Renal and systemic acid-base effects of chronic dichloroacetate administration in dogs

A Review of the Role of Blood Lactate Measurements in the ICU

The production of hyperlactatemia in the critically ill patient has previously been thought to be primarily related to anaerobic conditions. Newer data suggests that lactate accumulates under aerobic conditions in clinical settings that were previously thought to solely represent anaerobic processes. This review summarizes the present understanding of lactate metabolism and reviews the data supporting use of lactate determinations in the critical care setting. The use of lactate as a marker of inadequate tissue perfusion as well as its role as a prognostic indicator are discussed. The utility of managing lactic acidosis with various buffers is also reviewed.

The pharmacology of dichloroacetate

Dichloroacetate (DCA) exerts multiple effects on pathways of intermediary metabolism. It stimulates peripheral glucose utilization and inhibits gluconeogeneis, thereby reducing hyperglycemia in animals and humans with diabetes mellitus. It inhibits lipogenesis and cholesterolgenesis, thereby decreasing circulating lipid and lipoprotein levels in short-term studies in patients with acquired or hereditary disorders of lipoprotein metabolism. By stimulating the activity of pyruvate dehydrogenase, DCA facilitates oxidation of lactate and decreases morbidity in acquired and congenital forms of lactic acidosis. The drug improves cardiac output and left ventricular mechanical efficiency under conditions of myocardial ischemia or failure, probably by facilitating myocardial metabolism of carbohydrate and lactate as opposed to fat. DCA may also enhance regional lactate removal and restoration of brain function in experimental states of cerebral ischemia. DCA appears to inhibit its own metabolism, which may influence the duration of its pharmacologic actions and lead to toxicity. DCA can cause a reversible peripheral neuropathy that may be related to thiamine deficiency and may be ameliorated or prevented with thiamine supplementation. Other toxic effects of DCA may be species-specific and reflect marked interspecies variation in pharmacokinetics. Despite its potential toxicity and limited clinical experience, DCA and its derivatives may prove to be useful in probing regulatory aspects of intermediary metabolism and in the acute or chronic treatment of several metabolic disorders.

Comparative metabolic effects of acetate and dichloroacetate infusion in the anesthetized dog

The comparative effects of acetate (10 mmol/h/kg) and dichloroacetate (DCA) (1 mmol/h/kg and 10 mmol/h/kg) on acid-base and intermediary metabolism were assessed using the fasted anesthetized dog, undergoing controlled ventilation, as a metabolic model. Infusion of acetate resulted in a marked metabolic alkalemia and a decline in PaO2, while DCA had minimal effects on acid-base state and oxygen consumption. Serum glucose decreased with both DCA and acetate infusion, although only significantly with the latter. At infusion rates of 10 mmol/h/kg, acetate caused marked decreases, while DCA caused marked increases, in serum potassium and phosphorus. Acetate and DCA also had opposing effects on lactate and citrate levels, the former caused increases and the latter decreases in both metabolites. Pyruvate levels decreased similarly in response to both infusates. Acetoacetate and beta-hydroxybutyrate levels increased significantly with both acetate and DCA infusions; however, the increases were much greater with acetate than with DCA infusion. Blood alanine levels decreased significantly during the infusion of both acetate and DCA, whereas, free fatty acids tended to increase with acetate infusion, remained unchanged with low dose DCA and fell significantly with high dose DCA. Plasma insulin levels were sustained during acetate infusion, but fell abruptly with termination of infusion. In contrast, insulin levels fell markedly with DCA infusion and remained depressed throughout the infusion and recovery periods. Blood levels of acetate and DCA rose markedly during infusion; however, while acetate levels decreased nearly to control values during the recovery period, DCA levels remained elevated.(ABSTRACT TRUNCATED AT 250 WORDS)