Skin capillary reperfusion after regional ischemia.

Capillary reperfusion following four hours of regional ischemia was determined in the ear skin microvasculature of 10 homozygous hairless mice. Selective arteriolar ligation was used to produce flow stasis in capillaries within an ischemic risk zone (RSK) without direct compression of the microvasculature under study. Reperfusion capillary RBC velocities (CBV), diameters, and flow times in both RSK and nonischemic capillaries (NRSK) were measured and compared to baseline values after flow stasis was verified in the RSK capillaries. Baseline values of CBV, diameter and flow time did not differ between RSK and NRSK. In the RSK capillaries, the post-ischemic mean CBV was significantly less than baseline (120 +/- 22 vs. 212 +/- 31 microns/s, p less than 0.01), whereas in NRSK capillaries no differences were detected (195 +/- 41 vs. 174 +/- 22 microns/s). The decrease in mean CBV in RSK capillaries was mainly due to an increase in the number of capillaries with low or zero reflow. The percentage of capillaries having CBV less than 100 microns/s increased from 10% at baseline to 45% after ischemia. These results indicate that when capillary flow stasis is produced, durations of skin ischemia of four hours may subject the microvasculature to significant reperfusion deficits.