D. Kaskel

Glycogen Content in the Rabbit Retina in Relation to Blood Circulation

An interruption of the blood circulation in the rabbit eye leads to total loss of histochemically traceable glycogen in the retina after a period of 30–45 min.

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.

[The influence of changes in body position on intraocular pressure, episcleral venous pressure, and blood pressure (author's transl)].

The intraocular pressure, the ophthalmic artery pressure, and the episcleral venous pressure increased after changes from sitting to recumbent body position, whereas the subclavian artery pressure remained unchanged or decreased slightly. Changing from recumbent to sitting position was followed by a decrease in IOP, ophthalmic pressure, and subclavian artery pressure. Comparing the last measurement in the first position to the first value after change, it was found that the IOP alters by about 20%, the ophthalmic artery pressure by 15%, and the episcleral venous pressure by 50%. In all series a decrease in subclavian artery pressure was observed during the first 15 min. The mean pressure in the ophthalmic artery diminished in the series that changed from sitting to recumbent position, whereas it increased in the other series during the first 15 min. The episcleral venous pressure increased more than the corresponding IOP after changing to the recumbent position.The intraocular pressure, the ophthalmic artery pressure, and the episcleral venous pressure increased after change from sitting to recumbent body position, whereas the subclavian artery pressure remained unchanged or decreased slightly. Changing from recumbent to sitting position was followed by a decrease in IOP, ophthalmic pressure, and subclavian artery pressure. Comparing the last measurement in the first position to the first value after change, it was found that the IOP alters by about 20%, the ophthalmic artery pressure by 15%, and the episcleral venous pressure by 50%. In all series a decrease in subclavian artery pressure was observed during the first 15 min. The mean pressure in the ophthalmic artery diminished in the series that changed from sitting to recumbent position, whereas it increased in the other series during the first 15 min. The episcleral venous pressure increased more than the corresponding IOP after changing to the recumbent position. Intraokularer Druck, Blutdruck der A. ophthalmica und Episkleralvendruck stiegen beim Übergang vom Sitzen zum Liegen an, wohingegen der Blutdruck in der A. subclavia unverändert blieb oder geringgradig abfiel. Umgekehrt fielen IOD, Ophthalmica- und Subclaviablutdruck beim Wechsel vom Liegen zum Sitzen. Das Ausmaß des Anstiegs bzw. Falls beim Vergleich von jeweils letztem zu jeweils erstem Meßwert betrug für den IOD ca. 20%, für den Ophthalmicamitteldruck ca. 15% und für den Episkleralvenendruck etwa 50%. Sämtliche Freiwilligen-Gruppen zeigten während der ersten 15min ein Abfallen des Subclaviablutdruckes. Der Ophthalmicamitteldruck fiel bei dem Kollektiv, das zuerst saß, während des Sitzens ebenfalls ab, wohingegen er bei den Freiwilligen, die zuerst lagen, in der ersten Körperposition noch anstieg. Der Episkleralvenendruck stieg nach dem Übergang in die liegende Position stärker als der dazugehörige IOD an.

Blood Pressure, Blood Flow and Intraocular Pressure

(1) A rise of blood pressure by steps between 80 and 180 mm Hg mean pressure did not cause an increase in intraocular pressure under the conditions which are mentioned above. (2) If, however, slight p

[Early effects of clonidine, epinephrine, and pilocarpine on the intraocular pressure and the episcleral venous pressure in normal volunteers (author's transl)].

