Influence of (DL)-propranolol and Ca2+ on membrane potential and amino acid transport in Ehrlich ascites tumor cells.
Influence of (DL)-propranolol and Ca2+ on membrane potential and amino acid transport in Ehrlich ascites tumor cells.
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(DL)-普萘洛尔和 Ca2 对艾利希腹水肿瘤细胞膜电位和氨基酸转运的影响。
DOI：
10.1016/0005-2736(78)90054-8
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发表时间：
1978
期刊：
影响因子：
--
通讯作者：
P. C. Laris
中科院分区：
文献类型：
--
作者：
H. Pershadsingh;R. Johnstone;P. C. Laris
（1）（DL）-普萘洛尔和Ca ~（2+）显示出改变埃利希腹水肿瘤细胞的跨膜电位差，这是通过花青染料，3，3 ′-二丙基-2，2 ′-硫代二碳花青碘化物测量的，其荧光强度作为膜电位的函数而变化。(2)由这些试剂引起的膜电位的变化依赖于外部K+浓度的方式，这表明潜在的变化是由于质膜对K+的渗透性的特定增加。(3)Na+依赖的氨基酸转运在普萘洛尔的存在下，可以通过改变外部K+浓度（K+ o）调制。普萘洛尔在低K+ o时刺激摄取起始速率，在高K+ o时抑制摄取起始速率。在普萘洛尔存在下，转运速率的变化几乎与[K+] o的自然对数成正比。(4)通过用鱼藤酮预孵育的细胞的ATP消耗废除了用普萘洛尔作为K+ o的函数观察到的荧光和氨基酸摄取的变化。在Ca 2+存在下，用葡萄糖恢复细胞ATP可恢复普萘洛尔引起的荧光和氨基酸转运变化。(5)响应普萘洛尔的荧光变化和氨基酸转运变化是pH依赖性的，在pH 6时几乎没有影响。(6)它的结论是Na+依赖的氨基酸摄取率是膜电位的函数，并依赖于Na+的电化学电位差。
(1)(DL)-Propranolol and Ca2+ are shown to alter the transmembrane potential difference of Ehrlich ascites tumor cells as measured by means of the cyanine dye, 3, 3'-dipropyl-2, 2'-thiodicarbocyanine iodide, whose fluorescent intensity changes as a function of membrane potential.(2) The changes in membrane potential elicited by these agents are dependent of the external K+ concentration in a manner which suggest that the potential changes result from a specific increase in the permeability of the plasma membrane to K+.(3) Na+-dependent amino acid transport in the presence of propranolol can be modulated by varying the external K+ concentration (K+ o). The initial rate of uptake is stimulated by propranolol at low K+ o and inhibited at high K+ o. The change in transport rate is nearly directly proportional to the natural logarithm of [K+] o in the presence of propranolol.(4) ATP depletion of the cells by preincubation with rotenone abolishes the changes in fluorescence and amino acid uptake seen with propranolol as a function of K+ o. Restoration of cellular ATP with glucose in presence of Ca2+ restores both fluorescence and amino acid transport changes which occur in response to propranolol.(5) The fluorescence changes and amino acid transport changes in response to propranolol are pH dependent, with little effect seen at pH6.(6) It is concluded that the rate of Na+-dependent amino acid uptake is a function of membrane potential and is dependent on the electrochemical potential difference for Na+.