CSF Absorption Rates in Cats with Kaolin-Induced Hydrocephalus — a Study Using Different Kinds of Tracers of Different Molecular Size

Summary

The absorption rate of CSF was studied in experimental hydrocephalus, using three kinds of tracers. Hydrocephalic cats were divided into three groups: (1) acute, (2) subacute, and (3) chronic. Five normal cats were used as controls. Three different kinds of radioisotope — tritiated water (³H), ¹⁴C labeled albumin (¹⁴C), and NaH₂PO₄ (³²P) — were used as tracers. Each tracer, dissolved in artificial CSF (MOS-4; SHIMIZU), was perfused between the lateral ventricles in each group. The perfusion pressure was increased stepwise by 5cmH₂O and 15cmH₂O before ligation of the spinal cord and was increased to 25cmH₂O after ligation. In normal cats the absorption rate of tritiated water was almost twice as much as that of ¹⁴C and ³²P before and after ligation of the spinal cord. Pressure dependency was noted. In acute hydrocephalus the absorption rate for all tracers was reduced to about 1/3 that in normal cats. In the subacute state, the absorption rate of tritiated water (³H) and electrolyte (³²P) gradually recovered. In the chronic state, the absorption rate of ¹⁴C-labeled albumin also increased before ligation of the spinal cord. After ligation the absorption rate was reduced but was still perceptible. These findings indicated that there may be different pathways for each tracer.