Effect of severe incomplete ischaemia and postischaemic reperfusion on phospholipids and unesterified cholesterol in rabbit spinal cord.

Effect of severe incomplete ischemia, induced by occlusion of the abdominal aorta caudal to the left renal artery for 40 min, and postischemic reperfusion for 6 h, 1 and 4 days on phospholipid composition and unesterified cholesterol concentration was studied in the lumbosacral (L3-S1) spinal cord separated into the gracile fascicle (Fg), dorsal part without Fg (Dp) and ventral part (Vp). Ischemia decreased the inositol phospholipid (PI) concentration in Dp and Vp and this was recovered during reperfusion. Within 6 h following ischemia, ethanolamine (PE) and serine (PS) phospholipid concentrations decreased in Dp and PS also in Vp. During the long reperfusion intervals the concentrations of the two major phospholipids, PE and choline phospholipid (PC) declined in Fg, Dp and Vp. No changes were observed in sphingomyelin (SM). The concentration of unesterified cholesterol (UC) was lower throughout the reperfusion period in Dp and Vp, while the decrease in Fg was delayed. The molar ratio UC/TPL was reduced starting from 24 h of reperfusion. The pattern of changes, which were delayed in the white matter as compared to Dp and Vp (containing the gray matter) indicated severe damage to the membrane structures in the tissue, developed during reoxygenation, that was related to decreased tissue viability.