Figure 3.

Intracellular concentrations of carnosine in erythrocytes exposed to different concentrations of carnosine in the medium reveal a biphasic uptake response. Erythrocytes of a healthy volunteer (male, age 29) were incubated in the presence of different concentrations of carnosine. After 4 h of incubation, the intracellular amounts of carnosine were determined using LC-MS and external standards. The concentration inside the erythrocytes was calculated assuming an average erythrocyte volume of 90 × 10⁻¹⁵ L. All measurements have been performed in triplicate. Lines represent the results of a biphasic fit with an R² of 0.997 and the 1st EC50 = 5.86 µM and the 2nd EC50 = 62.65 µM.