NADH-dependent respiration in osmotically inactive swollen mitochondria: does transport replace phosphorylation in mediating respiratory control in swollen mitochondria?
Rotenone-sensitive, uncoupler-insensitive, NADH-dependent respiration was demonstrated in osmotically inactive fragments of the mitochondrial inner-membrane obtained following high amplitude (spontaneous) swelling. This NADH-dependent respiration as well as mitochondrial ATPase activity was stimulated by ligands which are known to be transported by specific transporters/mechanisms. The ligands capable of this anomalous respiratory control included several intermediates of the citric acid cycle, besides non-metabolizable ligands including lactate, cations such as K+ and Ca2+. The interaction between NADH-dependent respiration and these ligands, as manifested by stimulation of respiration, was strongly ionic strength-dependent. The thermodynamic relationship between respiratory control and stimulation of transport ATPase by the relevant transportable ligands could also be demonstrated in the conventional (rat liver) microsomes. These experimental results offer a novel experimental base for search into an intra-membranous mechanism of energy transduction.
Sitaramam
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V
Department of Zoology, University of Poona, Pune.
Sambasivarao
D
D
D000818:Animals; D001693:Biological Transport, Active; D066298:In Vitro Techniques; D008930:Mitochondria, Liver / Q000378:metabolism*; D008933:Mitochondrial Swelling; D009243:NAD / Q000378:metabolism; D009995:Osmosis; D010101:Oxygen Consumption; D010766:Phosphorylation; D051381:Rats; D011919:Rats, Inbred Strains
D009243:NAD