title: Hamster brown-adipose-tissue mitochondria. The role of fatty acids in the control of the proton conductance of the inner membrane.
abstract: The specific ability of fatty acids to increase the proton conductance of the inner membrane of mitochondria from the liver and brown adipose tissue of cold-adapted hamsters was compared. The liver and brown-adipose-tissue mitochondria had their effective proton conductances increased by respectively 0.028 and 0.94 nmol H+- min-1. (mV of proton electrochemical gradient)-1 for each nmol of palmitate bound. No difference could be detected between the abilities of liver and brown-adipose-tissue mitochondria to bind fatty acids. Purine nucleotides did not displace farry acids from the brown-adipase-tissue mitochondria. The endogenous fatty acid content of hamster brown-adipose-tissue mitochondria prepared in the absence of album was found to be equivalent to 17 +/-  7 nmol of palmitate/mg protein. The fatty acid content was reduced to 1 nmol/mg after preincubation of the mitochondria with CoA, ATP and carnitine. No inert pool of fatty acids could be detected. The endogenous fatty acids of hamster liver mitochondria were less than 4 nmol of palmitate equivalent/mg protein. Some of the fatty acid associated with the brown-adipose-tissue mitochondria originates during preparation of the mitochondria. In the light of these results, the physiological role of the fatty acids in controlling the proton conductance of the brown-adipose-tissue mitochondrial inner membrane, and hence- non-shivering thermogenesis, is re-evaluated.
mesh_terms: D000064:Acclimatization; D000273:Adipose Tissue / Q000378:metabolism*; D002001:Adipose Tissue, Brown / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D001692:Biological Transport; D002331:Carnitine / Q000494:pharmacology; D003080:Cold Temperature; D006224:Cricetinae; D004553:Electric Conductivity; D005227:Fatty Acids / Q000502:physiology; D007700:Kinetics; D008566:Membranes / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism; D009829:Oleic Acids / Q000378:metabolism; D009928:Organ Specificity; D010169:Palmitic Acids / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D005227:Fatty Acids; D009829:Oleic Acids; D010169:Palmitic Acids; D002331:Carnitine