Figure 7. Frailty and age have no effect on either fractional SR Ca²⁺ release or SR Ca²⁺ content.

A, representative examples of caffeine‐induced Ca²⁺ transients recorded from myocytes isolated from mice with different FI scores. B and D, SR Ca²⁺ content was similar in myocytes from the adult and aged groups and showed no obvious relationship with FI score. C and E, fractional SR Ca²⁺ release was not affected by either age or frailty. Differences between age groups were assessed using a t test and Mann–Whitney Rank Sum test and linear regression analysis was used to evaluate the impact of FI score (n = 6 adult and 11 aged myocytes). Filled symbols indicate adult mice and open symbols indicate aged mice.