Rasmussen H H, Singer D H, Ten Eick R E
Am J Physiol. 1986 Aug;251(2 Pt 2):H331-9. doi: 10.1152/ajpheart.1986.251.2.H331.
Specimens of right atrial appendage from 106 patients were incubated in cold Tyrode solution, and transmembrane resting potentials (Em) were recorded during rewarming at selected temperatures. Rewarming caused a transient hyperpolarization to develop. The hyperpolarization had a temperature threshold between 17 and 22 degrees C and was inhibited by acetylstrophanthidin. Acetylcholine (ACh) induced a depolarization during early rewarming in 7, 10, 20, and 40 mM K+, indicating that Em hyperpolarized to a potential negative to the equilibrium potential for K+. ACh had no effect after some decline of Em, and hyperpolarization was induced by ACh when Em had reached steady state. The relationship between [K+] in the bulk phase of the superfusate [( K]b) and the "reversal potentials" for the ACh effect was log linear and had a slope of 61.7 mV per tenfold change in [K]b. The relationship between [K]b and hyperpolarization was studied in the presence of 0.5 mM Ba2+. The apparent [K]b resulting in half-maximal pump-induced hyperpolarization was 1.3 mM. The data indicate that human atrium can pump Na+ electrogenically and that the characteristics of the Na+ pump-induced hyperpolarization resemble those described for cardiac tissue from several other mammalian species.
对106例患者的右心耳标本在冷台氏液中进行孵育，并在选定温度复温过程中记录跨膜静息电位（Em）。复温导致短暂的超极化产生。该超极化的温度阈值在17至22摄氏度之间，并被乙酰毒毛花苷抑制。在复温早期，乙酰胆碱（ACh）在7、10、20和40 mM钾离子浓度下诱导去极化，表明Em超极化至钾离子平衡电位的负值。Em有所下降后，ACh无作用，而当Em达到稳态时，ACh可诱导超极化。灌流液总体相中的[K⁺]（[K]b）与ACh效应的“反转电位”之间的关系呈对数线性，[K]b每十倍变化时斜率为61.7 mV。在存在0.5 mM Ba²⁺的情况下研究了[K]b与超极化之间的关系。导致泵诱导超极化达到半数最大值时的表观[K]b为1.3 mM。数据表明，人心房可进行电致钠泵活动，且钠泵诱导超极化的特征类似于其他几种哺乳动物心脏组织所描述的特征。
