The specific binding capacity for purine nucleotides in brown-adipose-tissue mitochondria is thought to indicate the capacity of the proton-conductance pathway which leads to uncoupled respiration. This functional relationship was investigated in studies measuring initial Ca2+-uptake rates and membrane potential in the presence or absence of GDP in brown-adipose-tissue mitochondria with different GDP-binding capacities. The mitochondria from pre-obese and obese ob/ob mice were less able than those from lean control mice to dissipate membrane potential in the absence of GDP. Mitochondria from the obese animals also maintained a higher Ca2+-uptake rate without GDP in comparison with the rate found with mitochondria from the lean mice. The GDP-dependence of Ca2+ uptake was greater in brown-adipose-tissue mitochondria from cold-adapted animals than in those from animals kept at 22 degrees C or at thermoneutrality (33 degrees C). It is concluded that Ca2+-uptake rate and membrane-potential values are depressed in the absence of GDP and indicate indirectly the influence of purine nucleotides on maintaining the proton electrochemical gradient in brown-adipose-tissue mitochondria. It is also apparent that the lower GDP-binding capacity in mitochondria from ob/ob mice is related to a decreased ability to dissipate the proton electrochemical gradient.
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Research Article| July 15 1983
The influence of GDP on Ca2+ uptake by mitochondria of brown adipose tissue from lean and genetically obese (ob/ob) mice
Biochem J (1983) 214 (1): 171–175.
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P Trayhurn, D R Fraser; The influence of GDP on Ca2+ uptake by mitochondria of brown adipose tissue from lean and genetically obese (ob/ob) mice. Biochem J 15 July 1983; 214 (1): 171–175. doi: https://doi.org/10.1042/bj2140171
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