Age and site variability of skin blood perfusion in the hairless mouse ear determined by laser Doppler flowmetry.

Laser Doppler Flowmetry (LDF) was used to characterize skin blood perfusion variations present within the Homozygous Hairless mouse ear microvasculature as a function of 1) arteriolar level within the microvasculature, 2) animal age and 3) LDF probe distance above the tissue being studied. To this end blood perfusion measurements (arbitrary perfusion units) were made in the ear at vascular sites in the vicinity of primary vessels (site A), secondary vessels (site B), tertiary vessels (site C), and peripheral zones distant from larger vessels. These were done without any invasive procedures save anesthesia administration and were carried out at three different tissue-probe distances (0.5, 0.75 and 1.0 mm) on three groups of eight mice each with ages of three, five and eight weeks. Results show a significant gradient in perfusion from sites A to D in each age group and a significant increase in perfusion with increasing age. The effect of probe-tissue distance variations on perfusion values was found to be significant between 0.5 mm and 1.0 mm but overall differences were small. In addition to these specific findings the present results demonstrate the potential of LDF as a means of detecting, evaluating and correlating perfusion changes, either by itself or as a complementary method to detailed microvascular measurements using conventional in vivo microscopy.