Figure 6

Thapsigargin pretreatment specifically impairs the recovery of contraction during acetate exposure. (A) Representative recording of average sarcomere length assessed continuously throughout application and removal of normal Tyrode solution (NT) supplemented with 10 mM sodium acetate in cells pretreated with thapsigargin (1 μM) for 2–5 minutes. As expected, cell relaxation was markedly slowed so contractions were evoked at 0.5 Hz. (B & C) Summary data from experiments as in A (n = 9). Thapsigargin pretreatment had no effect on the acetate induced decrease in fractional shortening or increase in diastolic sarcomere length, but markedly blunted the recovery of contraction typically observed from 2–10 minutes during acetate application.