potassium-fluoride and gluconic-acid

Common components of whole-cell internal recording solutions were tested both in vitro and in patch-clamp experiments for their effects on the activity of cAMP-dependent protein kinase. Potassium fluoride (KF), 440 mM trimethylamine chloride and exclusion of bovine serum albumin (BSA) decreased the activity of the enzyme, while ethylene glycol-bis (beta-aminoethyl ether) N,N,N',N'-tetraacetic acid (EGTA) and the potassium salts of aspartate, gluconate, methylsulfate and monobasic phosphate increased its activity. Addition of KF to the internal solution produced a hyperpolarizing shift in the V1/2 of Ih channel activation, consistent with the KF-induced reduction of protein kinase A activity. Therefore, consideration of the composition of internal solutions is warranted when studying channel physiology by patch-clamp techniques.

Topics: Animals; Aspartic Acid; Calcium; Cells, Cultured; Cesium; Chelating Agents; Chlorides; Cyclic AMP-Dependent Protein Kinases; Egtazic Acid; Enzyme Activation; Enzyme Inhibitors; Fluorides; Gluconates; Ion Channels; Isoquinolines; Methylamines; Olfactory Receptor Neurons; Patch-Clamp Techniques; Phosphates; Phosphorylation; Potassium Compounds; Rats; Second Messenger Systems; Serum Albumin, Bovine; Sulfonamides; Sulfuric Acid Esters; Tetraethylammonium

Metabolic pathways of glucose during germination of Bacillus megaterium QM B1551 spores were studied by using specifically labeled glucose and gluconate. The Embden-Meyerhof pathway, the pentose cycle, and the direct oxidation route of glucose to gluconate (the gluconate pathway) were all operative at this stage; among those, gluconate accumulation was most predominant, especially in the early stage. Potassium fluoride, an enolase inhibitor, abolished the catabolism by the Embden-Meyerhof pathway totally without affecting gluconate accumulation. Under these conditions glucose was exclusively oxidized to gluconate. Gluconate thus accumulated could be metabolized further via phosphorylation by gluconate kinase. Remarkable gluconate accumulation was also demonstrated in several other spores requiring alanine as an effective germinant. NADH formed by the direct glucose oxidation may serve as a initial ATP source to phosphorylate glucose in germinating spores.

Topics: Bacillus; Bacillus megaterium; Fluorides; Gluconates; Glucose; Glucose 1-Dehydrogenase; Glucose Dehydrogenases; Hexokinase; Oxidation-Reduction; Phosphogluconate Dehydrogenase; Phosphotransferases; Phosphotransferases (Alcohol Group Acceptor); Potassium; Potassium Compounds; Spores, Bacterial