FIG. 1.

Rate of glucose consumption in endothelial cells is not dependent on glucose concentration in media. Confluent plates of HRECs were cultured in 5 mmol/l (♦), 15 mmol/l (▴), 20 mmol/l (•), or 25 mmol/l (▪) glucose for 2, 4, 8, 16, 32, and 64 h. HRECs, HRPEs, and HMCs were cultured in 5 mmol/l (white bars) or 25 mmol/l (black bars) glucose for 24 h (inset). Glucose consumption was determined as a rate of decrease in glucose concentration in the media normalized to total cellular protein and plotted against glucose concentration in the media. Nonlinear least squares regression analysis demonstrated that the dependency can be best fitted by the equation Y = 175.09 ± 2.17 nmol glucose · mg⁻¹ protein · h⁻¹ with correlation coefficiency of 0.927, describing a zero-order kinetics reaction. As presented in the inset, HRECs consumed extremely low amounts of glucose compared with HRPEs and HMCs, and there was no increase in glucose consumption in HRECs cultured in 25 mmol/l glucose unlike in the HRPE and HMC cultures. Results represent means ± SD; n = 3 for HRPEs, 4 for HMCs, and 6 for HRECs; *P < 0.05.