Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nitrites Help To Struggle Against Ischemia Retinae

27.03.2008
Nitrites dilate vessels in case of hypoxia and protect retina from ischemia.

The conclusion has been made by specialists of the Moscow Research Institute for Eye Diseases named after Gelmholtz and the N.M. Emanuel Institute of Biochemical Physics, Russian Academy of Sciences. Their discovery is the outcome of a series of experiments on rabbits. It is premature to talk about its clinical use.

Ischemia is a rather widespread pathology of retina and optic nerve. It is provoked by different reasons, including primary hypertension and insular diabetes. An important role in retina pathology development is played by shortage of nitric oxide, which is synthesized in the organism from arginine. Theoretically speaking, nitrites can turn into nitric oxide under the influence of some enzymes. However, till recently, nobody could prove that such reaction does take place in a living organism. The Moscow researchers succeeded to do that based on the acute ischemia retinae model developed by them.

The rabbit is a favorite object for ophthalmologists’ investigations. The animals underwent laser coagulation of eye-ground vessels. The experimentalists have chosen such a place for exposure so that several impulses could capture the maximum number of vessels and if possible not to traumatize surrounding tissues. The laser provokes stable vasospasm and, consequently, ischemia. The outcomes of researchers’ action were estimated by the rabbits’ eye-ground photographs.

After coagulation, the rabbits’ eye vessels become desolate and abruptly reduced in diameter. Right after laser exposure, sodium nitrite in physiological solution was intraperitoneally introduced to the rabbits on the basis of 20 mg per 1 kilogram of live weight. As soon as a quarter of an hour after the injection, the retina vessels directly behind the laser impact zone began to fill with blood and the blood circulation restored in them. At that, the nitrite injection to an animal with normal vessels almost did not provoke their dilation. The researchers assume that nitrite in the organism is able to quickly reduce to nitric oxide, which sharply relaxes vessels, but only in case of oxygen shortage.

In the course of a next series of experiments the researchers clarified if preliminary nitrite injection prevented vessel constriction. For this end, a rabbit was initially injected sodium nitrite, and 15 minutes later the researchers cauterized vessels by laser and observed changes in them. In this case, laser impact provoked only a short-term vasospasm of the vessel, which quickly filled with blood and restored the “flow capacity”.

The same results were obtained by the researchers via an independent method when observing changes in photoelectric activity of a rabbit’s retina. The electroretinogram analysis has shown that laser coagulation of vessels impairs functional state of retina, which restores within 7 days without outside interference. The sodium nitrite injection right after laser coagulation accelerates the rehabilitation process significantly, and the preparation injection prior to laser exposure virtually fully protects retina from injury. At that, even strong laser impact can not provoke abrupt constriction and desolation of animals’ vessels.

Thus, the outcomes obtained by two independent methods prove that nitrites presence in vessels protects the retina from acute ischemia. Mechanism of such action, apparently, consists in the fact that under oxygen shortage in the organism, sodium nitrite can reduce to nitric oxide at concentrations that are sufficient for full vessel relaxation.

Olga Myznikova | alfa
Further information:
http://www.informnauka.ru

Further reports about: Injection Laser Oxide Protect Retina coagulation ischemia nitric nitrite outcome sodium vessel

More articles from Life Sciences:

nachricht Rainbow colors reveal cell history: Uncovering β-cell heterogeneity
22.09.2017 | DFG-Forschungszentrum für Regenerative Therapien TU Dresden

nachricht The pyrenoid is a carbon-fixing liquid droplet
22.09.2017 | Max-Planck-Institut für Biochemie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>