Metabolism of intratracheally administered unsaturated phosphatidylcholines in adult rabbits.
Twenty-five adult rabbits were each injected intratracheally with a solution containing 1-palmitoyl-2-[3H]palmitoyl phosphatidylcholine (DPPC) and 1-palmitoyl-2-[14C]oleoyl-PC that had been associated with with 32P-labeled natural rabbit surfactant. The animals were killed in groups of 5 at 1, 4, 8, 15 and 24 h after isotope injection. Isotope recovery and PC specific activities were measured in alveolar washes, lung homogenates, lamellar bodies and microsomes. The percent clearance per h of PC was very similar for the three labels and were; 3.56, 3.44 and 3.00%, respectively, for the 3H-, 14C- and 32P-labeled PC in the total lung (alveolar wash plus lung homogenate) and 3.84, 3.79 and 3.70%, respectively, for alveolar wash alone. The intracellular pathways of the three labels were assessed by comparing the specific activities in the lamellar bodies over 24 h as well as comparing the ratios of lamellar body to microsome specific activities over this period. These ratios were very similar for the monoenoic and saturated PC labels over time, indicating comparable recycling. In a separate experiment, three other unsaturated species; 1,2-[14C]dioleoyl-PC, 1-palmitoyl-2-[14C]linoleoyl-PC, and 1-palmitoyl-2-[14C]arachidonyl-PC were compared to 1-palmitoyl-2-[14C]oleoyl-PC. Recovery in the alveolar wash and total lung were similar at 16 h for all four labeled phospholipids. The intracellular pathways were also similar, except for the arachidonyl compound. More relative to the lamellar bodies as compared to the other. Thus, the catabolic pathways were similar for the saturated and unsaturated PC species initially present in the airspaces. The only metabolic difference between the compounds appears to be in the intracellular handling of the arachidonic species.
Lewis
J
J
Department of Pediatrics, Harbor-UCLA Medical Center, Torrance 90509.
Jobe
A
A
D015060:1,2-Dipalmitoylphosphatidylcholine / Q000008:administration & dosage / Q000378:metabolism*; D000284:Administration, Oral; D000818:Animals; D002250:Carbon Radioisotopes; D007700:Kinetics; D008081:Liposomes; D008168:Lung / Q000378:metabolism*; D008861:Microsomes / Q000378:metabolism; D015388:Organelles / Q000378:metabolism; D010713:Phosphatidylcholines / Q000008:administration & dosage / Q000378:metabolism*; D011817:Rabbits; D011865:Radioisotope Dilution Technique; D014316:Tritium
D002250:Carbon Radioisotopes; D008081:Liposomes; D010713:Phosphatidylcholines; D014316:Tritium; D015060:1,2-Dipalmitoylphosphatidylcholine; C028694:1-palmitoyl-2-oleoylphosphatidylcholine