存在的情况下，α-肾上腺素能刺激对正常冲动传播无额外影响；然而，α-肾上腺素能刺激显著减慢了暴露于氟烷的浦肯野纤维中早搏冲动的传导。这些数据驳斥了之前的一份报告，该报告称α-肾上腺素能刺激会增强在基础驱动周期长度起搏的浦肯野纤维中氟烷的负性变传导效应。α-肾上腺素能延长暴露于氟烷的浦肯野纤维中早搏刺激的传导时间是一项新发现。
