Subcellular particles (mitochondria, cellular pigments etc.) are mainly responsible for light scattering in living tissues in relation to the functional state. 2-D images clarify the respective tissue status during normoxia or anoxia such as the redox state of cytochromes. We realized tissue imaging of twelve isolated perfused rat livers stained with Merocyanine-540 during normoxia, hypoxia and anoxia. Merocyanine-spectra have shown a maximum fluorescence peak at 596 +/- 2 nm. The optical response increased under desoxygenation and decreased under reoxygenation and might be correlated to electrical potential alterations. Furthermore, we record oscillations with frequencies over 7/sec (420/min) which might be correlated to intracellular processes. The additional use of dyes for tissue imaging gives us the opportunity of new insights into organ function.
Spectrometry is a well established method for in vitro and in vivo measurements. For interpretation of experimental results and patient monitoring it is important to regard the catchment volume and penetration depth of backscattered light. We investigated different suspensions of rat liver mitochondria as well as rat liver homogenate in a scattering chamber combined with a scanning procedure. To compare these results with a common used medium we measured Lipofundin 2% additionally. The highest light intensity caused Lipofundin 2%, followed by 100% mitochondrial concentration, liver homogenate and 50% mitochondrial concentration. Most of times the light penetrates slightly pronounced in lateral than in forward direction. Furthermore, we investigated the dependence of optical fibers with different thickness on catchment volume and penetration depth. Optical fibers were applied with a diameter of 200 micrometers and 250 micrometers respectively presenting a great increase in catchment volume and penetration depth in the larger one.
Various medications affect the systemic circulation and organ oxygenation causing dilatation or constriction of blood vessels. Imminent liver failure can be generated by reduced perfusion of different origins. In this case hepatic vasodilatation would be a therapeutical approach for improving patient's condition. Our examinations have been performed in perfused rat liver using spectrometric methods. Two defined areas of the liver were measured punctually. We compared the influence of Tetramethylpyrazine and Glyceroltrinitrate on hemoglobin oxygenation (HbO2) and concentration (Hb-conc.) in rat liver after application of Norepinephrine, which caused a mid decrease in hemoglobin oxygenation of 47,9 %. Both increased the HbO2, but differed from each other in manner of time and extent. Tetramethylpyrazine indicated a longer effect than Glyceroltrinitrate. Furthermore, HbO2 and Hb-conc. showed a conversed relation. From the shape of the absorption spectra it is possible to derive the oxygenation of hemoglobin.
Complex multi-component systems are dominated in organs. Different functional structures could be partly represented as highly dynamic alterations of light scattering. In our institute we apply micro-lightguides and optical systems for monitoring subcellular structures. By creating 3D images after staining an isolated perfused rat liver with the potential sensitive fluorescence dye Merocyanine-540 we found an astonishing relation between morphological and functional aspects changeable by oxygenation or desoxygenation. Moreover, the simultaneous practice of 2D-spectroscopy could clarify cellular processes like e. g. potential changes. Merocyanine-540 spectra of stained rat liver have shown their maximum in light intensity at 596 +/- 2 nm in dependence on depolarisation, hyper- or repolarisation. In addition, we found lower peaks in difference spectra, which could be associated with the cytochromes aa3, b and c. There has been an interesting correlation to the redox state of cytochromes during anoxic or oxic liver perfusion. Every peak has shown consistent oscillations with frequencies over 7/sec (420/min), which might be caused by membrane processes. In five experiments we compared functional and morphological aspects in 2D- and 3D-images of stained liver tissue.
In organs we can find signal changes between vascular and parenchymal cells. We started to combine spectral measurements by the use of merocyanine in isolated perfused rat liver to analyze the alterations of dc-potentials. There have been first experiments with Merocyanine (M-540) in the seventies with stained axons and hearts to measure optical action potentials (Morad, Salama, et al, 1978). It is reported that the increase of fluorescence response is connected to a depolarization and its decrease to a repolarization. Tissue imaging after staining with this dye should be ideal for a long term interpretation of dc-potential alterations as an analysis of the electrical coupling in different cell types under various experimental conditions like anoxia or temperature changes.
Living tissue of mammals contains a large amount of subcellular particles like mitochondria that are involved in light scattering. Since these particles correlate in a certain way with the functional status of cells, light scattering may be useful for monitoring of functional tissue state. With EMPHO SSK Oxyscan we investigated functional parameters in a new kind of isolated perfused pig heart model. In this perfusion model we use organs obtained from the abattoir that are reperfused by use of a heart-lung machine. By creating 3D images of tissue light scattering we found an interesting relation between morphological structures of myocardium and the patterns of the 3D images. Additionally, we created 3D images of myoglobin oxygenation. Furthermore, we got spectra showing the redox state of cytochromes. We believe that this new kind of tissue imaging method will give us the opportunity to get new insights into myocardial function.
Light scattering in tissue of mammals and humans is affected by subcellular structures. Since these structures correlate well with the status of cells and tissue, light scattering seems to be ideal for monitoring of functional tissue state. By use of EMPHO SSK Oxyscan we investigated functional parameters in a novel kind of isolated perfused pig heart model. In this perfusion model we use organs obtained by the local slaughterhouse that are reanimated at our institute by application of a heart-lung machine. By creating 3D-images of tissue scattering we found an interesting relation between anatomical structures of myocardium and the 3D-images. Additionally, we detected coherence between backscattered light intensity and functional tissue status. Furthermore, we got a sight into the redox state of cytochrome aa3, b and c by creating difference spectra. We believe that this new kind of tissue imaging method will give us the opportunity to get new insights into myocardial function.
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