Abstract
1. The ability of several serum fractions to increase the cytosolic calcium concentration ([Ca2+]i) was tested in rat cerebellar cells maintained in primary culture. 2. Serum filtered through an ultrafiltration membrane with 3000 Da molecular mass cut-off (filtered serum, FS) selectively stimulated neurons whereas dialysed serum (DS) selectively stimulated glia. 3. The effects of FS were due to glutamate as they were reproduced by N-methyl-D-aspartate (NMDA), blocked by NMDA receptor antagonists and prevented by enzymatic removal of glutamate. 4. The effects of DS on glia were not reproduced by platelet-activating factor, thrombin or bradykinin. They were not lost on heating or extraction with diethyl ether. They were reproduced by a methanol-chloroform-HCl extract from DS and by several commercial fraction V plasma albumins. 5. These [Ca2+]i-increasing factors present in blood could contribute to brain damage during ischaemia if they reached the brain interstitium on disruption of the blood-brain barrier.