Pitts B J, Okhuysen C H
Am J Physiol. 1984 Nov;247(5 Pt 2):H840-6. doi: 10.1152/ajpheart.1984.247.5.H840.
We have previously reported that palmitoyl carnitine is a potent inhibitor of Na+-K+-ATPase. Recently, Owens et al. [Am. J. Physiol. 242 (Heart Circ. Physiol. 11): H456-H461, 1983] reported that palmitoyl carnitine did not inhibit Na+-K+-ATPase activity of their cardiac sarcolemmal preparation that had been isolated without the use of detergents. We have investigated this using a similar preparation. Palmitoyl carnitine appears to be a much less effective inhibitor of the sarcolemmal preparation at lower concentrations because it simultaneously stimulates Na+-K+-ATPase by unmasking latent activity. When this latent activity is exposed by pretreatment with sodium dodecyl sulfate, a marked inhibition by palmitoyl carnitine is then observed. Similar results were obtained with lysophosphatidylcholine (LPC). The concentrations of palmitoyl carnitine and LPC required to inhibit Na+-K+-ATPase are, however, higher than those that cause sarcolemmal permeability changes; consequently, it is improbable that inhibition of the enzyme by these metabolites occurs to any significant extent in vivo.
我们之前曾报道，棕榈酰肉碱是钠钾ATP酶的一种强效抑制剂。最近，欧文斯等人[《美国生理学杂志》242卷（心脏循环生理学11）：H456 - H461，1983年]报道，棕榈酰肉碱对他们未使用去污剂分离的心肌肌膜制剂的钠钾ATP酶活性没有抑制作用。我们使用类似的制剂对此进行了研究。在较低浓度下，棕榈酰肉碱似乎对肌膜制剂的抑制作用要弱得多，因为它同时通过揭示潜在活性来刺激钠钾ATP酶。当这种潜在活性通过用十二烷基硫酸钠预处理而被暴露时，随后会观察到棕榈酰肉碱有明显的抑制作用。溶血磷脂酰胆碱（LPC）也得到了类似的结果。然而，抑制钠钾ATP酶所需的棕榈酰肉碱和LPC的浓度高于引起肌膜通透性变化的浓度；因此，这些代谢产物在体内对该酶的抑制不太可能在任何显著程度上发生。
