Effects of soman on cerebral astrocyte plasma membranes: a freeze-fracture study

Astrocytes are identifiable on freeze-fracture by regular geometric aggregates of uniform intramembranous particles (IMP), the 'orthogonal arrays' (OA). These OAs are considered to be potassium channels that maintain the ionic balance around neurons. After subcutaneous administration of a single near LD50-dose of soman in rats, neurotoxic epileptogenic irreversible cholinesterase inhibitor, replicas showed a significant decrease in OA density in the convulsed animals. This dissociation by soman confirms that OA are a particularly labile membranes specialization. Frequent clumping of IMP and numerous cleavage planes were observed; this could be the result of an interaction between the liposoluble poison and membrane phospholipid fluidity.