Inge Korte

Glycogen concentration changes in retina, vitreous body and other eye tissues caused by disturbances of blood circulation

The glycogen content in the individual eye tissues is strongly correlated to blood supply. Our investigations on the retina of bovines, which have not been fully evaluated, show that the time interval between interruption of blood supply and preparation of the retina is of special importance. Pressure ischemia affects a decrease in glycogen content in the retina and vitreous of rabbits, which is, however, less distinct in the vitreous. Decrease of glycogen with ischemia also takes place in the cornea and, to a lesser degree, in iris and choroid. In contrast, there is no decrease in the glycogen content of the lens. Changes in glycogen content of the rabbit retina after ligation of the A. carotis communis is less distinct than with pressure ischemia. in the vitreous, changes in glycogen content could not be observed. Values measured in both tissues of the ligated eye decrease with additional pressure ischemia. Der Glykogengehalt der einzelnen Augengewebe hängt stark mit der Durchblutung zusammen. Unsere nicht weiter ausgewerteten Versuche an Rindernetzhäuten zeigen, daß die Zeit zwischen Unterbindung der Durchblutung und Präparation der Netzhaut einen großen Einfluß besitzt. Unter Druckischämie kommt es in Netzhaut und weniger stark ausgeprägt im Glaskörper von Kaninchen zu einer Glykogenverminderung. Auch in der Hornhaut, weniger in Iris und Aderhaut tritt bei Ischämie ein Abfall des Glykogengehaltes auf. Im Gegensatz dazu findet man in der Linse keine Abnahme im Glykogengehalt. Die Veränderungen im Glykogengehalt der Netzhaut nach Unterbindung der A. carotis communis ist weniger stark ausgeprägt, als bei der Druckischämie. Im Glaskörper ist durch die Ligatur keine Änderung zu erkennen. Die Werte der beiden Gewebe im ligierten Auge sinken bei zusätzlicher Druckischämie ab.

Studies on the Citric Acid Cycle and its Portion of Glucose Breakdown by Calf and Bovine Lenses in vitro

The content of the free adenine nucleotides, of pyruvic acid, of citric acid and the oxygen consumption after inhibition with KCN were determined in bovine lenses and compared with normal values. Prod

Utilization of Fructose-1,6-Diphosphate as Glycolytic Substrate in Bovine Lens Homogenates

Cortex and nucleus of bovine lenses of different ages were homogenized and incubated in the presence of glucose at 37°C for different periods. A balance of the free adenine nucleotides is produced, which is nearly independent of the amount of glucose added (12.5; 25; 37 mM) and shows certain deviations from the physiologic values. These might be interpreted as due to a decreased rate of glycolytic catabolization. Possibly the phosphorylation of the glucose, which is present in sufficient amounts, is inhibited. If, for instance, fruetose-l,6-diphosphate in a concentration of 10−4 M is added to homogenates with such a disturbed nucleotide balance, a normalization takes place within 30 min, and the values of the initial physiologic equilibrium are restored. Due to the difference in the metabolic condition, there are differences between the behaviour of the cortex homogenate and that of the nucleus. The original equilibrium of the free nucleotides present in homogenates of lens nuclei is more stable during incubation in the presence of glucose. Most obvious is the improvement of the equilibrium in the presence of fructose-1,6-diphosphate. Besides the analytical evaluation of the free nucleotides the values of the concentrations of di-hydroxyacetone-phosphate, pyruvic acid and lactate clearly show that fructose-1,6-diphosphate may be utilized as a substrate for the glycolysis of lens homogenates.

Über die Einwirkung von Ouabain auf den Stoffwechsel von Rinder- und Kälberlinsen

Influence of ouabain on the metabolism of calf- and bovine-lenses in-vitro was studied. We tested: Opacity, uptake of water, ratio of K∶Na, intermediates of glycolysis, diphospho-pyridine-nucleotides and adenosine-nucleotides. The latter showed a clear shift from ATP to AMP after treatment with ouabain. Ratio of K∶Na in lenses was decreased, regardless of the ouabain-concentration, compared with non-treated lenses. Intermediates of glycolysis and diphosphopyridin-nucleotide did not change their concentrations. Der Einfluß von Ouabain auf den Stoffwechsel von Kälber- und Rinderlinsen in-vitro wurde untersucht. Geprüft wurden neben dem makroskopischen Aussehen: Quellung, Quotient aus K∶Na, mehrere Glykolyse-Zwischenprodukte, Gehalt an Diphosphopyridin-nucleotid und an Adenosinnucleotiden. Letztere zeigen in ihrer Verteilung eine deutliche Verschiebung von ATP zu AMP nach Behandlung mit Ouabain. Der Quotient K∶Na wies unabhängig von der Ouabainkonzentration gegenüber den nicht behandelten Linsen niedrigere Werte auf, Glykolyse-Zwischenprodukte und Diphosphopyridin-nucleotid zeigten sich unverändert.

