Kinetic parameters as determined from double-reciprocal plot analyses of Ca2+-dependences of the rate of Na+ i-dependent Ca2+uptake into cells expressing NCX1, NCX3, or NCX1 mutants in the presence or absence of KB-R7943 .
| Treatment | Km(Ca) | Vmax | |
|---|---|---|---|
| mM | nmol/mg/30 s | ||
| NCX1 | Control | 0.19 ± 0.03 | 20 ± 1.2 |
| KB-R7943 (3 μM) | 0.23 ± 0.03 | 13 ± 1.01-150 | |
| KB-R7943 (10 μM) | 0.38 ± 0.031-150 | 9 ± 0.51-150 | |
| N1-V820G | Control | 0.21 ± 0.02 | 15 ± 0.7 |
| KB-R7943 (1 μM) | 0.24 ± 0.02 | 11 ± 0.81-150 | |
| KB-R7943 (3 μM) | 0.33 ± 0.031-150 | 8 ± 0.71-150 | |
| N1-Q826V | Control | 0.22 ± 0.01 | 13 ± 1.0 |
| KB-R7943 (1 μM) | 0.25 ± 0.04 | 10 ± 1.1 | |
| KB-R7943 (3 μM) | 0.31 ± 0.041-150 | 7 ± 0.31-150 | |
| N1-G833C | Control | 0.20 ± 0.01 | 14 ± 0.8 |
| KB-R7943 (3 μM) | 0.23 ± 0.04 | 12 ± 1.0 | |
| KB-R7943 (10 μM) | 0.21 ± 0.02 | 13 ± 0.5 | |
| NCX3 | Control | 0.18 ± 0.02 | 15 ± 1.3 |
| KB-R7943 (1 μM) | 0.20 ± 0.03 | 10 ± 0.81-150 | |
| KB-R7943 (3 μM) | 0.26 ± 0.021-150 | 6 ± 0.41-150 |
The initial rates of 45Ca2+ uptake were measured in the presence of 0.067 to 2 mM CaCl2 and at 0 to 10 μM KB-R7943 and analyzed as shown previously (Iwamoto and Shigekawa, 1998). Values are presented as means ± S.E. (n = 3).
↵1-150 p < 0.05 vs. control.