Figure 10.

The effects of an approximately 50% inhibition of Na⁺, K⁺‐ATPase function with 10 μm strophanthidin on the Ca²⁺ transient and SR Ca²⁺ content of myocytes isolated from sham‐operated hearts

A, application of 10 μm strophanthidin produced a 47 ± 7% reduction of Na⁺,K⁺‐ATPase function (assessed using 8 cells isolated from 3 hearts); scatter plot shows mean (95% CI). B, typical effect of 10 μm strophanthidin on the electrically stimulated and caffeine‐evoked Ca²⁺ transients (caffeine was applied at the arrows). C, pooled data from these experiments; ^*** P < 0.001; N = 38/4. D, pooled data from voltage clamp experiments measuring Na⁺/Ca²⁺ exchange current on application of caffeine during protocols similar to that illustrated in B. Student's t test, ^*** P < 0.001, n/N = 21/4. Scatter plots show mean (95% CI).