NA-K ACTIVATED ADENOSINE TRIPHOSPHATASE FORMATION OF CEREBROSPINAL FLUID IN THE CAT

Digitalis-sensitive Na-K activated ATPase (Na-K ATPase), implicated in active cation transport, was shown to occur in cat choroid plexus. Cerebrospinal fluid (CSF) formation rate, measured by collection from cat cerebral aqueduct was inhibited 18% by intravenous desacetyl lanatoside C (0.2 mg/kg). Ouabain, placed intraventricularly, caused inhibition of flow, ranging from 100% by 10–5 mole to 0% by 5 x 10–10 mole. After 10–6 mole ouabain, Na-K ATPase activity in lateral ventricle choroid plexus was inhibited 69% without change in digitalis-insensitive, Mg activated ATPase and carbonic anhydrase activities. Ventriculocisternal perfusion with varying concentrations of ouabain, scillaren A, and hexahydroscillaren A gave CSF flow inhibition (inulin dilution technique) correlating quantitatively with in vitro Na-K ATPase inhibition. Other compounds studied were erythrophleine, cassaine, and l-norepinephrine. It is concluded that the choroid plexus Na-K ATPase system has a primary function in the formation of CSF in the cat, presumably through the active secretion of Na ions into the ventricle.

PATHOLOGIC FEATURES OF THE CHOROID PLEXUS. 1. CYTOCHEMICAL EFFECTS OF HYPERVITAMINOSIS A

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SECRETION OF CEREBROSPINAL FLUID BY CHOROID PLEXUS OF THE RABBIT

Blood flow in the principal draining vein of the choroid plexus of the lateral ventricle of the rabbit, which drains approximately the anterior 70% of the plexus, was measured by the analysis of motion pictures made during the injection of spheruler of 1-octanol. The relative loss of volume from the plasma compartment during the transit of blood was measured by the comparison of relative cell volumes in aortic blood and in venous blood of the plexus. The blood flow of the plexus averaged 2.86 µl/mg min and the rate of production of cerebrospinal fluid .37 µl/mg min. The effect upon the relative rate of production of fluid of several inhibitors was tested and of these acetazolamide was effective both intravascularly and topically; cardiac glycosides were effective topically, but not when given intravenously; and cyanide and 2,4-dinitrophenol were ineffective topically.