Metabolic aspects of acute cerebral hypoxia during extracorporeal circulation and their modification induced by acetyl-carnitine treatment.

Following their previous research experiences in human tissue hypoxia, in the present study the authors. investigated the metabolic effects of acute brain hypoxia in a group of patients in course of extracorporeal circulation for aorto-pulmonary bypass. One hundred subjects were treated, half with a placebo and half with acetyl-carnitine to evaluate the effects of oxidative stress in some brain plasmatic metabolites and to verify the effect of acetyl-carnitine on the tissue energy capacity. The levels of lactate, pyruvate, succinate and fumarate showed a significant imbalance due to hypoxia, while the acetyl-carnitine treatment confined the metabolic gradients within physiological limits. This means that during the course of extracorporeal circulation brain hypoxia plays a pathological role assuming the typical picture of cellular oxidative damage and the acetyl-carnitine antagonizes these deleterious effects of hypoxia by a protective mechanism on the energy processes and then on the cellular enzymic activities. In this regard, the d-tyrosine levels, considered as a proteolytic index, confirm the action of acetyl-carnitine on the cell morpho-functional integrity.

Metabolic aspects of acute tissue hypoxia during extracorporeal circulation and their modification induced by L-carnitine treatment.

In this study the authors examine the effects of acute hypoxia due to extracorporeal circulation (ECC) and the role played by L-carnitine treatment on some plasmatic metabolites linked to glycolytic cellular metabolism. To obtain biochemical data, 120 patients in extracorporeal circulation during aortopulmonary bypass surgery were evaluated. The patients received either sodium bicarbonate (40 patients), or L-carnitine during ECC (40 patients) or before and during ECC (40 patients), and plasma samples were collected before ECC, during ECC and after ECC. The levels of lactate and pyruvate showed significant alterations in sodium bicarbonate-treated patients, and there was also a considerable imbalance in the succinate/fumarate ratio. This means that tissue hypoxia due to ECC leads to cellular oxidative damage and to a considerable decrease in the intracellular energy pools. The use of L-carnitine antagonizes the oxidative stress, as is well documented by the levels of plasmatic metabolites which remain confined to normal amounts.