Morphology of erythrocytes and conformation of hemoglobin-derived hematoporphyrin were studied in patients with coronary heart disease (CHD) and patients with circulatory failure using laser interference microscopy and Raman spectroscopy. Correlation was revealed (r=0.81) between hemoglobin oxygen saturation and oxyhemoglobin fraction in erythrocytes evaluated by Raman spectroscopy. Patients with CHD and patients with circulatory failure showed reduced oxygen-releasing capacity of hemoglobin and hemoglobin content and increased oxygen-binding capacity of hemoglobin, and hemoglobin affinity for oxygen. Significant differences from the control were observed only in patients with circulatory failure. It was found that hemoglobin content, hematocrit, and the shape of erythrocytes during CHD and circulatory failure did not differ from the control, whereas the area of erythrocytes was increased.
Changes in protoporphyrin conformation, partial pressures of O2 and CO2, and the mechanisms responsible for regulation of pCa and pH in erythrocytes were studied in essential hypertension (EH). Changes in protoporphyrin conformation in EH were accompanied by a decrease in the partial pressure of O2 and an increase in the partial pressure of CO2. This was associated with increased activities of Na+/H+-exchange and Ca2+-dependent K+-channels and with a decreased activity of Ca2+-ATPase. The changes in protoporphyrin conformation in EH are suggested to decrease the efficiency of O2 metabolism in hemoglobin and increase the values of intracellular pCa and pH of erythrocytes.
In a direct experiment, the rate constants of photochemical k and non-photochemical k quenching of the chlorophyll fluorescence have been determined in spinach photosystem II (PS II) membrane fragments, oxygen-evolving PS II core, as well as manganese-depleted PS II particles using pulse fluorimetry. In the dark-adapted reaction center(s) (RC), the fluorescence decay kinetics of the antenna were measured at low-intensity picosecond pulsed excitation. To create a "closed" P680Q state, RCs were illuminated by high-intensity actinic flash 8 ns prior to the measuring flash. The obtained data were approximated by the sum of two decaying exponents. It was found that the antennae fluorescence quenching efficiency by the oxidized photoactive pigment of RC P680 was about 1.5 times higher than that of the neutral P680 state. These results were confirmed by a single-photon counting technique, which allowed to resolve the additional slow component of the fluorescence decay. Slow component was assigned to the charge recombination of P680Pheo in PS II RC. Thus, for the first time, the ratio k /k ≅ 1.5 was found directly. The mechanism of the higher efficiency of non-photochemical quenching comparing to photochemical quenching is discussed.
Rhythmic activity, synaptic transmission and propagation of excitation depend on the processes that occur at different cellular levels. Modulation of neuron activity results from the changes of plasma membrane and organelles properties. We aimed to study the relationship between changes of the ion channels activity, membrane microviscosity and amount of bound Ca(2+) under the influence of nitric oxide (NO). We also investigated the effect of NO on the refractive index of neurons. We have shown that NO activates voltage-dependent K(K(V))-channels and leads to the decrease in the amount of membrane-bound and stored Ca(2+). NO causes a decrease in the microviscosity of the membrane of cytosomes and altered refractive index of neurones. The latter can result from the modification of plasma membrane physico-chemical properties and structural changes in the cytoplasm (vesicles movement, reorganisation of cytoskeleton, etc.). It is suggested that long-term modifications of the physico-chemical properties of membranes and reorganisation in the cytoplasm affect neuron activity and signal transmission.
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