Cerebrospinal fluid sampling by lumbar puncture in rats - repeated measurements of nitric oxide metabolites.

The ability to measure nitric oxide (NO) metabolites (NO2- plus NO3-: NOx) in cerebrospinal fluid (CSF) will facilitate understanding the involvement of NO in neurogenic or inflammatory diseases. The purposes of this study were to develop a reliable method for CSF sampling from the lumbar region, and to repeatedly measure NOx in naive rats. NOx in CSF were measured using the Griess method. Twelve young (13-week-old) and seven middle-aged (40-week-old) male Wistar rats were used. CSF (50-70 microl) was collected four times at 1-week intervals. The success rate of CSF collection was 96% and average surgery time was 21 min. The blood contamination rate was 11% on macroscopic inspection. NOx in the CSF ranged from 3.8 to 10.6 microM. The NOx in clear CSF were not significantly different from those with blood contamination on macroscopic inspection. There was, however, a linear correlation between the increase in NOx and the volume of venous blood added experimentally. NOx levels were significantly higher (P < 0.05) in young rats (6.5+/-0.2 microM) than in middle-aged rats (5.6+/-0.3 microM). There was no significant difference in CSF NOx among the four samples collected at 1-week intervals in 13-week-old rats. These results indicate that our CSF sampling technique can be used to reliably obtain a small amount of CSF for NOx measurement. This technique will facilitate further experimental studies of the involvement of CSF NO in neurogenic or inflammatory diseases.