Cooling Reduces cAMP-Stimulated Exocytosis and Adiponectin Secretion at a Ca2+-Dependent Step in 3T3-L1 Adipocytes

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El Hachmane, MichaelGothenburg University,Göteborgs universitet,Institutionen för neurovetenskap och fysiologi, sektionen för fysiologi,Institute of Neuroscience and Physiology, Department of Physiology (author)

We investigated the effects of temperature on white adipocyte exocytosis (measured as increase in membrane capacitance) and short-term adiponectin secretion with the aim to elucidate mechanisms important in regulation of white adipocyte stimulus-secretion coupling. Exocytosis stimulated by cAMP (included in the pipette solution together with 3 mM ATP) in the absence of Ca2+ (10 mM intracellular EGTA) was equal at all investigated temperatures (23 degrees C, 27 degrees C, 32 degrees C and 37 degrees C). However, the augmentation of exocytosis induced by an elevation of the free cytosolic [Ca2+] to similar to 1.5 mu M (9mMCa(2+) + 10 mM EGTA) was potent at 32 degrees C or 37 degrees C but less distinct at 27 degrees C and abolished at 23 degrees C. Adiponectin secretion stimulated by 30 min incubations with the membrane permeable cAMP analogue 8-Br-cAMP (1 mM) or a combination of 10 mu M forskolin and 200 mu M IBMX was unaffected by a reduction of temperature from 32 degrees C to 23 degrees C. At 32 degrees C, cAMP-stimulated secretion was 2-fold amplified by inclusion of the Ca2+ ionophore ionomycin (1 mu M), an effect that was not observed at 23 degrees C. We suggest that cooling affects adipocyte exocytosis/adiponectin secretion at a Ca2+-dependent step, likely involving ATP-dependent processes, important for augmentation of cAMP-stimulated adiponectin release.

Komai, Ali,1987Gothenburg University,Göteborgs universitet,Institutionen för neurovetenskap och fysiologi, sektionen för fysiologi,Institute of Neuroscience and Physiology, Department of Physiology(Swepub:gu)xkomal (author)
Olofsson, Charlotta S,1971Gothenburg University,Göteborgs universitet,Institutionen för neurovetenskap och fysiologi, sektionen för fysiologi,Institute of Neuroscience and Physiology, Department of Physiology(Swepub:gu)xoloch (author)
Göteborgs universitetInstitutionen för neurovetenskap och fysiologi, sektionen för fysiologi (creator_code:org_t)

By the author/editor: El Hachmane, Mic ...; Komai, Ali, 1987; Olofsson, Charlo ...

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MEDICAL AND HEALTH SCIENCES: MEDICAL AND HEAL ...; and Basic Medicine; and Physiology

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