A model for chronic study of vascular morphology and reactivity of physically intact rat skin microcirculation

A non-invasive, non-traumatic model has been developed for long term study of the vascular anatomy, blood cell velocity and vascular reactivity of the cutaneous microcirculation of the rat. In the anesthetized rat, the hairless area of a toe close to the nail could be visualized by intravital video microscopy without manipulation of the skin. Good image quality of the vascular bed was obtained with the use of an incident illuminator equipped with a 50% mirror at 45 degrees to the optical axis and a polarizer-analyzer system in combination with a mercury lamp. This microscope system allows for visualization of the superficial vasculature of the skin, while microvessels can be repeatedly identified for several weeks. To test for vascular reactivity off-line analysis of blood cell velocity was performed in the control situation and during reactive hyperemia, using a video dual-window system and a cross-correlator. The mean control velocity in venules selected for testing of vascular reactivity was 70 micron/s. In these vessels a reproducible pattern of reactive hyperemia was seen with a mean peak velocity of 655 micron/s following arterial occlusion of 180 s. Possible applications of the model are discussed.