Measurement of cerebrospinal fluid pressure in conscious rats

We describe a method of using a micro-tip transducer to measure cerebrospinal fluid pressure (CSFp) through a lateral ventricular cannula in unanesthetized, restrained, non-stressed rats. The mean value of CSFp under the anesthesia was 4.2 +/- 0.9 (mean +/- SEM, n = 6), ranging from 1.3 to 7.5 mmHg. Measurements were made daily in conscious state for 7 consecutive days after the operation. Mean value of CSFp was 9.1 +/- 0.5 mmHg (n = 42), ranging between 8.0 +/- 1.4 and 10.4 +/- 1.3 mmHg (n = 6) from day to day (P > 0.05). The permanent intraventricular cannula did not cause any detectable changes in behavior, arterial pressure, arterial blood gas, arterial blood acid-base chemistry, and water content of the punctured hemisphere. The results indicated that the method is a reliable alternative for CSFp measurement in a conscious, restrained, non-stressed rat which can be used under a variety of experimental conditions.