The effect of beta-adrenergic agonists on the membrane potential of fat-cell mitochondria in situ.
1. The accumulation of [3H]methyltriphenylphosphonium by isolated fat-cells was used to estimate the membrane potential of mitochondria in situ. 2. Adrenaline caused a large decrease in the accumulation of [3H]methyltriphenylphosphonium. Mitochondria in fat-cells incubated in the presence of adrenaline had a very low calculated membrane potential. This effect was also given by isoprenaline (a beta-adrenergic agonist) and was blocked by propranolol (a beta-adrenergic antagonist). 3. The effect of isoprenaline could be partially antagonized by the use of media with high albumin concentrations. Addition of sodium oleate to saturate the fatty acid-binding sites on the albumin reversed this antagonism. 4. It is proposed that the decrease in the calculated mitochondrial membrane potential is due to the uncoupling effect of the non-esterified fatty acids released by the stimulation of lipolysis observed in the presence of beta-adrenergic agonists.
D000273:Adipose Tissue / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D004837:Epinephrine / Q000494:pharmacology*; D007425:Intracellular Membranes / Q000187:drug effects / Q000378:metabolism; D007545:Isoproterenol / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D009861:Onium Compounds; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D014320:Triphenylmethyl Compounds / Q000378:metabolism
D009861:Onium Compounds; D014320:Triphenylmethyl Compounds; C011561:triphenylmethylphosphonium; D011433:Propranolol; D007545:Isoproterenol; D004837:Epinephrine