The nature of the protein phosphatases involved in the regulation of glycolysis/gluconeogenesis, fatty acid synthesis and cholesterol synthesis in rat liver has been investigated using L-pyruvate kinase, ATP-citrate lyase, acetyl-CoA carboxylase and hydroxymethylglutaryl-CoA reductase as substrates. The results show that protein phosphatases-1, 2A and 2C are the only significant protein phosphatases in rat liver acting on these four substrates. The relationship of these three enzymes to other protein phosphatases described in the literature is discussed.Glycolysis, gluconeogenesis and the synthesis of lipids (fatty acid and cholesterol) are under hormonal control; several key regulatory enzymes in these metabolic pathways are known to be controlled by phosphorylation-dephosphorylation reactions. The conversion of phosphoenolpyruvate to pyruvic acid by L-pyruvate kinase is an important control point in both glycolysis and gluconeogenesis in mammalian liver. L-pyruvate kinase is phosphorylated on a single serine residue by cyclic-AMP-dependent protein kinase, increasing its K , for phosphoenolpyruvate and decreasing its Ki for ATP and alanine.
Overdosage of muscle relaxant has been given as a possible explanation for the hypotensive episodes occurring during the management of tetanus. The aim of the present work was to study the pharmacokinetics of pancuronium during long term infusion. Pancuronium was administered to eight patients with severe tetanus for a period varying from 8 to 24 days. The concentration of pancuronium was measured daily in plasma and urine using a fluorimetric method. The plasma concentration varied from 0.27 to 0.48 microgram/ml. No tendency to accumulation was observed. The plasma concentration fell rapidly below the level associated with muscle relaxation when pancuronium was discontinued. This absence of accumulation can be explained by a rapid elimination of pancuronium through the kidney according to a process of ultrafiltration.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations鈥揷itations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.