Aim: To investigate the effect of vasoactive intestinal peptide (VIP) on pulmonary surfactants (PS) phospholipid synthesis in cultured lung explants.
Methods: Lung explants were cultured with serum-free medium, [methyl-3H]choline incorporation, total phospholipid, phosphatidylcholine, activity of choline-phosphate cytidylyltransferase (CCT) and CCTalpha mRNA level in lung explants were determined.
Results: (1) VIP (10(-10)-10(-7) mol/L) for 16 h promoted [methyl-3H]choline incorporation in dose dependence and VIP (10(-8) mol/L) for 2 h-16 h promoted [methyl-3H]choline incorporation in time dependence. (2) VIP (10(-8) mol/L) enhanced the contents of total phospholipids and phosphatidylcholine in lung explants. (3) VIP (10(-10)-10(-7) mol/L) elevated microsomal CCT activity of lung explants in dose dependence. (4) VIP (10(-8) mol/L) increased expression of CCTalpha mRNA in lung explants and alveolar type II cells (ATII). (5) [D-P-Cl-Phe(6)-Leu(17)]-VIP (10(-6) mol/L), a VIP receptors antagonist, abolished the increase of [3H]choline incorporation, microsomal CCT activity and CCTalpha mRNA level induced by VIP (10(-8) mol/L) in lung explants.
Conclusion: VIP could enhance synthesis of phosphatidylcholine, the major component of pulmonary surfactants by enhancing microsomal CCT activity and CCTalpha mRNA level via VIP receptor-mediated pathway.