[Blood flow, CO2 response and autoregulation in the rat spinal cord by laser-Doppler flowmetry and hydrogen clearance].

Spinal cord blood flow (SCBF) was measured simultaneously by laser Doppler flowmetry (LDF) and hydrogen clearance (HC) in the normal Wistar rats. Under normal physiological condition, SCBF values by HC was 45.0 +/- 1.7 ml/min/100 g at the level of Th-8. LDF values were well correlated (r = 0.78) to the SCBF measured by HC, where linear regression line was obtained as y = 14.2x - 1.58. Absolute SCBF values of LDF were also calculated as 43.7 +/- 1.3 mg/min/100 g using this equation. CO2 response of SCBF were 1.09 ml/min/100 g/mmHg by HC and 1.01 ml/min/100 g by LDF, respectively. Autoregulation of SCBF maintained at a range of 55 -155 mmHg of mean arterial pressure in both methods. In conclusion, LDF is a useful technique for continuous SCBF monitoring. Since absolute SCBF value in LDF has some variance, the relative value is more suitable for accurate evaluation of SCBF during time course of an experiment.