Microcirculatory measurements in the same conscious rats (WKY and SHR) during their first year from birth.

To study peripheral circulation, it is desirable to avoid anesthesia and surgical trauma to the experimental animal. The depilated auricle (external ear) of rat provides this as a model and is used to facilitate numerous analyses of age-related changes in hemodynamics in the same animal. The rat is placed in a plastic tube and the right auricle is positioned on a transparent block with electronically controlled temperature using intravital microscopic techniques (transmitted light). Red blood cell (RBC) velocities and capillary diameters (phi cap, column of blood) were measured in the course of 15 months from birth (flying spot technique, angiometer or ruler). Between week 13 to week 27 from birth, RBC-velocities increase significantly (p less than 0.01) to steady-state levels (WKY: 0.16 mm/s; SHR:0.19 mm/s); the velocities were higher in SHR than in WKY (about 20 to 25%). phi cap decrease from values of about 7.0 microns to 6.3 microns (p less than 0.05). RBC-velocities depend on ambient temperature and reach maximum values between 35 degrees C and 37 degrees C surface temperature.