NEW MODEL FOR IN-VIVO OBSERVATION OF THE FELINE SPINAL MICROCIRCULATION - THE CLOSED SPINAL WINDOW

A NEW EXPERIMENTAL model is described that uniquely allows the in vivo observation and quantification of vascular caliber changes on the dor sal surface of the feline spinal cord. The model consists of a rectang ular Plexiglas window that is sutured to the lumbar dura and is suppor ted by a special holder. Inlet and outlet tubes attached to the window serve for topical applications of mock cerebrospinal fluid or vasoact ive agents to the surface of the cord and for continuous monitoring of intrathecal pressure. Pial vessels below the window were observed at 200-fold magnification with the aid of a microvideo camera. Spinal art erioles reacted to hypercarbia and superfusion with acetylcholine solu tion in a manner similar to cerebral arterioles. Tests with increased intrathecal pressure showed that the window remained watertight betwee n 25 and 130 mm Hg, with an average leakage pressure of 57.8 +/- 33.5 mm Hg. To promote the use of this model in other laboratories, the aut hors give a detailed description of the closed spinal window preparati on and report their experiences gained from 50 experiments. It is conc luded that the closed spinal window is a highly reproducible model, su itable for the study of the feline spinal microcirculation for several hours in vivo.