Evidence for a large conductance voltage gated cationic channel in rough endoplasmic reticulum of rat hepatocytes.
In this work, we report the single channel characterization of a voltage gated cationic channel from rough endoplasmic reticulum (RER) membranes of rat hepatocytes incorporated into a planar lipid bilayer. The channel was found to be cation selective with a main conductance of 598+/-20 pS in 200 mM KCl cis/50 mM KCl trans. The channel open probability appeared voltage dependent with a voltage for half activation (V(1/2)) of 38 mV and an effective gating charge z of -6.66. Adding either 4-AP (5 mM) or ATP (2.5 mM) to the side corresponding to the cell internal medium caused a strong inhibition of the channel activity. This channel is likely to be involved in maintaining proper cation homeostasis in the RER of hepatocytes.
Sepehri
Hamid
H
Department of Physiology and Neuroscience Research Center, Shaheed Beheshti Medical University, Tehran, Iran.
Eliassi
Afsaneh
A
Sauvé
Rémy
R
Ashrafpour
Manoucher
M
Saghiri
Reza
R
D015761:4-Aminopyridine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D002412:Cations / Q000378:metabolism; D004553:Electric Conductivity; D018870:Endoplasmic Reticulum, Rough / Q000502:physiology*; D022781:Hepatocytes / Q000166:cytology; D066298:In Vitro Techniques; D015640:Ion Channel Gating; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D008051:Lipid Bilayers / Q000378:metabolism; D008862:Microsomes, Liver / Q000187:drug effects / Q000502:physiology*; D010713:Phosphatidylcholines / Q000378:metabolism; D051381:Rats
D002412:Cations; D007473:Ion Channels; D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D000255:Adenosine Triphosphate; D015761:4-Aminopyridine