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

• Published in: The Journal of biological chemistry Vol. 259; no. 1; pp. 16 - 19
• Main Authors: Philipson, K D, Nishimoto, A Y
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Elsevier Inc 10.01.1984; American Society for Biochemistry and Molecular Biology
• Subjects: Animals; Biological and medical sciences; Biological Transport, Active; Calcium - metabolism; Cell physiology; Dogs; Fundamental and applied biological sciences. Psychology; Kinetics; Membrane and intracellular transports; Membrane Potentials; Molecular and cellular biology; Myocardium - metabolism; Permeability; Phospholipase D - metabolism; Phospholipases - metabolism; Sarcolemma - metabolism; Sodium - metabolism; Heart; Sarcolemma; Vesicle; Fissipedia; Carnivora; Calcium; Phospholipid; Ion transport; Activation; Phospholipase D; Vertebrata; Mammalia; Sodium; Membrane transport; Plasma membrane; Enzymatic digestion; Dog
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(17)43613-1

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.