Cyclic AMP Recruits a Discrete Intracellular Ca²⁺ Store by Unmasking Hypersensitive IP₃ Receptors.

ABSTRACT: Inositol 1,4,5-trisphosphate (IP₃) stimulates Ca²⁺ release from the endoplasmic reticulum (ER), and the response is potentiated by 3',5'-cyclic AMP (cAMP). We investigated this interaction in HEK293 cells using carbachol and parathyroid hormone (PTH) to stimulate formation of IP₃ and cAMP, respectively. PTH alone had no effect on the cytosolic Ca²⁺ concentration, but it potentiated the Ca²⁺ signals evoked by carbachol. Surprisingly, however, the intracellular Ca²⁺ stores that respond to carbachol alone could be both emptied and refilled without affecting the subsequent response to PTH. We provide evidence that PTH unmasks high-affinity IP₃ receptors within a discrete Ca²⁺ store. We conclude that Ca

SUBMITTER: Konieczny V 

PROVIDER: S-EPMC5276804 | biostudies-literature | 2017 Jan

REPOSITORIES: biostudies-literature