Subarachnoid versus ventricular perfusion in the rabbit

Abstract

Summary (1)An artificial CSF was perfused either from both lateral ventricles, or from the interhemispheric subarachnoid space, to the cisterna magna of habbits. The perfusate was collected regularly during 2 h of intravenous infusion of Na 131 I, Na 131 I plus NaC1O 4 , 24 NaC1, thiourea, [ 3 H], [ 51 Cr]EDTA or RIHSA. The concentrations of these substances in the perfusion fluid and brain were compared to that of the average stable plasma concentration. (2) In general it was found that, with substances entering with difficulty into the ventriculo-cisternal perfusion fluid, such as 131 I-, [ 51 Cr]EDTA, and [ 3 H]PAH, penetration into the cortical subarachnoid perfusion fluid was very much more rapid. This difference did not extend to RIHSA, however, which was almost completely excluded from both perfusion fluids. (3)Penetration into the brain, from the blood, was not greatly affected by the mode of perfusion; and with subarachnoud perfusion the penetration into regions of cortex exposed to the perfusion was little different from penetrations into regions not so exposed. (4)It is suggested that the technique of subarachnoid perfusion employed in this work creates an artificial connextion between the subarachnoid and subdural spaces, so that the perfusion fluid enters into free diffusional relations with the dura, thus avoiding the barrier constituted by the arachnoid membrane.