Tri carb 2910tr liquid scintillation analyser

To test metformin cellular uptake, iPSC-MSCs were washed once with prewarmed KRH buffer (125 mM NaCl, 4.8 mM KCl, 1.2 mM CaCl₂, 1.2 mM MgSO₄, 1.2 mM KH₂PO₄, 25 mM HEPES, 5.6 mM glucose, pH 7.4). After 10 min incubation with 10 μM [¹⁴C]-metformin plus 40 μM unlabelled metformin with or without 10 μM cimetidine, a known OCT inhibitor, the uptake was halted by removing the buffer and washing the cells with ice-cold KRH buffer three times. Metformin was obtained from Calbiochem (Gibbstown, NJ, USA). Cells were lysed in 300 μl 1% Triton X-100 and 250 μl cell lysates were transferred to scintillation tubes containing 3 ml Econo-Safe™ economical biodegradable cocktail (Research Products International, Mount Prospect, IL, USA). Radioactivity was counted in a Tri-Carb 2910TR liquid scintillation analyser (Perkin Elmer, Boston, MA, USA) (Chen et al., 2014 (link)).