The effects of hyperglycaemic hypoxia on rectification in rat dorsal root axons

1. Electrotonic responses to 150 ms current pulses were recorded from isolated rat dorsal roots incubated for at least 3 h with either normal (5 mM) or high (25 mM) D-glucose solutions, and with either normal (25 mM) or low (5 mM) bicarbonate concentrations. 2. On replacement of O2 by N2 for 50 min, all the roots depolarized, but the changes in electrotonus differed systematically. With normal glucose, the depolarization was accompanied by an increase in input conductance. In contrast, for the hyperglycaemic roots the depolarization was slower and accompanied by a fall in input conductance which was exacerbated in low bicarbonate concentrations. 3. The changes induced by hyperglycaemic hypoxia in low bicarbonate could be mimicked by exposure of the roots either to 100% CO2 or to a combination of 3 mM tetraethylammonium chloride and 3 mM 4-aminopyridine, to block both fast and slow potassium channels. 4. These results indicate that the primary mechanism of hypoxic depolarization of these sensory axons is altered by hyperglycaemia. In normoglycaemia, the changes in electrotonus are consistent with an increase in axonal potassium conductance. The block of potassium channels seen in hyperglycaemic hypoxia is attributed to intra-axonal acidification by anaerobic glycolysis and may contribute to the pathogenesis of diabetic neuropathy

The paradox between resistance to hypoxia and liability to hypoxic damage in hyperglycemic peripheral nerves. Evidence for glycolysis involvement

Isolated ventral and dorsal rat spinal roots incubated in normal (2.5 mM) or high glucose (25 mM) concentrations or in high concentrations of other hexoses were exposed transiently to hypoxia (30 min) in a solution of low buffering power. Compound nerve action potentials, extracellular direct current potentials, and interstitial pH were continuously recorded before, during, and after hypoxia. Ventral roots incubated in 25 mM D-glucose showed resistance to hypoxia. Dorsal roots, on the other hand, revealed electrophysiological damage by hyperglycemic hypoxia as indicated by a lack of posthypoxic recovery. In both types of spinal roots, interstitial acidification was most pronounced during hyperglycemic hypoxia. The changes in the sensitivity to hypoxia induced by high concentrations of D-glucose were imitated by high concentrations of D-mannose. In contrast, D-galactose, L-glucose, D-fructose, and L-fucose did not have such effects. Resistance to hypoxia, hypoxia-generated interstitial acidification, and hypoxia-induced electrophysiological damage were absent after pharmacological inhibition of nerve glycolysis with iodoacetate. These observations indicate 1) that enhanced anaerobic glycolysis produces resistance to hypoxia in hyperglycemic peripheral nerves and 2) that acidification may impair the function of peripheral axons when anaerobic glycolysis proceeds in a tissue with reduced buffering power

Alkalinization during re-oxygenation prevents functional damage by hyperglycaemic hypoxia

HYPERGLYCAEMIA impairs recovery from transient cerebral ischaemia: the importance of tissue acidification for this phenomenon has not been clarified in detail. We investigated this issue in a less complex in vitro preparation of isolated rat dorsal spinal roots exposed for 30 min to hyperglycaemic hypoxia. Peak height of compound action potentials recovered minimally in 5 mM bicarbonate. However, recovery was greatly improved by addition of the weak base trimethylamine during re-oxygenation. Addition of the weak acid propionate had no such effect. Cytoplasmic alkalinization improved recovery in a brief time window only: application of trimethylamine after 15 min of re-oxygenation was without beneficial effect. These data emphasize the importance of cytoplasmic acidification for neurophysiological recovery from hyper-glycaemic hypoxia during the initial period of re-oxygenation

Alkalinization during re-oxygenation prevents functional damage by hyperglycaemic hypoxia

HYPERGLYCAEMIA impairs recovery from transient cerebral ischaemia: the importance of tissue acidification for this phenomenon has not been clarified in detail. We investigated this issue in a less complex in vitro preparation of isolated rat dorsal spinal roots exposed for 30 min to hyperglycaemic hypoxia. Peak height of compound action potentials recovered minimally in 5 mM bicarbonate. However, recovery was greatly improved by addition of the weak base trimethylamine during re-oxygenation. Addition of the weak acid propionate had no such effect. Cytoplasmic alkalinization improved recovery in a brief time window only: application of trimethylamine after 15 min of re-oxygenation was without beneficial effect. These data emphasize the importance of cytoplasmic acidification for neurophysiological recovery from hyper-glycaemic hypoxia during the initial period of re-oxygenation

Применение иерархических игр для поддержки и развития отраслей малого бизнеса моногородов

В предоставленной статье рассматривается вопрос монозависимых городов в России, приводящий к проблеме безработицы. В качестве предполагаемой возможности поспособствовать ее решению предлагается рассмотреть возможность применения иерархических игр в качестве средства для развития отраслей малого бизнеса в моногороде

Der Geologische Dienst in Sachsen: Festband zum Jubiläum 150 Jahre Landesgeologie

Der Geologische Dienst von Sachsen feiert im Jahr 2022 sein 150-jähriges Jubiläum – am 6. April 1872 wurde die Geologische Landesuntersuchung im Königreich Sachsen gegründet. Auf 153 Seiten der Reihe „Geoprofil“ werden Einblicke in die Arbeit des Geologischen Dienstes im LfULG, seinen Aufgaben und die Dienste als zuständige Fachbehörde gegeben. Die elf Einzelbeiträge zeigen die aktuellen Herausforderungen und Chancen, die sich aus den Themenbereichen Umwelt, Naturschutz und Geologie für Sachsen stellen. Im Einzelnen geht es in den Beiträgen um die sächsische Rohstoffstrategie, die Suche nach einem Endlagerstandort für radioaktive Abfälle, Erdwärme, Hydrogeologie, die Eisenbahn Neubaustrecke Dresden – Prag, Naturgefahren, das geowissenschaftliche Archiv, Träger öffentlicher Belange (TöB), Geoparks und einen Blick in die 150 jährige Geschichte. Redaktionsschluss: 30.11.202