__Figure 4__ Relationship
between size of the region at risk and size of myocardial
infarction. The figure illustrates both individual values
and the regression lines obtained by linear regression analysis
for the various groups. __Left panel__. Control
groups: groups I (4-h reperfusion) and II (24-h reperfusion). __Middle
panel.__ Studies of early PC: groups III (early PC sham
group, 24-h reperfusion) and IV (early PC group, 24-h reperfusion). __Right panel__.
Studies of late PC:
groups V (late PC sham group, 4-h reperfusion), VI (late PC
group, 4-h reperfusion), VII (late PC sham group, 24-h
reperfusion), and VIII (late PC group, 24-h reperfusion).
In all groups, infarct size was positively and linearly related
to risk region size. The linear regression equations were
as follows: group I, y= -2.55+0.57x, r=0.87, P<0.005; group
II, y= -2.3+0.59x, r=0.77, P<0.001; group III, y= -1.29+0.59x,
r=0.85, P<0.001; group IV, y= -8.34+0.31x, r=0.77, P<0.005;
group V, y= -9.11+0.71x, r=0.87, P<0.001; group VI, y= -0.41+0.23x,
r=0.64, P<0.05; group VII, y= -1.05 +0.53x, r=0.91, P=0.01;
group VIII, y=9.01+0.05x, r=0.16, P=0.60. ANCOVA
demonstrated that the regression line for group IV was
significantly different from that for group III and that the
regression lines for groups VI and VIII were significantly
different from those for groups V and VII, respectively (P<0.05
for each comparison), indicating that for any given risk region
size, infarct size was smaller in preconditioned mice compared to
control mice. Reproduced from Ref. 2 with permission.