Hise M K, Steplock D A, Weinman E J
Life Sci. 1986 Sep 1;39(9):831-5. doi: 10.1016/0024-3205(86)90462-5.
The possible role of progressive methylation of phosphatidylethanolamine to phosphatidylcholine on sodium transport was examined in a suspension of rabbit proximal convoluted tubules. The relation between progressive methylation and the action of parathyroid hormone on sodium transport in this nephron segment was also determined. Incubation of the suspended tubules for 10 minutes at 37 degrees C with 200 microM S-adenosyl-L-[3H]-methyl methionine, a methyl donor, revealed a significant rate of de-novo phosphatidylcholine synthesis. The inactive adenosine analogue, 3-deazaadenosine (DZA), had a significant inhibitory effect on lipid methylation. Despite the inhibition of methylation by DZA, the ouabain sensitive component of oxygen consumption, an index of sodium transport, was not affected. PTH significantly inhibited ouabain sensitive oxygen consumption but had no effect on the methylation of phosphatidylethanolamine. Inhibition of methylation by DZA, did not affect the inhibitory effect of PTH on oxygen consumption. These studies demonstrate that in the proximal convoluted tubule of the rabbit the progressive methylation pathway is present and that inhibition of this pathway does not affect sodium transport. In addition, these studies suggest that the inhibitory effect of PTH on sodium transport is not mediated by the methylation pathway.
在兔近端曲管悬液中研究了磷脂酰乙醇胺逐步甲基化生成磷脂酰胆碱在钠转运中的可能作用。还确定了逐步甲基化与甲状旁腺激素对该肾单位节段钠转运作用之间的关系。将悬浮的肾小管在37℃下与甲基供体200微摩尔S-腺苷-L-[3H]-甲硫氨酸孵育10分钟，显示出显著的磷脂酰胆碱从头合成速率。无活性的腺苷类似物3-脱氮腺苷（DZA）对脂质甲基化有显著抑制作用。尽管DZA抑制了甲基化，但作为钠转运指标的哇巴因敏感的耗氧成分未受影响。甲状旁腺激素显著抑制哇巴因敏感的耗氧量，但对磷脂酰乙醇胺的甲基化无影响。DZA对甲基化的抑制并不影响甲状旁腺激素对耗氧量的抑制作用。这些研究表明，在兔近端曲管中存在逐步甲基化途径，并且该途径的抑制不影响钠转运。此外，这些研究表明甲状旁腺激素对钠转运的抑制作用不是由甲基化途径介导的。
