Fig. 6.

PC2 modulates the kinetics of Ca²⁺ transient from RyR2. (a) Representative traces of Ca²⁺ transient in Pkd2^+/+ and Pkd2^−/− cardiomyocytes. Cardiomyocytes were loaded with fluo-4, and Ca²⁺ transients were then elicited by 20 mM caffeine in the absence of extracellular Ca²⁺. (b) Comparison of the Ca²⁺ transient. Shown are F/F₀ in Pkd2^+/+ (n = 32) and Pkd2^−/− (n = 40) cardiomyocytes. Statistical significance was calculated by using a one-tailed t test: ∗∗, P < 0.001. (c) Rate of rise of Ca²⁺ transient in Pkd2^+/+ and Pkd2^−/− cardiomyocytes. Pkd2^−/− cardiomyocytes have significantly decreased peak in fluorescence compared with Pkd2^+/+ cardiomyocytes: ∗∗, P = 0.001 (one-tailed t test). (d) Duration of Ca²⁺ transient in Pkd2^+/+ and Pkd2^−/− cardiomyocytes. Pkd2^−/− cardiomyocytes had a significantly longer duration of Ca²⁺ transients compared with Pkd2^+/+. Statistical significance was calculated by using a one-tailed t test: ∗∗, P < 0.001 (number of experiments for each genotype: 35).