In order to study the permeability surface area product (PS), [51Cr]-EDTA was injected as a bolus dose (370 bq) followed by continuous infusion 0.33 ml/h (3.7 MBq/ml). To correct for tissue plasma volume, a bolus dose of [125I]-albumin was injected 3 min before the experiment was terminated and tissue collected. The plasma content, which is used to correct the [51Cr]-EDTA data (Table 2), was significantly higher 2 h after CFA treatment in PAG and cerebellum. 48 h after CFA treatment the plasma content was significantly higher in the spinal trigeminal nucleus. For IS a small increase was observed in the cerebellum at 24 h and with a minor change in the TNC. This increased plasma content suggests a larger blood volume that was increased due to the inflammation.
Table 2 Plasma volume in tissue in analyzed brain structures. Plasma volume in analyzed structures following application of CFA or IS to the dura was compared to plasma volume in analyzed structure following application of vehicle
Control CFA 2 h CFA 24 h CFA 48 h IS 2 h IS 24 h
Cortex (μL/mg) 7.3 + 0.6 12.2 ± 2.5 12.6 ± 0.8* 14.6 + 3.0* 11.3 ± 0.7* 11.0 ± 2.0
PAG (μL/mg) 6.0 ± 0.6 15.3 ± 3.2* 12.8 ± 1.4* 8.8 ± 1.5 13.8 ± 2.9 11.8 ± 2.3
Cerebellum (μL/mg) 9.5 ± 0.4 14.2 ± 0.8* 12.8 ± 0.5 29.4 ± 6.2 * 13.8 ± 1.7 16.3 ± 1.3*
L Spinal Trigeminal nucleus (μL/mg) 10.3 ± 1.7 14.3 ± 2.3 21.2 ± 2.1* 44.0 ± 14.4* 12.5 ± 3.5* 27.0 ± 8.9
R Spinal Trigeminal nucleus (μL/mg) 12.8 ± 2.6 13.7 ± 1.6 19.4 ± 1.8 23.6 ± 3.4* 16.0 ± 1.8 28.0 ± 11.0
L Trigeminal Ganglion (μL/mg) 52.3 ± 4.3 53.3 ± 12.5 48.0 ± 8.0 25.8 ± 3.1 40.5 ± 13.4 59.3 ± 10.3
R Trigeminal Ganglion (μL/min/g) 54.5 ± 5.7 51.7 ± 10.4 68.2 ± 13.9 22.0 ± 2.6 56.7 ± 15.5 83.8 ± 27.4
Differences in plasma volumes in tissue was found following application of both CFA and IS compared to vehicle (*p < 0.05)