[Power metabolism from neurons and a glia to the whole brain: norm, pathology and correction].

The review outlines current state of the thepretical, methodological and applies aspects of brain's energy homeostasis. Authors suggest reconsidering the exclusive role of glucose as an energy substrate (ES) at both neuronal and systemic levels discussing recent research data on qualitative composition of ES pool in the brain. The role of ES alternative to glucose, e.g., lactate and ketone bodies, is examined. The hypotheses of intracellular and astrocyte-neuron lactate shuttles are discussed along with the hypotheses of astrocyte-neuron shuttle of ketone bodies, the selfish brain theory and suppositions on homeostatic versus non-homeostatic ES supply chains. In conclusion, authors argue that exogenous native ES may be used for prevention and treatment of neurodegenerative diseases.

[Stimulus-dependent blockade of the Na channels of isolated myocardial cells in the rat by the anti-arrhythmia agent N-propyl ajmaline (neogiluritmal)]. / Stimulzavisimaia blokada Na-kanalov izolirovannykh kletok miokarda krysy antiaritmikom N-propil-aimalinom (neogiluritmalem).

The patch-clamp method was used to study the effect of N-propyl ajmaline (NPA) on sodium currents (INa) in enzymatically isolated cells of adult rats. When applied at concentrations of 10(-5)--2 X 10(-5) M NPA produced a use-dependent inhibition of INa. The rate and depth of this blockade increased with NPA concentration, frequency and magnitude of depolarizing pulses. Voltage dependence of the blockade was revealed beyond the potential range where the fraction of activated Na channels was close to 1.0. Turning on the strong hyperpolarizing prepulse (100-ms duration) before each test pulse induced a prompt increase of INa (due to the removal of resting inactivation) which declined pulse by pulse during subsequent repetitive stimulation. A single long-lasting (3000 ms) depolarizing step, in contrast to the train of short (5 ms) depolarizing pulses did not enhance appreciably the blocking action of NPA. From an analysis of the data obtained it was inferred that NPA inhibits INa due to a voltage-dependent interaction with open Na channels. It is emphasized that NPA has similar blocking effects on Na channels in myocardial cells and nerve fibers.

[Inactivation of fast sodium current across the membrane of isolated cardiocytes]. / Protsess inaktivatsii bystrogo natrievogo toka cherez membranu odinochnykh serdechnykh kletok.

Inactivation of sodium conduction across the membrane of rat single heart cells was studied by the patch-voltage-clamp method. The development of sodium channel inactivation was found to be double-exponential. Dependence of both time constants on the membrane potential was measured. The time course of the recovery of the sodium conduction from inactivation was sigmoidal in shape with marked retardation at the beginning. The data obtained are not covered by the Hodgkin-Huxley formalismus.

["Micro-lead" technic for recording ion currents through the membranes of individual myocardial cells]. / Metod "mikrootvedeniia" dlia registratsii ionnykh tokov cherez membranu odinochnykh serdechnykh kletok.

Patch-voltage-clamp method has been used for registration of the fast inward current in single heart muscle cells. Ionic current were measured on a small patch of membrane which is of about 1/200-1/300 of the total cell surface (diameter of patch is of about 5 micrometer). To correct the distortions of raw signal caused by the stray capacity in feedback of current-voltage converter and adjustable increasing of high-frequency gain was used. This allows one to shorten the net time of transient process in response to switching the command potential up to 30 microseconds. The channel population in membrance patch of micrometer in diameter is, on the one hand, large enough to record directly the integral ionic current and is, on the other hand, small enough for fluctuations of ionic current to be pronounced. This circumstance permits the method to be applied for ionic current investigations both by the classical methods and by statistical analysis.