OBJECTIVE: Ischemic preconditioning and some
drugs can protect
tissues from
injury by preserving
microcirculation . This study evaluated
vascular permeability in a
hamster cheek pouch preparation using either short ischemic periods or
bradykinin as preconditioning stimuli followed by 30 min of
ischemia /
reperfusion .
METHOD: Sixty-six
male hamsters were divided into 11 groups five combinations of different ischemic frequencies and durations (one, three or five shorts periods of
ischemia ,
separated by one or five minutes) with 10 min intervals between the ischemic periods, followed by 30 min
ischemia /
reperfusion ; three or five 1 min ischemic periods with 10 min intervals between them followed by the topical application of
histamine (2 µM);
bradykinin (400 nM) followed by 30 min of
ischemia /
reperfusion ; and three
control groups (30 min of
ischemia /
reperfusion or
histamine or
bradykinin by themselves). Macromolecular
permeability was assessed by
injection of
fluorescein -labeled
dextran (
FITC -
dextran , MW= 150 kDa; 250 mg/Kg
body weight ), and the number of leaks/cm2 was counted using an intravital microscope and fluorescent
light in the
cheek pouch.
RESULTS: Plasma leakage (number of leaks/cm²) was significantly reduced by preconditioning with three and five 1 min ischemic periods, one and three 5 min ischemic periods and by
bradykinin .
Histamine -induced macromolecular
permeability was also reduced after three periods of 5 min of
ischemia .
CONCLUSION: Short ischemic periods and
bradykinin can function as preconditioning stimuli of the
ischemia /
reperfusion response in the
hamster cheek pouch
microcirculation . Short ischemic periods also reduced histamineinduced macromolecular
permeability .