Figure 4

Receptor-operated Ca²⁺ entry (ROCE) induced by application of endothelin-1 (Et-1) in TRPC1/6- (TRPC1/6^−/−) (a,c), STIM1/2− (STIM1/2^ΔpmLF) (b,c) and STIM1/2−TRPC1/6− (TRPC1/6^−/− STIM1/2^ΔpmLF) deficient primary murine lung fibroblasts (pmLF) (a,c). Wild-type pmLF infected with recombinant lentiviruses expressing Cre recombinase (Wt Cre) served as controls. Fura-2-loaded pmLF were stimulated with 4 µM Et-1 in Ca²⁺ containing buffer to generate ROCE. Intracellular Ca²⁺ levels ([Ca²⁺]_i) were quantified by analysis of fluorescence ratios at excitation wavelengths of 340 and 380 nm (ratio 340/380 nm) and normalized to initial values. Lines represent calculated means and light grey areas indicate standard error of the mean (SEM) of more than three independent experiments of at least three mice. Calculation of the areas under the curves (AUC) in Fig. 4a,b was used to quantify ROCE (c). One single dot represents the mean of at least 20 cells from one cell isolation. Asterisks mark significant differences from left to right (n > 3 mice, **P < 0.01, ***P < 0.001, ****P < 0.0001) between ratios of deficient cells compared to control cells.