Analysis of contractile parameters in response to the pressure step protocol in IALVs from Ip3r1fl/fl and Ip3r1ismKO mice. (A–I) Statistical summary of contractile parameters (A) frequency across Ip3r1fl/fl and Ip3r1ismKO IALVs or within groups (B and C) contraction amplitude, (D) vessel tone across Ip3r1fl/fl and Ip3r1ismKO groups, (E) ejection fraction, (F) nAmp, (G) vessel tone compared across pressure within groups, (H) MaxD, and (I) fractional pump flow in at each tested pressure. n = 12 Ip3r1fl/fl and n = 12 Ip3r1ismKO IALVs with mean and SEM shown.