(see article)-activated ATPase and K-+-activated rho-nitrophenyl-phosphatase activities of the nervous system cells in tissue culture

Morphological changes in the cat cerebral cortex produced by superfusion of ouabain

The morphological changes following superfusion of the cat cerebral cortex with ouabain were studied. Autoradiography of [3H]ouabain was performed to study drug distribution. The resulting lesion consists of an upper vacuolated layer which is distinctly separated from an underlying region containing dark neurones. Ouabain is confined to the vacuolated layer. Swelling of apical dendrites and many presynaptic terminals are the main morphological changes occurring in the vacuolar layer. Depletion of synaptic vesicles, clustering of vesicles around the synaptic membrane, and the production of coated vesicles and cisternae are further changes found within presynaptic endings. Whilst swelling of fibrous astrocytes within the glialimitans occurs, this is not true of astrocytic processes elsewhere in ouabain exposed regions. Regions containing dark neurones are characterised by a general swelling of astroglial processes. The results strongly suggest that apical dendrites and presynaptic endings possess high activities of Na+, K+-ATPase whereas the activity on astroglial processes within the neuropil is relatively low. Astroglial swelling in areas of dark neurones is produced by some change in the chemical milieu surrounding the processes which appears unrelated to Na+, K+-ATPase inhibition.

Contact-mediated changes in ATPase activity at the surface of primary cultured hepatoma cells

Hepatoma cells grown in monolayer culture display certain alterations in their Mg-ATPase activity present on the cell surface as a function of time during a exponential growth. Levels of enzyme estimated biochemically and expressed as activity per cell increase as the cell population density increases. Histochemical investigation shows that Mg-ATPase activity is located intensively on the surface of cell contact and the activity is not encountered on the cell surface facing the free space. No enzyme activity is detected histochemically on the cell surface of sparse culture. Deposits of acidic polysaccharide are also seen on the surface of cell contact.

The chronic and acute effects of ethanol on adenosine triphosphatase activity in cultured astroblast and neuroblastoma cells

Mg2+ATPase and (Na+ + K+)ATPase activities were measured in clonal line NN hamster astroblasts and in clonal lines M1 and N1E-115 mouse neuroblastoma cells after the cells had been subjected to the acute and chronic actions of 100 mM ethanol. Exposure of the astroblasts to ethanol for periods as long as 68 days produced an increase in total cellular Mg2+ ATPase activity, as measured in cell homogenates; however, activity reverted to control levels upon withdrawal of ethanol. Chronic exposure of clonal line N1E-115 neuroblastoma cells to ethanol produced an increase in Mg2+ATPase and (Na+ +K+)ATPase activities. In contrast, the activities of both ATPases of clonal line M1 neuroblasts were unaffected by chronic exposure to ethanol. Acute exposure of cell homogenates to 100 mM ethanol inhibited Mg2+ ATPase and (Na+ + K+)ATPase of astroblasts but not that of neublastoma cells. These findings suggest that neural cells in culture may serve as useful models for studying the effects of ethanol on specific cell types.