Triphenylmethylphosphonium cation distribution as a measure of hormone-induced alterations in white adipocyte membrane potential

Journal Article · Fri Jan 01 04:00:00 EST 1982 · J. Membr. Biol.; (United States)

DOI:https://doi.org/10.1007/BF01872254· OSTI ID:6710478

Vallano, M L; Sonenberg, M

Triphenylmethylphosphonium (TPMP+) partitions into the mitochondrial and cytosolic compartments in the rat white adipocyte in a potential-dependent fashion. The relationship between (/sup 3/H)TPMP+ distribution, intracellular cAMP generation and lipolysis in response to hormones and cAMP-mimetic compounds was examined. Half-maximal (/sup 3/H)TPMP+ efflux and glycerol release were produced by 15 and 9 nM adrenocorticotropin, 170 and 110 nM 1-epinephrine, 70 and 27 microM isobutylmethylxanthine and 800 and 750 microM dibutyryl cAMP, respectively. Hormone-stimulated cAMP generation was also correlated with (/sup 3/H)TPMP+ efflux and lipolysis in terms of concentration dependency. In kinetic experiments, glycerol release and (/sup 3/H)TPMP+ efflux in response to adrenocorticotropin or cholera toxin proceeded over a similar time course, whereas an earlier rise in cAMP generation was detected. The depolarizing effect of lipolytic compounds was localized to the mitochondrial compartment. When cells were incubated in elevated-(K+)0 buffer, the stimulatory effect of dibutyryl cAMP on (/sup 3/H)TPMP+ efflux and lipolysis persisted, suggesting that maintenance of the plasma membrane potential is not critical for demonstration of these responses. When the extracellular concentration of serum albumin, which provides binding sites for free fatty acids, was increased from 1 to 3%, an increase in glycerol release and a decrease in (/sup 3/H)TPMP+ efflux was observed. We suggest that intracellular free fatty acid accumulation in response to lipolytic agents causes dissipation of the mitochondrial membrane potential and efflux of (/sup 3/H)TPMP+ from the organelle and cell.

• Research Organization: Memorial Sloan-Kettering Cancer Center, New York, New York
• OSTI ID: 6710478
• Journal Information: J. Membr. Biol.; (United States), Journal Name: J. Membr. Biol.; (United States) Vol. 68:1; ISSN JMBBB
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
62 RADIOLOGY AND NUCLEAR MEDICINE
AMP
ANIMAL CELLS
ANIMALS
BIOCHEMICAL REACTION KINETICS
CELL CONSTITUENTS
CELL MEMBRANES
CONNECTIVE TISSUE CELLS
FAT CELLS
HORMONES
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
MAMMALS
MEMBRANE TRANSPORT
MEMBRANES
MITOCHONDRIA
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANOIDS
PHOSPHORUS COMPOUNDS
RATS
REACTION KINETICS
RODENTS
SOMATIC CELLS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES