Abstract
The effect of dihydroergocristine on energy metabolism was studied in the isolated perfused rat brain affected by ischemia and in cultivated C-1300 neuroblastoma cells deprived of oxygen and glucose. Creatine phosphate, ATP, ADP, AMP, glucose, glucose-6-phosphate, fructose-6-phosphate, fructose-1,6-diphosphate, pyruvate, and lactate were measured enzymatically. After a perfusion period of 30 min, the cortex of the isolated perfused rat brain exhibited an energy state not different from that in vivo. Dihydroergocristine added to the perfusion medium (5 μmol/L) did not influence these substrate levels under normal perfusion conditions. However, this drug was able to retard the breakdown of high-energy phosphates during ischemia and to accelerate the restoration of the energy state during the postischemic reperfusion period. The perfusion rate was not changed by the drug, and therefore it was assumed that dihydroergocristine could act directly on cell metabolism. This view was supported by the results obtained from experiments using cultivated N-2a neuroblastoma cells. These cells were incubated in a buffered salt solution deprived of glucose and oxygen for 15 min. Under these conditions, dihydroergocristine (2 μmol/L) added to the incubation medium caused changes in the concentrations of the high-energy phosphates similar to those in the isolated brain preparation: It increased the ATP concentration and decreased the ADP concentration significantly.