磷脂酶D对心肌肌膜囊泡中Na⁺-Ca²⁺交换的刺激作用。

Stimulation of Na+-Ca2+ exchange in cardiac sarcolemmal vesicles by phospholipase D.

作者信息

Philipson K D, Nishimoto A Y

出版信息

J Biol Chem. 1984 Jan 10;259(1):16-9.

Abstract

Treatment of canine cardiac sarcolemmal vesicles with phospholipase D resulted in a large stimulation (up to 400%) of Na+-Ca2+ exchange activity. The phospholipase D treatment decreased the apparent Km (Ca2+) for the initial rate of Nai+-dependent Ca2+ uptake from 18.2 +/- 2.6 to 6.3 +/- 0.3 microM. The Vmax increased from 18.0 +/- 3.6 to 31.5 +/- 3.6 nmol of Ca2+/mg of protein/s. The effect was specific for Na+-Ca2+ exchange; other sarcolemmal transport enzymes ((Na+, K+)-ATPase; ATP-dependent Ca2+ transport) are inhibited by incubation with phospholipase D. Phospholipase D had little effect on the passive Ca2+ permeability of the sarcolemmal vesicles. After treatment with 0.4 unit/ml of phospholipase D (20 min, 37 degrees C), the sarcolemmal content of phosphatidic acid rose from 0.9 +/- 0.2 to 8.9 +/- 0.4%; simultaneously, Na+-Ca2+ exchange activity increased 327 +/- 87%. It is probable that the elevated phosphatidic acid level is responsible for the enhanced Na+-Ca2+ exchange activity. In a previous study (Philipson, K. D., Frank, J. S., and Nishimoto, A. Y. (1983) J. Biol. Chem. 258, 5905-5910), we hypothesized that negatively charged phospholipids were important in Na+-Ca2+ exchange, and the present results are consistent with this hypothesis. Stimulation of Na+-Ca2+ exchange by phosphatidic acid may be important in explaining the Ca2+ influx which accompanies the phosphatidylinositol turnover response which occurs in a wide variety of tissues.

摘要

用磷脂酶D处理犬心肌肌膜囊泡，可使Na⁺-Ca²⁺交换活性大幅增强（高达400%）。磷脂酶D处理使依赖胞内Na⁺的Ca²⁺摄取初始速率的表观Km（Ca²⁺）从18.2±2.6微摩尔降至6.3±0.3微摩尔。Vmax从18.0±3.6纳摩尔Ca²⁺/毫克蛋白/秒增至31.5±3.6纳摩尔Ca²⁺/毫克蛋白/秒。该效应对Na⁺-Ca²⁺交换具有特异性；其他肌膜转运酶（（Na⁺，K⁺）-ATP酶；ATP依赖的Ca²⁺转运）与磷脂酶D孵育后会受到抑制。磷脂酶D对肌膜囊泡的被动Ca²⁺通透性影响很小。用0.4单位/毫升磷脂酶D处理（20分钟，37℃）后，磷脂酸的肌膜含量从0.9±0.2%升至8.9±0.4%；同时，Na⁺-Ca²⁺交换活性增加327±87%。磷脂酸水平升高很可能是Na⁺-Ca²⁺交换活性增强的原因。在之前的一项研究中（菲利普森，K.D.，弗兰克，J.S.，和西本莫托，A.Y.（1983年）《生物化学杂志》258，5905 - 5910），我们推测带负电荷的磷脂在Na⁺-Ca²⁺交换中很重要，目前的结果与这一假设相符。磷脂酸对Na⁺-Ca²⁺交换的刺激作用可能对解释多种组织中伴随磷脂酰肌醇周转反应的Ca²⁺内流很重要。