Effects of gadolinium on cardiac mechanosensitivity in whole isolated swine hearts

Figures

• 

  Figure 1. Mechanical stimulation protocol. (a) Dimensions of mechanical stimulation device. i, impact head (dimensions in mm). ii, markers for spring compression. iii, piston body (partial). iv, locking screw. v, spring. (b) Example of computer-controlled piston motion for delivering a mechanical stimulus. Bold bar indicates the timing of trigger signal for mechanical stimulation. Fine lines indicate piston movement. (c) Experimental protocol for delivering mechanical stimuli and electrical pacing. Gray bars indicate electrical pacing pulses and black bars indicate mechanical stimuli.

• 

  Figure 2. Example unipolar electrogram and electrical/mechanical stimulation trigger signals from a stimulation protocol. (a) The 1st, 2nd and 4th mechanical stimuli successfully elicited electrical activation; the 3rd mechanical stimulus failed. (b) A localized view of the signals near 4th mechanical stimulus in (a) shows the delay (D) between mechanical stimulation onset and electrical activation.

• 

  Figure 3. Effects of Gd3+ on mechanical stimulation success rate (R) and stimulation-activation delay (D) with recirculated perfusate. For each concentration level, R and D in the baseline condition (i.e. concentration = 0) were subtracted from R and D and the change averaged over animals is displayed. Error bars are standard deviations.

• 

  Figure 4. Effects of Gd3+ on mechanical stimulation success rate (R) and stimulation-activation delay (D) with non-recirculated perfusate. As in Fig. 3, change from baseline averaged over animals is displayed. Error bars are standard deviations.