Aldosterone affects vascular tone during ischemia reperfusion injury in hamster cheek pouch

The present study aimed to assess the effects of topically appliedaldosterone [ALD] on vascular tone during ischemia reperfusion injury in the hamster cheek pouch microcirculation. Male Syrian hamsters were anesthetized with pentobarbital [5 mg/100 g body wt, i.p.], tracheotomized and intubated. They were submitted to 30 min of ischemia and 30 min of reperfusion. Cheek pouch microvessels were visualized by fluorescence microscopy using fluorescent dextran [MW 150 kD] as a tracer. Diameter of vessels, perfused capillary length, microvascular permeability, expressed as Normalized Grey Level [NGL], and leukocyte adhesion were determined by computerized methods.Under baseline conditions, ALD [0.2- 0.5 –2.4 mM/L/2 min] induced dose-dependent constriction of all arterioles within 2.0 ± 0.5 min of administration. These vessel size-related effects were prominent in A4 arterioles [diameter: 8.7 ± 0.9 μm] that constricted by 24 ± 3% of baseline [at the highest dose]. ALD, 2.4 mM/2 min, applied before ischemia and at reperfusion, caused arteriolar constriction resulting in marked decrease in perfused capillary and postcapillary venule length [–70± 3 % of baseline], significant compared to control [p<0.05]. Therewas patchy increase in leakage [NGL=0.70± 0.03, p<0.01 vs. baseline], differently distributed compared to control, and reduced adhesion of leucocytes [4 ± 2 vs. 9 ± 2/100 μm venular length, p<0.01 vs. control]. In conclusion, our data suggest that ALD induces constriction of arterioles with marked decrease in tissue perfusion and patchy increase in leakage during ischemia reperfusion injury.