Increased brain uptake and CSF clearance of 14C-glutamate in spontaneously hypertensive rats

Blood-to-brain and blood-to-CSF transport kinetics of C-14-glutamate in the spontaneously hypertensive rats (SHR) were studied using the in situ brain perfusion technique. Also, clearance of C-14-glutamate from CSF of SHR was studied using the ventriculo-cisternal (VC) perfusion technique. Blood-to-brain and blood-to-CSF transport kinetics showed greater rate of maximal transport into both brain and CSF of SHR compared to nonnotensive Wistar Kyoto (WKY) rats (p>0.05). Uptake into CSF of WKY and uptakes into brains of WKY and SHR did not show any significant diffusion (K-d) of C-14-glutamate (p < 0.05). However, some diffusion of C-14-glutamate only into CSF of SHR was observed, 0.031 + 0.006 mu l min(-1) g(-1). Clearance of C-14-glutamate from CSF was greater in the SHR (28.33 +/- 6.9 mu l min(-1)) compared to that in WKY rats (19.42 +/- 4.7 mu l min(-1)). However, C-14-glutamate uptake by brain from CSF side was not significantly different between SHR and WKY rats (p>0.05). These results suggest that the greater blood-to-brain and blood-to-CSF entry of C-14-glutamate during hypertension may be balanced by greater removal of C-14-glutamate from CSF back to blood. (C) 2003 Elsevier B.V. All rights reserved.