In vivo beta-adrenergic induction of the unmasking of the uncoupling protein in rat brown fat.
1. In 28 degrees C adapted rats (WA) both cold stress and norepinephrine (NE) led to a 4-fold increase of uncoupling protein dependent proton conductance which was abolished by propranolol (PRO). 2. In 4-day warm re-exposed rats (after 10 days at 5 degrees C) (WR) the same uncoupling by cold stress was observed but the NE effect was lower. Uncoupling by cold stress was not abolished by PRO. 3. In WR rats, uncoupling was not due to the involvement of an alpha-adrenergic pathway. 4. Both beta-agonist isoproterenol and beta 3-agonists BRL 35135A and ICI D7114 led to high levels of unmasking. 5. Interscapular brown adipose tissue surgical denervation, which abolished cold stress unmasking both in WA and, WR rats, indicates a mediation by direct sympathetic innervation. 6. Depending on the thermal history of the rat, the possibility that unmasking by cold stress could be mediated by different types of beta-receptors is discussed.
Goubern
M
M
Laboratoire d'Adaptation Energétique à l'Environnement, EPHE, Paris, France.
Chapey
M F
MF
Laury
M C
MC
Portet
R
R
D002001:Adipose Tissue, Brown / Q000378:metabolism* / Q000502:physiology; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D003080:Cold Temperature; D007473:Ion Channels; D008297:Male; D008564:Membrane Potentials; D008565:Membrane Proteins / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D013312:Stress, Physiological; D000071256:Uncoupling Protein 1
D002352:Carrier Proteins; D007473:Ion Channels; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D011943:Receptors, Adrenergic, beta; D000071256:Uncoupling Protein 1; D009638:Norepinephrine