Delayed afterdepolarizations and triggered activity induced in feline Purkinje fibers by alpha-adrenergic stimulation in the presence of elevated calcium levels.
Delayed afterdepolarizations and triggered activity induced in feline Purkinje fibers by alpha-adrenergic stimulation in the presence of elevated calcium levels.
复制标题
在钙水平升高的情况下，通过α-肾上腺素能刺激，延迟后去极化并触发猫浦肯野纤维的活动。
DOI：
10.1161/01.cir.70.6.1074
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发表时间：
1984
期刊：
影响因子：
37.8
通讯作者：
Myerburg,RJ
中科院分区：
文献类型：
--
作者：
Kimura,S;Cameron,JS;Kozlovskis,PL;Bassett,AL;Myerburg,RJ
我们研究了α-肾上腺素能刺激诱导延迟后除极和触发活动的猫心脏浦肯野纤维中的存在下，一个升高的Ca ++浓度的能力。当细胞外Ca~（++）浓度为2.7 - 8.1 mM时，在200 - 500 msec的驱动周期内不能诱导延迟后除极。然而，当Ca~（++）浓度为8.1 mM时，在5 × 10~（-7）M普萘洛尔的存在下加入10~（-5）M苯丙氨酸，10个制备物中有8个引起延迟后除极;从三种制剂中记录非驱动触发的动作电位。这些后电位可被5 × 10（-7）M哌唑嗪或10（-6）M酚妥拉明完全抑制。在5 × 10（-7）M普萘洛尔存在下，10（-5）M苯肾上腺素延长动作电位时程，这种作用可被5 × 10（-7）M哌唑嗪抑制。浓度为5 × 10（-6）M的甲氧胺也可增强所有三种研究制剂的延迟后去极化。这些结果表明，在猫心脏Ca ++水平升高的情况下，α-肾上腺素能刺激可以诱导后电位。α-肾上腺素能受体的刺激可能是在Ca ++负载条件下（如缺血和冠状动脉再灌注）心律失常的原因。
We studied the ability of alpha-adrenergic stimulation to induce delayed afterdepolarizations and triggered activity in Purkinje fibers from cat hearts in the presence of an elevated Ca++ concentration. Delayed afterdepolarizations could not be induced at drive cycle lengths of 200 to 500 msec in the presence of extracellular Ca++ concentrations of 2.7 to 8.1 mM. However, the addition of 10(-5)M phenylephrine in the presence of 5 X 10(-7)M propranolol elicited delayed afterdepolarizations in eight of 10 preparations at a Ca++ concentration of 8.1 mM; nondrive-triggered action potentials were recorded from three of the preparations. These afterpotentials were completely suppressed by 5 X 10(-7)M prazosin or 10(-6)M phentolamine. In the presence of 5 X 10(-7)M propranolol, 10(-5)M phenylephrine prolonged action potential duration and this effect was suppressed by 5 X 10(-7)M prazosin. Methoxamine, at a concentration of 5 X 10(-6)M, was also observed to potentiate delayed afterdepolarizations in all of three preparations studied. These results demonstrate that alpha-adrenergic stimulation can induce afterpotentials in the presence of elevated Ca++ levels in cat hearts. Stimulation of alpha-adrenoceptors may be responsible for arrhythmias under Ca++-loaded conditions such as ischemia and coronary reperfusion.