In four different groups of eight normal volunteers the intraocular (IOP) and episcleral venous pressures (EVP) were measured before, and at 7.5, 15, 30, 45, and 60 min after topical application of one drop of clonidine (1/4%), epinephrine (1%), or pilocarpine (2%) by means of applanation tonometry or the air-jet method, respectively. The results were compared with a control group. In the control group the IOP decreased by 16% until the fourth measurement. Subsequently it increased to -10% after 60 min. The EVP remained unchanged. After clonidine application the IOP decreased throughout the whole experiment (-31% after 1 h) and after the third measurement the IOP decrease was significantly more marked than in the control group. The EVP I diminished significantly during the first 15 min by 25% and then increased, reaching its initial value after 60 min. IOP and EVP I showed parallel behavior only during the first 30 min. Topical application of epinephrine was followed by a much smaller decrease in IOP (17% after 60 min); compared to the control group the differences were minor. The EVP I was reduced significantly by 15% below the initial level after 45 min while EVP and IOP behaved identically. After pilocarpine application the IOP rose initially (7% after 7.5 min) and decreased markedly after 10 min (33% after 1 h). Compared to the untreated volunteers there were significant differences at nearly all times. At the outset the EVP I increased significantly (29% after 7.5 min), and then decreased again until it regained the initial value after 30 min. Only at the beginning of the experiment were the reactions of IOP and EVP similar.In four different groups of eight normal volunteers the intraocular (IOP) and episcleral venous pressures (EVP) were measured before, and at 7.5, 15, 30, 45, and 60 min after topical application of one drop of clonidine (1/4%), epinephrine (1%), or pilocarpine (2%) by means of applanation tonometry or the air-jet method, respectively. The results were compared with a control group. In the control group the IOP decreased by 16% until the fourth measurement. Subsequently it increased to −10% after 60 min. The EVP remained unchanged. After clonidine application the IOP decreased throughout the whole experiment (−31% after 1 h) and after the third measurement the IOP decrease was significantly more marked than in the control group. The EVP I diminished significantly during the first 15 min by 25% and then increased, reaching its initial value after 60 min. IOP and EVP I showed parallel behavior only during the first 30 min. Topical application of epinephrine was followed by a much smaller decrease in IOP (17% after 60 min); compared to the control group the differences were minor. The EVP I was reduced significantly by 15% below the initial level after 45 min while EVP and IOP behaved identically. After pilocarpine application the IOP rose initially (7% after 7.5 min) and decreased markedly after 10 min (33% after 1 h). Compared to the untreated volunteeers there were significant differences at nearly all times. At the outset the EVP I increased significantly (29% after 7.5 min), and then decreased again until it regained the initial value after 30 min. Only at the beginning of the experiment were the reactions of IOP and EVP similar. An 4 Gruppen von jeweils 8 augengesunden Freiwilligen wurden vor, 7,5, 15, 30, 45 und 60 min nach Applikation von jeweils einem Tropfen Clonidin 1/4% (Isoglaukon®), Adrenalin 1% (Eppy®) und Pilocarpin 2% (Isopto-Pilocarpin®) der Augeninnendruck applanatorisch und der Episkleralvenendruck mit dem Airjet-Verfahren gemessen und mit einer gleichgroßen Gruppe, die keine Tropfen erhielt, verglichen. In der Kontrollgruppe sank der Augeninnendruck bis zum 4. Meßpunkt (nach 30 min) um 16% und stieg danach nicht signifikant an (−10% nach 60 min). Der Episkleralvenendruck blieb unverändert. Unter Clonidin sank der Augeninnendruck während der gesamten Untersuchung (−31% nach 60 min). Im Vergleich mit dem Leerversuch fielen die Augendruckabnahmen vom 3. Meßzeitpunkt an signifikant stärker aus. Der Episkleralvenendruck I fiel signifikant um 25% in der ersten Viertelstunde ab; danach stieg er an und erreichte nach 50 min wieder den Ausgangswert. Lediglich in der ersten halben Stunde zeigten i.o. Druck und Episkleralvenendruck I ein paralleles Verhalten. Unter Adrenalin fiel der Augeninnendruck wesentlich geringer als unter Clonidin ab (17% nach 60 min). Verglichen mit dem Leerversuch waren die Unterschiede gering. Der Episkleralvenendruck I sank spät von 5. Meßpunkt an signifikant (15%) unter das Ausgangsniveau ab. Episkleralvenendruck I und Augendruck verhielten sich zu keinem Zeitpunkt unterschiedlich. Nach Philocarpinapplikation stieg der intraokulare Druck zunächst an (7% nach 7,5 min und begann nach 10 min kräftig zu fallen (33% nach 60 min). Im Vergleich zur Kontrollgruppe waren fast zu allen Zeitpunkten signifikante Unterschiede vorhanden. Der Episkleralvenendruck I stieg anfangs signifikant an (29% nach 7,5 min) und fiel dann wieder, um nach etwa 30 min sein Ausgangsniveau zu erreichen. Nur zu Beginn der Untersuchung zeigten intraokularer Druck und Episkleralvenendruck I ein ähnliches Verhalten.

