Adrenergic potentiation of endoplasmic reticulum Ca2+ release in brown fat cells
| Author(s) | Eric V. Leaver and Pamela A. Pappone |
| Journal | Am J Physiol Cell Physiol, 282 |
Method Extract | |
| ... ...acquired at 510-nm emission via a charge-coupled device camera connected to a personal computer running IonWizard software (IonOptix, Milton, MA). The image acquisition rate was typically 0.1 Hz but was sometimes set to 0.4 Hz during agonist presentation... ... | |
Abstract | |
| We find that the adrenergic agonist isoproterenol increases intracellular Ca2+ concentration ([Ca2+]i) in cultured rat brown adipocytes. At the concentration used (10 µM), isoproterenol-induced Ca2+ responses were sensitive to block by either 1- or -adrenergic antagonists, suggesting an interaction between these receptor subtypes. Despite reliance on -adrenoceptor activation, the Ca2+ response was not due solely to increases in cAMP because, administered alone, the selective 3-adrenergic agonist BRL-37344 or forskolin did not increase [Ca2+]i. However, increased cAMP elicited vigorous [Ca2+]i increases in the presence of barely active concentrations of the -adrenergic agonist phenylephrine or the P2Y receptor agonist UTP. Consistent with isoproterenol recruiting only inositol 1,4,5-trisphosphate (IP3)-sensitive Ca2+ stores, endoplasmic reticulum store depletion by thapsigargin blocked isoproterenol-induced Ca2+ increases, but removal of external Ca2+ did not. These results argue that increases in cAMP sensitize the IP3-mediated Ca2+ release system in brown adipocytes. | |
Our Ref: 1511