Studies on the effects of betamethasone, L-carnitine, and betamethasone-L-carnitine combinations on the dipalmitoyl phosphatidylcholine content and phosphatidylcholine species composition in foetal rat lungs.

Administration of L-carnitine or betamethasone to pregnant rats failed to increase either the total phospholipid or dipalmitoylphosphatidylcholine (DPPC) contents in foetal rat lungs on the 20th day of gestation, compared to controls. The combined administration of betamethasone (0.3 mg/kg) and L-carnitine (80 mg/kg) resulted in a pronounced increase of dipalmitoylphosphatidylcholine (7.8 +/- 2.5 mg/g dry weight) compared with the control group (5.4 +/- 1.8 mg/g dry weight), and compared with the groups receiving betamethasone (5.9 +/- 1.9 mg/g dry weight) or L-carnitine (5.6 +/- 1.5 mg/g dry weight) alone. The proportion of dipalmitoylphosphatidylcholine in the phosphatidylcholine species increased from 20.9 +/- 2.1% in the foetal lungs of the control group to 22.6 +/- 5.0% in the L-carnitine group, to 24.3 +/- 3.3% (p less than 0.01) in the betamethasone-L-carnitine (20 mg/kg) group, to 25.2 +/- 3.5% (p less than 0.01) in the betamethasone group, to 27.1 +/- 2.6% (p less than 0.01) in the betamethasone-L-carnitine (40 mg/kg) group, and to 28.4 +/- 3.7% (p less than 0.01) in the betamethasone-L-carnitine (80 mg/kg) group, while the palmitic acid portion in the phosphatidylcholine fatty acids was nearly unchanged. A pronounced increase of palmitoyl-myristoyl phosphatidylcholine (PC-30), the second disaturated phosphatidylcholine species present in lungs in significant amounts beside dipalmitoylphosphatidylcholine, was noted only in betamethasone treated animals. Furthermore, after betamethasone and betamethasone-L-carnitine treatment, a significant diminution (p less than 0.01) of the proportion of palmitoyl-palmitoleyl phosphatidylcholine (16 : 0/16 : 1-PC) in the phosphatidylcholine species was demonstrated.(ABSTRACT TRUNCATED AT 250 WORDS)