MORPHOLOGY OF ASTROGLIA IN COLONY CULTURES FOLLOWING TRANSIENT EXPOSURE TO POTASSIUM-ION, HYPOOSMOLARITY AND VASOPRESSIN

Brain swelling is the major cause of delayed neuronal damage following injury to the central nervous system. Swelling of mouse astroglial cells was studied in colony cultures by light and electron microscopy. Swelling of suspended astroglial cells was studied by flow cytometry. Swelling caused by hypoosmolar solution was more pronounced than that caused by 15 or 60 mM K+. Under both conditions swelling in both immature and mature astroglia was followed by a regulatory volume decrease. Arginine vasopressin caused mild astroglial swelling and atrial natriuretic peptide did not significantly affect cell volume. All changes in extracellular environment were associated with changes in the morphology of microvilli and varying amounts of membrane ruffling. Immature cells exhibited a delayed response to the application of atrial natriuretic peptide and less membrane ruffling following exposure to 60 mM K+ than mature astroglia. These nonspecific morphological changes are likely associated with changes in membrane ion pump activity.