Figure 1
Effect of extracellular nucleotides on platelet extract-induced mitogenic responses in VVEC. (A): Growth-arrested VVEC (72 hrs in serum-free DMEM) were stimulated with platelet extracts (6.4, 16 and 64 μg/ml) with or without ATP (100 μM) or a mixture of non-hydrolyzable nucleotide analogs (MeSATP, ATPγS, MeSADP, ADPβS, 100 μM each) in the presence of 0.125 μCi [3H]-thymidine for 24 hrs. Incorporated radioactivity was determined in total cell lysates as described in "Methods". Data represent the means ± SE from three independent experiments; * p < 0.05, ** p < 0.01 vs. nonstimulated control; (B): VVEC were grown in DMEM/1% FBS in the presence of platelet extracts (6.4, 16, and 64 μg/ml), extracellular ATP (100 μM), or combination of both. Incubation media with all indicated components was changed daily. Cell proliferation rate was assessed using a fluorescent CyQuant proliferation kit (Invitrogen). Data represent the means ± SE from three independent experiments; * p < 0.05, ** p < 0.01 vs. nonstimulated control (48 hrs); # p < 0.05 vs. nonstimulated control (60 hrs); # # p < 0.05 vs. ATP-stimulated cells (60 hrs). No significant differences were observed between platelet-extract stimulated cells vs. platelet extract- and ATP-stimulated cells at 48 and 60 hrs (p > 0.05).