Abstract
A number of drugs used in the pharmacotherapy of cerebral metabolic and vascular disease have been studied for their effects on the respiration of mitochondria isolated from the rat brain. Some of these agents increased the respiratory control ratio by more than 5% from base-line values (at p < 0.05), namely, aminophylline, dihydroergotoxine, ifenprodil, nicergoline, raubasine, and vincamine. The ability of these agents to increase the efficiency of mitochondrial respiration could be correlated with two other attributes peculiar to these five drugs: their ability to contract cerebrovascular smooth muscle when studied in vitro and their ability to decrease the volume of infarcted brain tissue following experimental occlusion of the middle cerebral artery in the cat. Papaverine and its derivatives (naftidrofuryl, viquidil, YC-93) decreased respiratory control, an effect that might correlate with their capacity to effect a vasodilatation of the cerebral vessels and their inefficacy in models of acute cerebral infarction. There is a considerable body of evidence suggesting that one of the earliest and most fundamental perturbations of cerebral ischaemia is a loss of respiratory control. Ifenprodil, vincamine, and some related “anti-ischaemic” compounds are capable of increasing respiratory control in normal cerebral mitochondria, and this capacity might well help to explain their therapeutic potential in cerebrovascular disorders in which energy supply to the brain is limited.