%0 Journal Article %T Influences of phenylephrine on delayed afterdepolarization and triggered activity in sheep Purkinje fibers %A SHI Wei-bin %A XU You-qiu %A CHEN Xi-luo %A YU Pei-de %J Acta Pharmacologica Sinica %D 2016 %B 2016 %9 %! Influences of phenylephrine on delayed afterdepolarization and triggered activity in sheep Purkinje fibers %K %X AIM: To compare the effects of phenylephrine (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 mumol.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 0.5 mumol.L(-1) blocking beta-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 acetylstrophanthidin and this effect was blocked by prazosin. CONCLUSION: When Pro is efficiently used in abolishing arrhythmias evoked by catecholmines, apart from directly blocking beta-adrenoceptors, relatively aggravating excitation of alpha-adrenoceptors to suppress DAD and TA is one of the important reasons. %U http://www.chinaphar.com/article/view/6193 %V 16 %N 3 %P 243-246 %@ 1745-7254