Effect of carnitine on foetal rat lung dipalmitoyl phosphatidylcholine content and lung morphology. Carnitine and lung surfactant, I.

Abstract

Lungs of foetal rats between the 16th and 20th gestational day (total gestation lasting 22 days) were examined. There was a striking increase of both total phosphatidylcholine and dipalmitoyl phosphatidylcholine from day 19 to 20 of gestation. The carnitine content increased continuously from day 17 both in the foetal lungs and livers. In both organs, the increase in short-chain acylcarnitine was more pronounced than the increase in free carnitine. Compared with an untreated control group, treatment of the mother with L-carnitine (from day 16 to 18 of gestation, with 60, 80, and 100 mg/kg.d L-carnitine, respectively) resulted in significant increases in both total phospholipid (p less than 0.05 in all treated groups) and dipalmitoyl phosphatidylcholine (p less than 0.05, p less than 0.01, p less than 0.001, corresponding to maternal treatment with 60, 80, 100 mg/kg.d, respectively) on the 19th gestational day. The results are in accordance with morphological evaluations: with increasing carnitine-dosage, increasing numbers of lamellar bodies in type II cell progenitors were found. The enhanced dipalmitoyl phosphatidylcholine content is a consequence of enhanced phospholipid synthesis in remarkably undifferentiated type II cells largely lacking membrane structures and cell organelles capable of phospholipid synthesis. Thus, in general, carnitine treatment seems to stimulate foetal lung phospholipid synthesis, thereby enhancing the dipalmitoyl phosphatidylcholine content.