[Effect of lipopolysaccharide on the proliferation of rat VSMCs in vitro]

In cultured vascular smooth muscle cells(VSMCs) of SD rat, it was found that 1 x 10(-7) - 1 x 10(-5) kg/L lipopolysaccharide(LPS) markedly stimulated proliferation and DNA synthesis of VSMCs in a dose dependent manner (P<0.05).A time-dependent marked inhibition in proliferation, DNA synthesis and viability of VSMCs (P<0.01)could be obtained by 5 x 10(-4) - 10(-3)kg/L LPS. The inhibitory effect of LPS could be prevented by L-NNA, which reduced NO production by inhibiting NOS. NO3- and NO2- of LPS group markedly increased(P<0.01):48 h group vs 24 h group increased by 9.1%,72 h group vs 48 h group increased by 4.5%. When 5 x 10(-4) - 10(-3) kg/L LPS was added, positive immunohistochemical staining of inductive nitric oxide synthase could be observed. These results suggest that LPS of low dose stimulated the proliferation and the DNA synthesis of VSMCs, while LPS of high dose markedly inhibited them probably due to the increased NO production.