Alterations of Lens Metabolism with Experimentally Induced Cataract in Rats

Rat lenses with experimentally induced cataract (either by naphthalene or by streptozotocin) were analyzed biochemically. Both noxae had some effects in common. Water-soluble protein and aldose reductase activity decreased, and glucose-6-phosphate dehydrogenase, phosphofructokinase and glutathione reductase activity increased. A specific effect of streptozotocin was the rise in glucose, fructose and sorbitol. A specific effect of naphthalene was increased amounts of water-insoluble protein.

In vitro Inkubation von Linsen

When bovine lens homogenate was treated with bencyclane-hydrogen-fumarate, the carbohydrate metabolism was activated. This may chiefly be due to the fumarate part of the substance. A 24 H In vitro incubation of whole bovine lenses in TC-199 with and without bencyclane-hydrogen-fumarate did not show the above effect. On the model of former investigations by J.E. Harris et al. we modified the test procedure by selecting the medium and the time of incubation so that the endogenous carbohydrates of the lens were consumed, thus creating new metabolic balances. This metabolic condition allows investigations intended to activate metabolic processes and to restore the steady state of metabolic parameters. We investigated the effect of bencyclane-hydrogen-fumarate using the same method and found that given certain conditions the lens recovers when incubated for 2 h in TC-199 (containing 1 g glucose/1) with addition of a 10(-4) M solution of bencyclane-hydrogen-fumarate. The ATP-content of these lenses in particular gives proof of this result. As already observed in former investigations on homogenates, this effect is probably due to metabolization of the fumarate part of the bencyclane-hydrogen-fumarate by the citric acid cycle. The method used explains the differences observed when using lens homogenates or whole lenses under the same experimental conditions.When bovine lens homogenate was treated with bencyclane-hydrogen-fumarate, the carbohydrate metabolism was activated. This may chiefly be due to the fumarate part of the substance. A 24 h in vitro incubation of whole bovine lenses in TC-199 with and without bencyclane-hydrogen-fumarate did not show the above effect. On the model of former investigations by J.E. Harris et al. we modified the test procedure by selecting the medium and the time of incubation so that the endogenous carbohydrates of the lens were consumed, thus creating new metabolic balances. This metabolic condition allows investigations intended to activate metabolic processes and to restore the steady state of metabolic parameters. We investigated the effect of bencyclane-hydrogen-fumarate using the same method and found that given certain conditions the lens recovers when incubated for 2 h in TC-199 (containing 1 g glucose/l) with addition of a 10−4M solution of bencyclane-hydrogen-fumarate. The ATP-content of these lenses in particular gives proof of this tesult. As already observed in former investigations on homogenates, this effect is probably due to metabolization of the fumarate part of the bencyclane-hydrogen-fumarate by the citric acid cycle. The method used explains the differences observed when using lens homogenates or whole lenses under the same experimental conditions. Mit Bencyclan-hydrogenfumarat (BCHF) hatten wir in Rinderlinsenhomogenaten eine Aktivierung im Kohlenhydratabbau erzielen können, die vor allem auf der Metabolisierung des Fumaratanteils der Substanz beruhen dürfte. In Versuchen mit normalen Rinderlinsen bei 24stündiger in vitro Inkubation in TC-199 mit und ohne Zusatz von BCHF konnte der Homogenateffekt nicht beobachtet werden. In Anlehnung an Versuche von Harris u. Mitarb. änderten wir die Versuchsanordnung durch Wahl eines Inkubationsme diums und Inkubationszeit, bei der die Linse ihre endogenen Kohlenhydrate verbrauchen und damit zu neuen Stoffwechselgleichgewichten kommen muß. In diesem Zustand des Stoffwechsels können Prüfungen erfolgen, die eine Aktivierung von Stoffwechselprozessen zum Ziel haben. Mit diesem Modell haben wir die Wirkung von Bencyclan-hydrogenfumarat untersucht und festgestellt, daß bei Vorliegen bestimmter Ausgangsbedingungen die Erholung der Linsen während einer 2stündigen Inkubation in TC-199, die ja 1 g Glukose/Liter enthält, durch BCHF-Zusatz in 10−4 molarer Konzentration aktiviert werden kann, wofür besonders die Werte des ATP-Gehaltes dieser Linsen sprechen. Dieser Effekt der Metabolisierung des Fumarsäureanteils im BCHF wird dem Zitronensäurezyklus zugeschrieben.

