苯福林对羊浦肯野纤维延迟后除极与触发活动的影响(英文)

Influences of phenylephrine on delayed afterdepolarization and triggered activity in sheep Purkinje fibers

目的:比较普萘洛尔(Pro)药物应用与否时,苯福林(Phe)对DAD与TA的不同影响.方法:绵羊浦肯野纤维细胞内微电极记录跨膜电位法.结果:Phe 1 μmol·L^(-1)灌流60 min,无Pro时,使DAD幅值由7.5±1.2增加到9.0±2.0 mV(n=8,P<0.05),DAD时程变化不显著,3/11可诱发TA;Pro 0.5 μmol·L^(-1)阻断μ受体时,前20 min使DAD幅值由7.2±1.8增加到8.3±2.1 mV(n=8,P<0.01),而后减少至6.35=1.6 mV,DAD时程从灌流前192±17延长至280±27 ms(n=8,P<0.01);同时对乙酰毒毛旋花子苷元诱发的触发活动有抑制,并可被哌唑嗪所阻断.结论:在Pro有效消除儿茶酚胺致使心律失常发生中,除阻断β受体直接作用外,相应加强α受体激动对DAD与TA的抑制亦是其中重要原因之一.

AIM: To compare the effects of phenyle-phrine (Phe) on DAD and TA in the absence or presence of propranolol (Pro). METHODS: Using intracellular microelectrode methods to record transmembrane potentials in sheep Purkinje fibers. RESULTS: Perfused Phe 1 μmol·L-1 for 60 min, in the absence of Pro, Phe increased the amplitude of DAD from 7. 5±1. 2 to 9. 0±2. 0 mV (n= 8, P<0. 05), nonsignificantly changed the duration of DAD and induced TA in 3/11 preparations; but in the presence of Pro 0. 5umol .L-1 blocking B-adrenoceptors, the amplitude of DAD increased from 7. 2±1. 8 to 8. 3±2. 1 mV at the first 20 min (n = 8, P<0. 01), and then decreased to 6. 3±1. 6 mV, the duration of DAD prolonged from 192±17 to 280±27 ms (n= 8, P<0. 01 vs control), meanwhile Phe could suppress the TA induced by acetyl-strophanthidin and this effect was blocked by prazosin. CONCLUSION : When Pro is efficiently used in abolishing arrhythmias evoked by catecholmines, apart from directly blocking β-adrenoceptors, relatively aggravating excitation of α-adrenoceptors to suppress DAD and TA is one of the important reasons.