Figure 9. La³⁺ uptake in transfected CHO cells and rat neonatal cardiac myocytes.

A, CHO cells expressing NCX1.1 were treated with ATP + Tg 10 min before beginning recording. At 8 min before recording, cells were treated with gramicidin in 100/40 Na/K-PSS containing 30 μm EGTA. NCX activity was initiated by superfusing 15 ml of 20 μm LaCl₃ in 100/40 Na/K-PSS (trace a) over a 50–60 s interval, or by rapidly removing the pre-incubation medium and replacing it with 1 ml of 20 μm LaCl₃ in 100/40 Na/K-PSS (trace b). (n = 3). B, neonatal rat myocytes were treated with 10 mm caffeine plus 2 μm Tg 10 min prior to beginning recordings. Subsequently, the cells were treated exactly as described for panel A (n = 5). The bars below the traces in panels A and B denote the duration of solution superfusion.