Self-organised criticality and noise in single-channel current of voltage-dependent anion channel

¹ Department of Biophysics, University of Delhi South Campus Benito Juarez Road, New Delhi 110021, India
² Department of Physics, Indian Institute of Technology - Kanpur 208016, India
³ Department of Animal Sciences, School of Life Sciences University of Hyderabad - Hyderabad 500046, India

Corresponding author: sgsl@uohyd.ernet.in

Received: 11 June 2005
Accepted: 12 December 2005

Abstract

Noise profile of Voltage Dependent Anion Channel (VDAC) is investigated in open channel state. Single-channel currents through VDAC from mitochondria of rat brain reconstituted into a planar lipid bilayer are recorded under different voltage clamped conditions across the membrane. Power spectrum analysis of current indicates power law noise of nature. Moreover, this nature of the open channel noise is seen throughout the range of applied membrane potential from -30 to +30. It is being proposed that noise in open ion channel arises out of obstruction in the passage of ions across the membrane. The process is recognised as a phenomenon of self-organized criticality (SOC) like sandpile avalanche and other physical systems. Based on SOC it has been theoretically established that the system of ion channel follows power law noise as observed in our experiments. We also show that the first-time return probability of current fluctuations obeys a power law distribution.