TIME-DEPENDENCE OF PLASMA MALONDIALDEHYDE, OXYPURINES, AND NUCLEOSIDES DURING INCOMPLETE CEREBRAL-ISCHEMIA IN THE RAT

Incomplete cerebral ischemia (30 min) was induced in the rat by bilate rally clamping the common carotid arteries. Peripheral venous blood sa mples were withdrawn from the femoral vein four times (once every 5 mi n) before ischemia (0 time) and 5, 15, and 30 min after ischemia. Plas ma extracts were analyzed by a highly sensitive high-performance liqui d chromatographic method for the direct determination of malondialdehy de, oxypurines, and nucleosides. During ischemia, a time-dependent inc rease of plasma oxypurines and nucleosides was observed. Plasma malond ialdehyde, which was present in minimal amount at zero time (0.058 mu mol/liter plasma; SD 0.015), increased after 5 min of ischemia, result ing in a fivefold increase after 30 min of carotid occlusion (0.298 mu mol/liter plasma; SD 0.078). Increased plasma malondialdehyde was als o recorded in two other groups of animals subjected to the same experi mental model, one receiving 20 mg/kg b.w. of the cyclooxygenase inhibi tor acetylsalicylate intravenously immediately before ischemia, the ot her receiving 650 mu g/kg b.w. of the hypotensive drug nitroprusside a t a flow rate of 103 mu l/min intravenously during ischemia, although in this latter group malondialdehyde was significantly higher. The pre sent data indicate that the determination of malondialdehyde, oxypurin es, and nucleosides in peripheral blood, may be used to monitor the me tabolic alterations of tissues occurring during ischemic phenomena. In addition, these results suggest that the experimental model adopted i n the present study induces an incomplete brain ischemia in the rat re sponsible for the plasma variations of malondialdehyde, oxypurines, an d nucleosides, which mainly reflect the consequence of an oxygen radic al-mediated tissue injury and an alteration of energy metabolism. (C) 1994 Academic Press, Inc.