摘要
用乙酰毒毛旋花子甙元（ＡＳ）０．０５μｍｏｌ／Ｌ诱发绵羊心浦肯野纤维产生稳定的瞬时性内向离子流（Ｉｔｉ），用普萘洛尔０．５μｍｏｌ／Ｌ阻断β受体，观察α受体激动剂苯肾上腺素（ＰＥ）０．３，１．０μｍｏｌ／Ｌ对Ｉｔｉ幅值与时程的影响。ＰＥ１．０μｍｏｌ／Ｌ灌流２０，５０ｍｉｎ时Ｉｔｉ幅值分别由对照值１２．８±１．９ｎＡ减小至１０．７±１．２ｎＡ（ｎ＝５，Ｐ＜０．０５）与９．６±１．９ｎＡ（ｎ＝５，Ｐ＜０．０１）；ＩｔｉＤ５０时程分别由对照值１４５±２４．４ｍｓ延长至１８３．３±２８．１ｍｓ（ｎ＝５，Ｐ＜０．０５）与２０７．５±３４．２ｍｓ（ｎ＝５，Ｐ＜０．０１），ＰＥ对Ｉｔｉ的抑制作用呈剂量依赖性与时间依赖性。Ｉｔｉ到达峰值的时间和回复到基线的时间都延长，提示ＰＥ作用下Ｉｔｉ通道动力学发生了变化。如果在β受体激动剂异丙肾上腺素（ＩＳＯ）１．０μｍｏｌ／Ｌ增强Ｉｔｉ的基础上，ＰＥ１．０μｍｏｌ／Ｌ灌流１０ｍｉｎ，对Ｉｔｉ幅值的抑制及时程的延长作用更显著，Ｉｔｉ幅值由对照值１５．６±３．２ｎＡ减小到１０．３±２．２ｎＡ；ＩｔｉＤ５０由９２．５±１４．３ｍｓ延长到１３２．５±３６．０ｍｓ（ｎ＝５，Ｐ＜０．０１）。
Acetyl strophanthidin (AS) 0. 05 μmol/L was used to induce a stable model of transient inward current (Iti) of sheep Purkinje fibers. The effect of the alpha-adrenoceptor agonist phenylephrine (PE) 0. 3, 1. 0 μmol/L on the amplitude and duration of Iti was observed in the presence of propranolol 0. 5 μmol/L to block the β-adrenoceptor.When the preparation was Perfused with PE 1. 0 βmol/L for 20, 50 min,the amplitude of Iti decreased from control value 12. 8 ± 1. 9 nA to respectively 10.7±1.2nA (n=5,P<0.05) and 9. 6± 1. 9 nA (n= 5, P<0. 01 ). The D50 of Iti prolonged correspondingly from control value 145± 24. 4 ms to 183. 3 ± 28. 1 ms (n=5,P<0.05) and 207. 5 ± 34. 2 ms (n= 5, P<0. 01 ). The inhibitory effect of PE on Iti showed a dose- and time-dependent manner. Both the time for arrival of the peak value and for return to baseline of Iti prolonged. This suggests that the kinetics of Iti channel changed in the presence of PE. When the Iti was enhanced by β adreceptor agonist isoprenaiine (ISO) 1. 0 μmol/L, the addition of PE 1. 0 μmol/L to the Perfusate for 10min,the inhibitory effect become more pronounced, the amplitude of Iti decreased from 15.6± 3. 2 nA to 10. 3±2. 2 nA and the D5o of Iti prolonged from 92.5± 14.3 ms to 132. 5±36. 0 ms (n=5, P<0. 01).
出处
《生理学报》
CAS
CSCD
北大核心
1995年第4期387-393,共7页
Acta Physiologica Sinica
基金
国家自然科学基金
关键词
心肌
苯肾上腺素
肾上腺素能受体
心律失常
phenyleprine
edrenoceptor
transient inward current
Purkinje fibers
