Compared effects of extracellular K+ ions and soman, a neurotoxic, on cerebral astrocyte morphology. An in vitro study.
One of the roles of astrocytes in the maintenance of perineuronal ionic balance during intense neuronal activity occurring after injection of convulsant agents like soman. Soman is an irreversible cholinesterase inhibitor and induces brain damage with early swelling of astrocytic perivascular processes. Mature astrocytes are easily characterized on freeze-fracture replicas owing to the presence of regular geometric aggregates of intramembranous particles: the 'orthogonal arrays' (OAs). In primary cultures of astrocytes OA distribution is homogeneous throughout the plasma membrane. A present hypothesis (see review in Risau and Wolburg, 1990) considers that these OAs are associated with channels controlling potassium ion concentration in the cerebral parenchyma. We have investigated the effects of extracellular concentrations of K+ ions identical to those observed during neuronal activity on primary cultures of astrocytes and effects induced by soman. High concentrations of K+ ions (60 mM) as well as soman exerted direct effects on astrocytic plasma membranes: K+ ion influx within astrocytes induces a partial disaggregation of OAs and more acutely than soman. Neither K+ ions nor soman induce swelling of astrocytic end-feet.
Grange-Messent
V
V
Laboratory of Cytology, CNRS URA 1488, Paris VI University, France.
Raison
D
D
Bouchaud
C
C
D000818:Animals; D001253:Astrocytes / Q000187:drug effects* / Q000473:pathology / Q000648:ultrastructure*; D001921:Brain / Q000187:drug effects* / Q000473:pathology / Q000648:ultrastructure*; D002478:Cells, Cultured; D004487:Edema / Q000139:chemically induced / Q000473:pathology; D007150:Immunohistochemistry; D051379:Mice; D008807:Mice, Inbred BALB C; D018715:Microscopy, Video; D011188:Potassium / Q000633:toxicity*; D012999:Soman / Q000633:toxicity*
D012999:Soman; D011188:Potassium