Figure 11.

Increasing Na⁺ influx following partial inhibition of the Na⁺, K⁺‐ATPase and SERCA function does not increase the amplitude of the Ca²⁺ transient

A, effects on the Ca²⁺ transient, recorded in myocytes isolated from healthy hearts, of about 50% inhibition of SERCA function with 200 nm cyclopiazonic acid (CPA) when the Na⁺,K⁺‐ATPase has also been inhibited (10 μm strophanthidin, Stroph). The time between the first two traces is 3 min. B, pooled data from these experiments indicating the Ca²⁺ transient amplitude decreases by 30%. Student's t test, ^*** P < 0.001, n/N = 18/2. In the experiment shown in A, further addition of 1 μm veratridine (V) to increase Na⁺ influx results in aberrant Ca²⁺ release and pooled data from these experiments (C) shows no increase in Ca²⁺ transient amplitude, n/N = 17/2. The time between the second two traces is 2 min.