Veränderungen im Glutathion- und Ascorbinsäuregehalt von Rinderlinsen in Abhängigkeit vom Lebensalter

Changes in concentrations of GSH and ascorbic acid and thendependence on age have been investigated in whole lenses and single lens parts of bovines. The values for both substances, referred to lens weight, showed maximum concentrations at an age of 10 to 20 months, thereafter a continuous decrease of concentrations could be observed during the process of aging. In the metabolically active parts of the lens, such as equator, anterior and posterior cortex, there is significantly more GSH and ascorbic acid than in the lens nucleus, which holds true for all periods investigated. The article also reports values for glutathione and ascorbic acid of rat lenses aged 75–150 days. Die Konzentrationsänderungen von Glutathion (GSH) und Ascorbinsäure wurden sowohl in ganzen Linsen als auch in einzelnen Linsenteilen von Rindern in Abhängigkeit vom Lebensalter untersucht. Es ergab sich bei beiden Substanzen bei Normierung der Werte auf das Linsengewicht eine maximale Konzentration im Alter von etwa 10–20 Monaten, danach ist eine kontinuierliche Konzentrationsabnahme mit dem Älterwerden zu beobachten. Die stoffwechselaktiven Teile der Linse (Äquator, vordere und hintere Schale) enthalten in allen untersuchten Altersstufen signifikant mehr GSH und Ascorbinsäure als der Linsenkern. Glutathion- und Ascorbinsäurewerte für Rattenlinsen im Alter zwischen 75 und 150 Tagen werden ebenfalls mitgeteilt.

Is it possible to maintain a normal glutathione level in lenses in vitro

In most types of experimentally induced cataracts, glutathione (GSH) content decreases considerablybefore the onset of opacity. GHS may provide a protective function for protein SH groups by scavenging oxidative products that may impair lens metabolism. To avoid impairment of lens metabolism by decreased levels of GSH it may be possible in vitro: (1) to stimulate GSH synthesis by enrichment of the incubation medium with the amino acids necessary for GSH synthesis or (2) to enrich the incubation medium with the tripeptide itself so that it can be taken up by the lens.Both approaches were investigated with bovine lenses. Lenses were incubated in pairs in a salt solution without carbohydrates, so as to deplete lens of GSH. Following starvation, one lens of each pair was incubated for recovery in TCM 199 enriched with MgSO4 and the three amino acids of GSH; the other lens was put into a freshly prepared salt solution. After 6 h, lenses from the recovery solution contained more GSH than the other lenses. Addition of fructose-1,6-diphosphate to the medium enhanced this effect. When, after starvation, lenses were incubated in the presence of different amounts of GSH, GSH lens content rose, with the highest in those lenses incubated in a medium with a final molarity of 4 × 10−3M GSH. Therefore, incubation of lenses depleted of GSH in medium with either the amino acids of GSH or GSH itself appear to facilitate recovery of GSH content.

Influence of Catalin® (1-Hydroxy-pyrido-(3,2α)-5-phenoxazone-3-carboxylic acid) on the Sorbitol Content of Incubated Bovine Lenses

48 h incubation of bovine lenses was performed in which one lens of a pair was subjected to Catalin® (0.6 × 10––4 M), the other serving as control. Subsequently, the sorbitol concentrations were determined. Lenses under the influence of Catalin showed a significantly decreased concentration in sorbitol. The possible mode of action is discussed.

Studies on the Influence of 1-Hydroxy-Pyrido-(3,2a)-5-Phenoxazone-3-Carboxylic Acid on the Carbohydrate Metabolism of the Lens

The in vitro influence of 1-hydroxy-pyrido-(3,2a)-5-phenoxazone-carboxylic acid (Catalin®) on the metabolism of calf and bovine lenses was studied. After a 48 h pairwise incubation