Using the electron probe microanalysis, potassium and sodium concentrations were measured in Wistar rat cardiac muscle cells. Hypoxic conditions were modeled according to the protocol of global ischemia in the absence of perfusion or via anoxic perfusion without glucose. It was shown that depending on the scheme of realization of hypoxia the change with time of the intracellular potassium and sodium balance had different character. Based on the obtained data, the sequence of activation of the hypoxia-specific mechanisms of ion transport on the cardiomyocyte membrane is considered.

Electron probe microanalysis was employed to determine the elemental concentration (K,Na,Cl) in a myocyte on cryosections of the papillary muscle of the isolated rat (Wistar) heart. Protocols of global ischemia and ischemic conditions under glucose-free anoxic perfusion were applied. It was shown that global ischemia induces potassium deficiency (94 +/- 2 mM) in the myocyte and an increase in the level of sodium (72 +/- 4 mM) and chlorine (42 +/- 1 mM) in the cytoplasm compared with intact cell (122 +/- 2; 36 +/- 1; 24 +/- 1 mM). Glucose-free anoxic perfusion leads to a smooth fall of potassium concentration in the cell up to 54 +/- 2 mM with the retention of intracellular sodium (40 +/- 1 mM) and chlorine (26 +/- 1 mM) level. The present finding suggest that, in early ischemia, specific membrane mechanisms of ion transport are activated. Among these are KNa channel, Hi(+)-Nao+ exchange, KATP channel, lactate transport from the cell, associated either with potassium efflux to the extracellular space or chlorine influx into the myocyte. It is assumed that Na/K-ATPase is also activated under ischemic conditions.

Electron probe nuicroanalysis was employed to determine the elemental concentration (K,Na,Cl) in a myocyte on cryosections of the papillary muscle of the isolated rat (Wistar) heart. Protocol's of global ischemia and ischemic conditions under glucose-free anoxic perfusion Were applied. It. was shown that global ischemia induces potassium deficiency (94 +/- 2 mM) in the myocyte And an increase in the level of sodium (72 +/- 4 mM) and chlorine (42 +/- 1 mM) in the cytoplasm compared with intact cell (122 +/- 2; 36 +/- 1; 24 +/- 1 mM). Glucose-free anoxic perfusion leads to a smooth fall, of potassium concentration in the cell up to 54 +/- 2 mM with the retention of intracellular sodium (40 +/- 1 mM). and chlorine (26 +/- 1 mM) level. The present findings suggest that, in early ischemia, specific membrane mechanisms of ion transport are activated. Among these are K-Na. channel, H-i(+),-Na-o(+) exchange, K-ATP channel, lactate transport from the cell, associated either with potassium efflux to the extracellular space or chlorine influx. into the myocyte. It is assumed that Na/K-ATPase is also activated under ischemic conditions.

It has been hypothesized that cardiac ischaemia induces some changes in the cardiac myocyte element. In the present study we analysed whether the imbalance of potassium, sodium and calcium in cardiomyocyte may be coupled with ischaemic conditions, using a perfused heard as a model. Electron Probe Microanalysis (EPMA) of papillary muscle cryosection was employed to examine the intracellular content of elements. Following a 30 min acute ischaemia the intracellular potassium was not changed and sodium was reduced. During a prolonged ischaemia (45 min) [K] loss was shown and [Na] concentration was seen reestablished. These results demonstrate that the active transport of potassium and sodium is possible at the beginning of ischaemia. This suggests that under abaerobic conditions Na-K-ATPase may be functionally coupled with an ATP-sensitive K channel through intracellular messenger, possibly ATP.

The collection of original field bird sound recordings made by Prof. B.N. Veprintsev in 1960-1975 is systematized; the audiomaterials are documented to conform with the international standards. The materials are used in studying taxonomy, phylogeny, comparative ethology, microevolution, faunistics, inventory, and identification of birds by sound in nature. The development of a catalog system and a computerized database provide a reliable and quick search for the necessary material in the collection. The marking of original field tapes for species cuts, verification of identifying species and main indertifying sounds, and the description of the sound background result in the minimization of probable errors, when using the collection materials. The more accurate specification of dates and localities of recordings, safekeeping of the author's comments and introduction of additional information make the materials more valuable for scientific research. The technical data given permit one to assess the restrictions related to the equipment and materials used.