Further study on the turnover calculation of lung lecithins.

Using the data reported previously by Moriya and Kanoh, the metabolic turnover of rat lung lecithins was calculated on the basis of the new assumption that the formation rate (Va) of lecithins from diacylglycerols did not equal the disappearance rate (Vb) of lecithins because of the presence of precursors other than diacylglycerols. The ratio of Va/Vb was almost the same in dienoic lecithin as that for total lecithins, whereas a very low ratio was found in saturated and hexaenoic species. The turnover time of lung lecithins estimated was markedly shorter than those determined in much later experimental periods after administration of labeled precursors. The reason for this discrepancy was discussed.