Figure 2.

Calcineurin inhibitory peptide (CIP) attenuates store-operated calcium (SOC) entry and decreases I_SOC in pulmonary artery endothelial cells (PAECs). A, PAECs were loaded with Fura 2/AM (fura 2-acetoxymethyl ester) and pretreated with 50 μM CIP or vehicle alone for 1 hour, and changes in intracellular [Ca²⁺] were measured. SOC entry was revealed by thapsigargin treatment in low-Ca²⁺ buffer. Upon 2 mM Ca²⁺ add-back, CIP-treated PAECs exhibited a decreased SOC (red tracing) compared to controls (black tracing). Each tracing represents mean ± SEM of at least 4 experiments with 2 regions of interest of 10–20 cells for each. B, Single cells were pretreated with CIP for 1–2 hours and examined in a whole-cell patch-clamp configuration with CIP added to the patch pipette. The I_SOC channel was activated by thapsigargin in the patch pipette. Cells were held at 0 mV and stepped from −100 to +100 mV for 200 milliseconds. CIP treatment attenuated I_SOC at all negative testing potentials, as compared to control cells. Asterisk indicates significant differences from control cells.