AIMTo investigate the influence and mechanisms of 17beta-estradiol on the CTP: phosphorylcholine cytidylyltransferase (CCT) activity from cultured lung explants without serum.

METHODSWe detected the amount of [M-14C] choline incorporation into phosphatidylcholine so as to reflect CCT activity by liquid scintillation.

RESULTS(1) 17beta-estradiol increased the CCT activity in dose-dependence and time-dependence. (2) Both the protein kinase C inhibitor H-7 and calmodulin antagonist W-7 abolished the stimulatory effect of 17beta-estradiol (3 x 10(-6) mol/L) on the CCT activity.

CONCLUSION17beta-estradiol can increase CCT activity in cultured lung explants, its mechanism is related to protein kinase C and calmodulin.

Animals ; Calmodulin ; metabolism ; Choline-Phosphate Cytidylyltransferase ; metabolism ; Culture Media, Serum-Free ; Estradiol ; pharmacology ; In Vitro Techniques ; Lung ; drug effects ; enzymology ; Male ; Protein Kinase C ; metabolism ; Rats ; Rats, Wistar

The effects of endothelin-1 (ET-1) at low concentration (1-100 pmol/L) on the reactive oxygen-induced inhibition of both pulmonary surfactant (PS) lipid synthesis and the activity of CTP: phosphorylcholine cytidylyltransferase (CCT), a rate-limiting enzyme in biosynthesis of phosphoatidylcholine (PC), were studied in cultured lung explants without serum. The xanthine-xanthine oxidase superoxide anion generating system decreased (3)H-choline incorporation into PC in a dose-dependent manner in cultured lung explants. ET-1 reduced both the reactive oxygen-induced decrease in (3)H-choline incorporation and the increase in malondialdehyde (MDA) content of lung tissues, but did not change the levels of antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and the total antioxidant capability in the lung explants. ET-1 enhanced microsomal CCT activity of the lung tissues, while it decreased cytosolic CCT activity of lung tissues. ET-1 also prevented the inhibitive effect of reactive oxygen on microsomal CCT activity in the lung explants. These results suggest that ET-1 at low concentration can protect the microsomal CCT activity and reduce the inhibition of PS lipid synthesis induced by oxidant lung injury. The protective mechanism of ET-1 is not relative to the pulmonary endogenous antioxidant defense system.
Animals ; Choline-Phosphate Cytidylyltransferase ; metabolism ; Endothelin-1 ; administration & dosage ; pharmacology ; Female ; In Vitro Techniques ; Lung ; drug effects ; enzymology ; metabolism ; Male ; Phospholipids ; biosynthesis ; Pulmonary Surfactants ; chemistry ; Rats ; Rats, Wistar ; Reactive Oxygen Species ; toxicity