Oxidants and regulation of K(+)-Cl(-) cotransport in equine red blood cells.
The effect of oxidants on K(+)-Cl(-) cotransport (KCC) was investigated in equine red blood cells. Carbon monoxide mimicked O(2). The substituted benzaldehyde, 12C79 (5 mM), markedly increased O(2) affinity. In N(2), however, O(2) saturation was low (<10%) but KCC remained active. Nitrite (NO(2)(-)) oxidized heme to methemoglobin (metHb). High concentrations of NO(2)(-) (1 and 5 mM vs. 0.5 mM) increased KCC activity above control levels; it became O(2) independent but remained sensitive to other stimuli. 1-Chloro-2, 4-dinitrobenzene (1-3 mM) depleted reduced glutathione (GSH). Prolonged exposure (60-120 min, 1 mM) or high concentrations (3 mM) stimulated an O(2)-independent KCC activity; short exposures and low concentrations (30 min, 0.5 or 1 mM) did not. The effect of these manipulations was correlated with changes in GSH and metHb concentrations. An oxy conformation of Hb was necessary for KCC activation. An increase in its activity over the level found in oxygenated control cells required both accumulation of metHb and depletion of GSH. Findings are relevant to understanding the physiology and pathology of regulation of KCC.
Muzyamba
M C
MC
Department of Veterinary Preclinical Sciences, University of Liverpool, Liverpool L69 7ZJ, United Kingdom.
Speake
P F
PF
Gibson
J S
JS
D000818:Animals; D001547:Benzaldehydes / Q000494:pharmacology; D001693:Biological Transport, Active / Q000187:drug effects; D002248:Carbon Monoxide / Q000493:pharmacokinetics / Q000494:pharmacology; D002352:Carrier Proteins / Q000187:drug effects* / Q000378:metabolism*; D048429:Cell Size / Q000187:drug effects; D004137:Dinitrochlorobenzene / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004912:Erythrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism; D006736:Horses; D007038:Hypotonic Solutions / Q000494:pharmacology; D017136:Ion Transport / Q000187:drug effects; D008706:Methemoglobin / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism / Q000494:pharmacology; D009584:Nitrogen / Q000494:pharmacology; D009994:Osmolar Concentration; D016877:Oxidants / Q000378:metabolism* / Q000494:pharmacology*; D010100:Oxygen / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors; D011188:Potassium / Q000378:metabolism; D027981:Symporters; D014867:Water / Q000378:metabolism; D000096922:K Cl- Cotransporters
D001547:Benzaldehydes; D002248:Carbon Monoxide; D002352:Carrier Proteins; D004137:Dinitrochlorobenzene; D004791:Enzyme Inhibitors; D005978:Glutathione; D007038:Hypotonic Solutions; D008706:Methemoglobin; D009573:Nitrites; D009584:Nitrogen; D016877:Oxidants; D010100:Oxygen; D010749:Phosphoprotein Phosphatases; D011188:Potassium; D027981:Symporters; D014867:Water; D000096922:K Cl- Cotransporters; C039599:5-(2-formyl-3-hydroxyphenoxy)pentanoic acid