Figure 1.

Phloretin inhibits zero-trans-glucose influx competitively. Glucose transport was measured rapidly (5 seconds) in the absence (●) and presence (■) of 45 μM (A) or 91 μM (B) phloretin. The full lines represent the fitted Michaelis–Menten curves. A, no phloretin: V_max = 169 ± 2 nmol⋅min⁻¹⋅mg⋅protein⁻¹ and K_m = 0.73 ± 0.01 mM. A, with phloretin: V_max = 169 ± 9 nmol⋅min⁻¹⋅mg⋅protein⁻¹ and K_m ± 2.99 ± 0.36 mM. B, no phloretin: V_max = 198 ± 12 nmol⋅min⁻¹⋅mg⋅protein⁻¹ and K_m = 1.85 ± 0.38 mM. B, with phloretin: V_max = 193 ± 5 nmol⋅min⁻¹⋅mg⋅protein⁻¹ and K_m = 6.35 ± 0.39 mM. In the absence of phloretin, ethanol was added to correct for any solvent effect. The data in A were obtained with one batch of cells, isolated from a single rat. The data in B were measured with another batch of cells, obtained from a different rat.