High glucose inhibits retinal capillary pericyte contractility in vitro.

PURPOSE To study the effect of high glucose concentrations on pericyte contractility. METHODS Bovine retinal capillary pericytes were cultured on silicone rubber sheets, which could be seen to wrinkle when a cell contracted. Cells were grown in glucose, or mannitol, in concentrations ranging from 5 to 40 mMol. Pericyte contractility was expressed as the percentage of cells wrinkling the silicone substratum. Observations were made fortnightly for 8 weeks. RESULTS Cells grown in glucose exhibited a dose-dependent inhibition of contractility that was significantly greater than that seen with cells grown in mannitol, which were affected to a lesser extent. After returning to normoglycemic conditions for a further 4 weeks, the contractility of cells grown in lower glucose concentrations recovered partially, but cells grown in 40 mMol glucose did not recover at all. Pericyte proliferation was also impaired by the high-glucose growth medium. CONCLUSIONS Pericyte contractility is inhibited by high glucose concentrations. This is consistent with the hypothesis that increased retinal blood flow may be a factor in the early pathogenesis of diabetic retinopathy.