Kinetic and steady-state characteristics of sodium channels modified by aconitine

Kinetic and steady-state characteristics of sodium channels of the Ranvier node membrane, modified by aconitine, were investigated by the voltage clamp method. Channels modified by aconitine were shown to be only partially inactivated. Dependence of the fraction of uninactivated channels on voltage can be described by a model of a channel with three states: closed, open, and inactivated. It is suggested that aconitine does not significantly change the parameters of the inactivated state. Repolarization of the membrane to between –70 and –110 mV after a long (10 msec) test shift of potential induces initially a rapid decline of the current ("tail"), followed by a slow rise to the steady-state value. To explain the kinetics of this current it is necessary to postulate two or more open states of the channel.Institute of Cytology, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 12, No. 6, pp. 612–618, November–December, 1980.     

Increase in Sensitivity of HEK293FT Cells to Influenza Infection by CRISPR-Cas9-Mediated Knockout of IRF7 Transcription Factor

Russian Journal of Bioorganic Chemistry - Interferon-regulated factors play a central role in the activation of the innate immune response. The interferon-regulatory factor 7 (IRF7) is one of the...     

Orthologous gene-expression profiling in multi-species models: search for candidate genes

Microarray-driven gene-expression profiles are generally produced and analyzed for a single specific experimental model. We have assessed an analytical approach that simultaneously evaluates multi-species experimental models within a particular biological condition using orthologous genes as linkers for the various Affymetrix microarray platforms on multi-species models of ventilator-associated lung injury. The results suggest that this approach may be a useful tool in the evaluation of biological processes of interest and selection of process-related candidate genes.     

Physiological Heterothallism and Sexuality in Euascomycetes: A Partial History

Copyright 1998 Academic Press.     

Reversible derivatization to enhance enzymatic synthesis: chemoenzymatic synthesis of doxorubicin-14-O-esters

An efficient three-step, chemoenzymatic synthesis of unprotected doxorubicin-14-O-esters from doxorubicin hydrochloride salt is described. The key step is a lipase-catalyzed regioselective transesterification/esterification using commercially available acyl donors and doxorubicin reversibly derivatized with N-alloc to improve substrate loadings. The overall yield is ca. 60% and chromatographic purification is not required, thereby making the process more amenable to scale-up.     

Selectivity and sensitivity to hydrogen ion blocking of batrachotoxin-modified sodium channels in nerve fiber membrane

Currents through batrachotoxin-modified sodium channels were measured by the voltage clamp method on the Ranvier node membrane. In experiments with replacement of Na⁺ in the external solution by K⁺ or NH ₄ ⁺ the following series of permeabilities, determined as reversal potentials according to the equation of a static field, was obtained — P_Na: \(P_{NH_4 }\) :P_K=1:0.47:0.19. The relative permeability for H⁺ was determined by measuring currents after replacement of Na⁺ in the external solution by nonpenetrating choline ions and lowering pH to 3.7–3.8. The ratio p_H/p_Na for sodium channels modified by batrachotoxin averaged 528±46. Modified channels were less sensitive to the blocking action of H⁺ than normal sodium channels. The difference in the effective values of pK of the acid group of normal and modified channels was 0.40–0.45.