[Roles of gap junctions in proliferation mediated by Hcy in the spontaneous hypertensive rat vascular smooth muscle cells].

OBJECTIVE: To investigate whether homocysteine (Hcy) participates the proliferation of the spontaneously hypertensive rat(SHR) vascular smooth muscle cell (VSMCs) and the molecular mechanism.

METHODS: The rat's arota were removed. The primary SHR VSMCs were isolated and cultured in vitro, then the SHR VSMCs were divided into four groups: (1) control group, (2) Hcy group, (3) 18alpha-glycyrrhetinic acid (GA) group, (4) Hcy + 18alpha-GA group. We detected proliferation of the SHR VSMCs by MTT and flow cytometry. The expression and co-localization of the connexin (Cx) 43 and Cx40 proteins in the SHR VSMCs were deteced by immunofluorescence. The expression of the Cx43 and Cx40 proteins in SHR VSMCs were detected by Western blot. The molecular dye transfer method (scrape dye transfer method) was applied to detect the gap junction function in the SHR VSMCs.

RESULTS: (1) The Cx43 and Cx40 proteins expression in the SHR VSMCs were positive, confocal microscopy supported the co-localization of Cx43 and Cx40 in the cytoplasm. (2) The S value deteced by cell cycle and A value detected by MTT in the Hcy group were increased obviously compared with those in the control group (P < 0.05), decreased in 18alpha-GA group (P < 0.05). Compared with the Hcy group, the S and A value in the Hcy + 18alpha-GA group were significantly decreased, respectively (P < 0.05). (3) The expression of Cx43 and Cx40 proteins in Hcy group were increased compared with the control group (P < 0.05), decreased in 18alpha-GA group (P < 0.05). Compared with the Hcy group, the expression of Cx43 and Cx40 proteins in the Hcy + 18alpha-GA group were significantly decreased, respectively (P < 0.05). (4) The function of gap junction detected by scrape dye transfer method in the Hcy group were enhanced compared with the control group (P < 0.05), weakened in the 18alpha-GA group (P < 0.05). Compared with the Hcy group,the function of gap junction in the Hcy + 18alpha-GA group was significantly weakened (P < 0.05).

CONCLUSION: Hcy can enhance the function of gap junctional to stimulate the proliferation of SHR VSMCs through the expression of Cx43 and Cx40 proteins promoted.