Brown adipose tissue mitochondria of cold-acclimated rats: change in characteristics of purine nucleotide control of the proton electrochemical gradient
| Autor: | Jean Himms-Hagen, Michel Desautels |
|---|---|
| Rok vydání: | 1981 |
| Předmět: |
Male
Purine medicine.medical_specialty Acclimatization Mitochondrion Biology Guanosine Diphosphate Membrane Potentials chemistry.chemical_compound Oxygen Consumption Adipose Tissue Brown Internal medicine Brown adipose tissue Electrochemistry medicine Animals Nucleotide Electrochemical gradient Membrane potential chemistry.chemical_classification General Medicine Hydrogen-Ion Concentration Guanine Nucleotides Thermogenin Mitochondria Rats Cold Temperature medicine.anatomical_structure Endocrinology chemistry Protons Thermogenesis Body Temperature Regulation |
| Zdroj: | Canadian Journal of Biochemistry. 59:619-625 |
| ISSN: | 0008-4018 |
| Popis: | Growth of brown adipose tissue in cold-acclimated rats, known to result in a large increase in capacity for noradrenaline-induced thermogenesis, is accompanied by changes in mitochondria (increase in concentration of binding sites for GDP with no change in affinity and increase in proportion of a 32 000 polypeptide in the inner membrane) which suggest an increased concentration of thermogenic proton conductance pathways. The objective of this study was to find out whether respiratory properties of brown adipose tissue mitochondria of cold-acclimated rats also change in a way which is in keeping with an increased thermogenic function in the cold-acclimated state. Mitochondria from both warm-acclimated and cold-acclimated rats were completely uncoupled when isolated and both albumin and guanosine diphosphate (GDP) were necessary for maintenance of a maximum proton electrochemical gradient. The maximum rate of loosely coupled respiration was, however, the same in the two types of mitochondria and appeared to be limited by the activity of substrate dehydrogenases rather than by the proton permeability of the mitochondria. The relation between proton electrochemical gradient and respiration was the same in the two types of mitochondria. However, mitochondria from cold-acclimated rats required three to four times more GDP to maintain a given proton electrochemical gradient, a difference due to altered sensitivity of the transmembrane pH gradient and not the membrane potential component. Because of this increased need for purine nucleotides, mitochondria of brown adipose tissue of the cold-acclimated rat in vivo may be in a more loosely coupled state and hence more susceptible to regulation by substrate availability. |
| Databáze: | OpenAIRE |
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