Localization of Glycogen in Lenses of Different Species, Demonstrated by Histochemical Methods

The well-known fact that several animal species show considerable differences in the glycogen content of the lens can be demonstrated histochemically. The localization of glycogen is most striking in

Enzymologic and histologic investigations in normal and pressure-ischemic retina of rabbits

Histologic investigations together with histochemical and photometric measurements of enzyme activities were performed in retina of rabbits, whose blood supply had been totally interrupted for 1h. A retinal edema developed affecting the internal layers between the inner limiting membrane and the internal plexiform and ganglion cell layer. Although this edema was quite remarkable at the posterior pole of the eye, it diminished toward the periphery, disappearing near the ora serrata. The activities of the following enzymes were investigated: hexokinase, glucose 6-phosphate dehydrogenase, aldolase, glyceraldehydephosphate dehydrogenase, lactate dehydrogenase, malate dehydrogenase, succinate dehydrogenase, ATPase, and phosphorylase. The most striking finding was the total disappearance of phosphorylase activity under pressure ischemia. ATPase and aldolase showed a decreased activity in the ischemic retina, and malate dehydrogenase a slightly diminished one. Concerning the other enzymes, no significant differences between normal and ischemic retina were observed. An Kaninchen-Netzhäuten, deren Durchblutung für die Dauer einer Stunde völlig unterbrochen worden war, wurden histologische Untersuchungen sowie histochemische und spektralphotometrische Enzymaktivitätsbestimmunge durchgeführt. Es entwickelte sich ein retinales Ödem in den inneren Schichten zwischen der inneren Grenzmembran und der inneren plexiformen und Ganglienzellschicht. Das Ödem war am hinteren Augenpol ziemlich ausgeprägt, verminderte sich jedoch zur Peripherie hin und verschwand völlig nahe der Ora serrata. Die Aktivität folgender Enzyme wurde untersucht: Hexokinase, Glukose-6-Phosphatdehydrogenase, Aldolase, Glycerinaldehydphosphatdehydrogenase, Laktatdehydrogenase, Malatdehydrogenase, Succinatdehydrogenase, ATPase und Phosphorylase. Das auffallendste Ergebnis war das völlige Verschwinden der Phosphorylaseaktivität unter Druckischaemie. ATPase und Aldolase zeigten eine verminderte Aktivität und Malatdehydrogenase eine leicht verringerte Aktivität in der ischaemischen Retina. Alle anderen Enzyme ließen keine signifikanten Unterschiede zwischen normaler und ischaemischer Netzhaut erkennen.

Composition of Aqueous Humour and Lens After Carotid Ligation

Studies on the effect of unilateral carotid ligation on the composition of aqueous humour and lens have been performed with rabbits. The concentrations of some substrates and intermediates of carbohydrate catabolism (glucose, fructose, glucose-6-phosphate, fructose-6-phosphate, fructose-1, 6-diphosphate, dihydroxyacetone-phosphate, pyruvate, lactate) and urea were investigated. The content of free adenosine nucleotides was measured in the lens. With certain substrates significant differences in aqueous humour as well as in the lens could be observed 3 h after carotid ligation. The possible causes of these changes are discussed

Determination of pseudofacility in man

Based on a new method of measuring episcleral venous pressure (EVP), i.e., using the ‘air-jet principle’ of Krakau et al. (1973), pseudofacility was determined in 20 human eyes. According to Báránys formula, a mean value of 23.3 % of the total facility was found, and a mean value of 16.9 % according to Goldmanns formula. Bei 20 gesunden Probanden beiderlei Geschlechts mit einem Durchschnittsalter von 28 Jahren wurde die Pseudofacility nach den von Bárány und Goldmann vorgeschlagenen Verfahren ermittelt. Die Anwendung der Bárányschen Formel ergab 23,3 % Anteil der Pseudofacility an der Gesamtfacility, die der Goldmannschen Formel 16,9 %.

Effect of Unilateral Pressure Ischaemia on the Carbohydrate Metabolism in Ocular Tissues

Glucose, fructose, pyruvate, lactate, ATP, ADP, and AMP concentrations in iris, ciliary body, lens, retina, choroid, and vitreous body were determined biochemically in the eyes of 15 albinotic rabbits