Modulation of the hepatocyte rough endoplasmic reticulum single chloride channel by nucleotide-Mg2+ interaction.
The effect of nucleotides on single chloride channels derived from rat hepatocyte rough endoplasmic reticulum vesicles incorporated into bilayer lipid membrane was investigated. The single chloride channel currents were measured in 200/50 mmol/l KCl cis/trans solutions. Adding 2.5 mM adenosine triphosphate (ATP) and adenosine diphosphate (ADP) did not influence channel activity. However, MgATP addition inhibited the chloride channels by decreasing the channel open probability (Po) and current amplitude, whereas mixture of Mg(2+) and ADP activated the chloride channel by increasing the Po and unitary current amplitude. According to the results, there is a novel regulation mechanism for rough endoplasmic reticulum (RER) Cl(-) channel activity by intracellular MgATP and mixture of Mg(2+) and ADP that would result in significant inhibition by MgATP and activation by mixture of Mg(2+) and ADP. These modulatory effects of nucleotide-Mg(2+) complexes on chloride channels may be dependent on their chemical structure configuration. It seems that Mg-nucleotide-ion channel interactions are involved to produce a regulatory response for RER chloride channels.
Cellular and Molecular Research Center, Department of Physiology and Pharmacology, Babol University of Medical Sciences, Babol, Iran. mnrashrafpour@yahoo.com
M
M
Ashrafpour
J Fahanik
JF
Babaei
R
R
Saghiri
H
H
Sepehri
H
H
Sharifi
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000244:Adenosine Diphosphate / Q000494:pharmacology*; D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D065101:Chloride Channel Agonists; D018118:Chloride Channels / Q000037:antagonists & inhibitors* / Q000378:metabolism; D018870:Endoplasmic Reticulum, Rough / Q000187:drug effects / Q000502:physiology*; D022781:Hepatocytes / Q000187:drug effects / Q000502:physiology; D015640:Ion Channel Gating / Q000187:drug effects; D008297:Male; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar
D065101:Chloride Channel Agonists; D018118:Chloride Channels; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid