DIFFERENTIAL LABELINGS SUGGEST 2 SPECIFIC PHOSPHOLIPID SUBCLASS HYDROLYSIS PROMOTED BY PDGF-BB IN VASCULAR SMOOTH-MUSCLE CELLS

We have used differential phospholipid subclass labelings performed wi th [H-3]lyso PAF and [H-3] myristic acid into vascular smooth muscle c ells (vSMC) to characterize the subclasses of phospholipid substrates upon different stimulation times with platelet-derived growth factor ( PDGF-BB). In cells labeled with [H-3]lyso PAF, PDGF-BB induced a susta ined hydrolysis of alkyl-PE. In contrast, in [H-3]myristic acid-labele d cells, PDGF-BB promoted a rapid and transitory hydrolysis of diacyl- PC. This hydrolysis was concomitant with an synthesis of diglyceride ( DG) and phosphatidic acid (PA). Thus, both diacyl-PC and alkyl-PE appe ar to be major targets in PDGF-BB stimulation of SMC. These results su ggest that agonists could induce the hydrolysis of precise phospholipi d subclasses leading to a new specificity into the signal transduction cascade. (C) 1996 Academic Press, Inc.