Platelet-activating factor induces glycogen degradation in fetal rabbit lung in utero.
The role of platelet-activating factor (PAF, 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine) in initiating glycogen breakdown in the fetal rabbit lung was assessed by intraperitoneal administration of this potent ether-linked glycerophospholipid. Forty-five min after in utero injection of PAF (2.5 X 10(-7) mol), fetal pulmonary and hepatic glycogen concentrations were reduced from 326 to 256 and from 9.8 to 6.6 micrograms of glycogen/mg protein, respectively. Glycolytic activity was similarly increased as judged by an elevation of lactate (2-fold) in lung, liver, and plasma upon PAF injection. These actions of PAF were dose- and time-dependent. The glycogenolytic response did not occur when an equimolar dose of the inactive enantiomer, D-PAF was injected. Pretreatment of the fetus with a specific PAF receptor antagonist, SRI-63-441, prevented the PAF response. We have previously demonstrated (Hoffman, D. R., Truong, C. T., and Johnston, J. M. (1986) Biochim. Biophys. Acta 879, 88-96) that PAF biosynthesis and PAF concentrations increase significantly on day 24 of fetal rabbit lung development. A concurrent decrease in pulmonary glycogen concentration at this point of gestation is potentially reflective of the PAF-induced action. Thus, these observations would suggest a role for PAF in the normal physiology of fetal lung maturation.
Hoffman
D R
DR
Department of Biochemistry, Cecil H. & Ida Green Center for Reproductive Biology Sciences, University of Texas Southwestern Medical Center, Dallas 75235.
White
R G
RG
Angle
M J
MJ
Maki
N
N
Johnston
J M
JM
D000818:Animals; D005260:Female; D005333:Fetus; D006003:Glycogen / Q000378:metabolism*; D007700:Kinetics; D007773:Lactates / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000196:embryology; D008112:Liver Glycogen / Q000378:metabolism; D008168:Lung / Q000187:drug effects / Q000196:embryology / Q000378:metabolism*; D010972:Platelet Activating Factor / Q000494:pharmacology*; D011247:Pregnancy; D011817:Rabbits
D007773:Lactates; D008112:Liver Glycogen; D010972:Platelet Activating Factor; D006003:Glycogen