Thrombin-induced mitogenesis of vascular SMC is partially mediated by autocrine production of PDGF-AA.
Previous studies have shown that alpha-thrombin (Thr) is a mitogen for cultured smooth muscle cells (SMC), but controversy exists concerning mechanisms of growth stimulation. The purpose of these studies was to determine whether autocrine production of platelet-derived growth factor-AA (PDGF-AA) mediated Thr-induced SMC mitogenesis. SMC derived from aortae of Sprague-Dawley rats were grown to confluence, growth arrested in serum-free medium, and treated. Conditioned medium (CM) was harvested by adding bovine serum albumin as a carrier and hirudin to neutralize residual Thr. Results demonstrated that CM from Thr-treated SMC (Thr CM) had increased mitogenic activity compared with control CM (Cnt CM) and that PDGF-AA levels were increased 12-fold in Thr CM compared with Cnt CM. The excess mitogenic activity in Thr CM was markedly inhibited by PDGF-AA-neutralizing antibodies. Cotreatment with Thr and PDGF-AA-neutralizing antibodies resulted in a 30% decrease in Thr-induced [3H]thymidine incorporation. These results demonstrate that autocrine production of PDGF-AA partially mediated Thr-induced SMC mitogenesis.
Stouffer
G A
GA
Department of Medicine, University of Virginia School of Medicine, Charlottesville 22908.
Sarembock
I J
IJ
McNamara
C A
CA
Gimple
L W
LW
Owens
G K
GK
D000818:Animals; D017077:Culture Media, Conditioned / Q000494:pharmacology; D006629:Hirudins / Q000494:pharmacology; D008934:Mitogens / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D010982:Platelet-Derived Growth Factor / Q000096:biosynthesis* / Q000494:pharmacology; D013917:Thrombin / Q000494:pharmacology*; D013936:Thymidine / Q000378:metabolism
D017077:Culture Media, Conditioned; D006629:Hirudins; D008934:Mitogens; D010982:Platelet-Derived Growth Factor; C075278:platelet-derived growth factor A; D013917:Thrombin; D013936:Thymidine