Alexander P. Naumov

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Ionic currents in the node of Ranvier bathed in Na-free acid solutions (pH 3.4–4.6) were measured under voltage clamp conditions. Small (less than 0.1 nA) inward currents were detected in Na-free solutions at pH<4.0, whereas only outward currents were observed in Na-free solutions at normal pH. These currents have kinetics and voltage dependence of(More)
The inhibition of the sodium current in nodal membrane at low pH external solutions was studied under voltage clamp conditions. Analysis of the data for membrane potentials from +10 to +150 mV shows that the inhibition of the Na+ currents at high positive potentials cannot be described by a titration curve of a single acid group. The data can be explained(More)
1. The steady-state characteristics of the sodium channel gating in the nodal membrane were determined under voltage clamp conditions before and after treatment with toxins from the venom of scorpion, Buthus eupeus. 2. The apparent binding constant (KA) of the toxin was determined for different levels of the membrane potential. At potentials more negative(More)
Ca2(+)-permeable channels in human carcinoma A431 cells were studied using the patch clamp technique. We have found two types of Ca2(+)-permeable channels which are activated by inositol 1,4,5-trisphosphate (IP3) applied to the intracellular side of the plasma membrane. Unitary conductances of these channels are 3.7 and 13 pS (105 mM Ca2+ in recording(More)
1. To study mechanisms of receptor-operated Ca2+ influx in non-excitable cells, membrane currents of rat peritoneal macrophages were recorded using whole-cell cell-attached and outside-out configurations of the patch clamp technique. Under whole-cell recording conditions, ATP applied in micromolar concentrations elicited an inward current response when the(More)
The activity of potassium channels of canine aortic sarcoplasmic reticulum was measured using the planar lipid bilayer-fusion technique. The channels have a conductance of 208 pS (400/100 mM K+ in cis/trans solutions) and potassium-to-sodium permeability ratio of 7.7 Ba2+ ions produced two main effects: one is the interruption of channel currents for tens(More)
Actions of growth-hormone-releasing hormone (GHRH) on single rat anterior pituitary cells were studied using indo-1 fluorescence to monitor changes in intracellular calcium, [Ca2+]i, and perforated-patch recording to measure changes in membrane potential and ionic currents. GHRH elevated [Ca2+]i in non-voltage-clamped cells by a mechanism that was dependent(More)
1. Ionic currents through the sodium system of nodes of Ranvier treated with aconitine were measured under voltage clamp conditions in a Ringer solution containing Na+ or an equimolar amount of various test cations. 2. Average shifts in reversal potentials in nodes of Ranvier treated with aconitine with NH4+, Li+, K+, Rb+, Cs+ in place of Na+ in the Ringer(More)
The patch-clamp technique was used to study mechanisms of ATP-induced Ca2+ influx in rat peritoneal macrophages. The experiments on whole-cell and patch membranes have shown that extracellular ATP activates channels permeable to di- and monovalent inorganic cations. Ratios of unitary channel conductances in 105 mM Ca2+, Sr2+, Mn2+, Ba2+ and normal sodium(More)