Lamers J M, Stinis H T, Montfoort A, Hülsmann W C
Biochim Biophys Acta. 1984 Jul 11;774(1):127-37. doi: 10.1016/0005-2736(84)90283-9.
The effect of fatty acid and acylcarnitine on Ca2+ and Na+ transporting enzymes and carriers was studied in sealed cardiac sarcolemma vesicles of mixed polarity. Palmitoylcarnitine markedly reduced the Na+ gradient-induced Ca2+ uptake. Half-maximal reduction was obtained at 15 microM of the carnitine derivative. In a same concentration range palmitoylcarnitine caused a rapid release of accumulated Ca2+ when added to Ca2+-filled vesicles, which suggests that palmitoylcarnitine increases the permeability of the sarcolemma vesicles to Ca2+. A rapid release of Ca2+ was also observed if Ca2+ was taken up by action of the Ca2+ pump. The (Ca2+ + Mg2+)-ATPase, which most likely drives this active Ca2+ uptake, was 90% increased by 50 microM palmitoylcarnitine and evidence was presented that the acylcarnitine effect again was linked to an alteration of Ca2+ permeability of the vesicles. At the same concentration acylcarnitine was not able to unmask the latent protein kinase, so that probably the sarcolemma ATP permeability was not affected. Palmitoylcarnitine at 25 microM did not affect the ouabain-sensitive (Na+ + K+) -ATPase in native sarcolemma vesicles, however, it inhibited markedly if the enzyme was measured in SDS-treated vesicles. The effect of increased free fatty acid concentration on some of the sarcolemma transporting properties was tested by adding oleate-albumin complexes with different molar ratios to the sarcolemma vesicles. In contrast to molar ratios 1 and 5, the ratio of 7 was able to induce a rapid Ca2+ release and to inhibit (Na+ + K+)-ATPase in either native or SDS-treated vesicles markedly. 22Na release from 22Na-preloaded sarcolemma vesicles was shown to be stimulated by either palmitoylcarnitine (50 microM) or oleate-albumin complex (with a molar ratio of 7). The possible significance of the observed effects of lipid intermediates on ion permeability and (Na+ + K+)-ATPase activity in isolated sarcolemma vesicles for the derangement of cardiac cell function in ischemia is discussed.
在混合极性的密封心肌肌膜囊泡中研究了脂肪酸和酰基肉碱对Ca2+和Na+转运酶及载体的影响。棕榈酰肉碱显著降低了Na+梯度诱导的Ca2+摄取。在15微摩尔的肉碱衍生物时获得半数最大降低效应。在相同浓度范围内，当将棕榈酰肉碱添加到充满Ca2+的囊泡中时，会导致积累的Ca2+快速释放，这表明棕榈酰肉碱增加了肌膜囊泡对Ca2+的通透性。如果Ca2+通过Ca2+泵的作用被摄取，也会观察到Ca2+的快速释放。最有可能驱动这种主动Ca2+摄取的（Ca2+ + Mg2+）-ATP酶，在50微摩尔棕榈酰肉碱作用下增加了90%，并且有证据表明酰基肉碱的作用再次与囊泡Ca2+通透性的改变有关。在相同浓度下，酰基肉碱不能激活潜在的蛋白激酶，因此肌膜ATP通透性可能未受影响。25微摩尔的棕榈酰肉碱对天然肌膜囊泡中的哇巴因敏感的（Na+ + K+）-ATP酶没有影响，然而，如果在SDS处理的囊泡中测量该酶，则会显著抑制。通过向肌膜囊泡中添加不同摩尔比的油酸-白蛋白复合物，测试了游离脂肪酸浓度增加对一些肌膜转运特性的影响。与摩尔比1和5相比，摩尔比7能够诱导快速的Ca2+释放，并在天然或SDS处理的囊泡中显著抑制（Na+ + K+）-ATP酶。从预加载22Na的肌膜囊泡中释放22Na被证明受到50微摩尔棕榈酰肉碱或油酸-白蛋白复合物（摩尔比为7）的刺激。讨论了脂质中间体对分离的肌膜囊泡中离子通透性和（Na+ + K+）-ATP酶活性的观察效应对于缺血时心肌细胞功能紊乱的可能意义。
