Mechanosensitivity of the BK Channels in Human Glioblastoma Cells: Kinetics and Dynamical Complexity

BK channels are potassium selective and exhibit large single-channel conductance. They play an important physiological role in glioma cells: they are involved in cell growth and extensive migrating behavior. Due to the fact that these processes are accompanied by changes in membrane stress, here, we examine mechanosensitive properties of BK channels from human glioblastoma cells (gBK channels). Experiments were performed by the use of patch-clamp method on excised patches under membrane suction (0–40 mmHg) at membrane hyper- and depolarization. We have also checked whether channel’s activity is affected by possible changes of membrane morphology after a series of long impulses of suction. Unconventionally, we also analyzed internal structure of the experimental signal to make inferences about conformational dynamics of the channel in stressed membranes. We examined the fractal long-range memory effect (by R/S Hurst analysis), the rate of changes in information by sample entropy, or correlation dimension, and characterize its complexity over a range of scales by the use of Multiscale Entropy method. The obtained results indicate that gBK channels are mechanosensitive at membrane depolarization and hyperpolarization. Prolonged suction of membrane also influences open–closed fluctuations—it decreases channel’s activity at membrane hyperpolarization and, in contrary, increases channel’s activity at high voltages. Both membrane strain and its “fatigue” reduce dynamical complexity of channel gating, which suggest decrease in the number of available open conformations of channel protein in stressed membranes

On the simple random-walk models of ion-channel gate dynamics reflecting long-term memory

Several approaches to ion-channel gating modelling have been proposed. Although many models describe the dwell-time distributions correctly, they are incapable of predicting and explaining the long-term correlations between the lengths of adjacent openings and closings of a channel. In this paper we propose two simple random-walk models of the gating dynamics of voltage and Ca2+-activated potassium channels which qualitatively reproduce the dwell-time distributions, and describe the experimentally observed long-term memory quite well. Biological interpretation of both models is presented. In particular, the origin of the correlations is associated with fluctuations of channel mass density. The long-term memory effect, as measured by Hurst R/S analysis of experimental single-channel patch-clamp recordings, is close to the behaviour predicted by our models. The flexibility of the models enables their use as templates for other types of ion channel

On the Larch'e--Cahn theory for stress-induced diffusion

Simon, Aleksander M.; Grzywna, Zbigniew J.. (1991). On the Larch'e--Cahn theory for stress-induced diffusion. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/1712

Growth driven by diffusion

Luczak, Jerzy; Gadomski, Adam; Grzywna, Zbigniew J.. (1991). Growth driven by diffusion. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/4676

Abstract Lossy dictionary-based image compression method

In this paper, we report on the new method of image compression. The method is based on LZ77 dictionary algorithm. We introduce two modifications such as quantization and noise levels. Experimental results presented in this paper prove that the new method of image compression gives promising results as compared with original LZ77 dictionary algorithm and JPEG2000. Ó 2006 Elsevier B.V. All rights reserved

On the Analysis of Concentration-Dependent Diffusion Using Transient Sorption and Permeation Measurements by the <i>D</i>₁–<i>D</i>₈ System

A set of methods (<i>D</i>₁–<i>D</i>₈ transient sorption and permeation analysis system) previously used for the regular inhomogeneous membranes, that is, the membranes where the diffusive properties vary regularly along the diffusion axis, has been applied to the concentration-dependent diffusion in order to deliver experimental protocols to recover the notion of the diffusion coefficient. On the basis of the numerical studies of <i>c</i>_t = (<i>D</i>(<i>c</i>)<i>c</i>_<i>x</i>)_<i>x</i> for carefully chosen set of <i>D</i>(<i>c</i>) functions, the “diagnostic system” has been created. It provides a possibility of a realistic estimation of the <i>D</i>(<i>c</i>) relationship as well as the reasons for the deviations of the transient measurements from the ideal Fickian behavior