Quantitative determination of hydrolysis products of phospholipids in the ischaemic rat brain.

Abstract

1. Glycerylphosphoryl-and phosphoryl derivatives of choline, ethanolamine, serine and inositol, as well as glycerol were determined in rat brain following various periods of ischaemia. The phosphate esters were separated by twodimensional thin-layer chromatography and quantitated by phosphate determination. Free glycerol was analysed enzymatically. 2. The concentrations of phosphate esters ranging between 0.016 and 0.087 μmoles/g wet wt. in normal brain tissue, increased to levels of 0.189 to 0.327 μmoles/g wet wt. after 1 h of ischaemia. 3. Glycerol, undetectable in normal brain, reached a concentration of 1.3 μmoles/g wet wt. after 1 h; glycerol formation slowed down within the second hour, and from 2–8 h steadily rose to 5.4 μmoles/g wet wt. 4. Based on the amount of intermediates and glycerol formed the rate of phospholipid catabolism during ischaemia at normothermia was calculated. The metabolites indicated hydrolysis of phospholipids via two pathways catalysed either by phospholipases A1 and A2 (EC. 3.1.4.2), or by phospholipase C (EC 3.1.4.3) cerophosphoryl choline diesterase (EC 3.1.4.2), or by phospholipase C (EC 3.1.4.3) and tissue lipases (EC 3.1.1.3).