Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

It is controversial whether the Ca2+ mobilizing agent, cADP-ribose (cADPR), is implicated in secretagogue-mediated intracellular Ca2+ responses of pancreatic beta-cells. In this study we utilised a potent antagonist of cADPR, 8-amino-cADPR, to determine whether cADPR is involved in glucose-, acetylcholine-, caffeine- and nitric oxide-induced intracellular Ca2+ responses of isolated rat beta-cells. The antagonist was found to be effective in the complete inhibition of cADPR-induced Ca2+ release from sea urchin egg microsome preparations, when used at equivalent concentrations to cADPR (between 0.1-10 microM) in the assay. Isolated beta-cells were co-loaded with up to 50 microM 8-amino-cADPR, and Fura-2 or Fluo-3, by the whole-cell patch technique. At this concentration, the antagonist failed to affect standard glucose- and acetylcholine-induced increases in the intracellular free Ca2+ ([Ca2+]i) of isolated rat pancreatic beta-cells, as assessed by video ratio imaging and single wavelength microfluorimetry. Applying the same methodology, the antagonist also failed to affect NO- and caffeine-induced intracellular Ca2+ responses of rat beta-cells. These results suggest that cADPR does not appear to play a fundamental role in beta-cell Ca2+ signalling. As a control, patch-loading with heparin (2 mg/ml) however, abolished the acetylcholine response but neither affected the NO- or caffeine-induced mobilization of intracellular Ca2+. These results support the involvement of the IP3-receptor in acetylcholine-induced mobilization of intracellular Ca2+, but not that invoked by caffeine.

Original publication

DOI

10.1016/0143-4160(95)90056-x

Type

Journal article

Journal

Cell Calcium

Publication Date

11/1995

Volume

18

Pages

411 - 419

Keywords

Acetylcholine, Adenosine Diphosphate Ribose, Animals, Caffeine, Calcium, Calcium Channel Blockers, Cyclic ADP-Ribose, Ion Transport, Nitric Oxide, Pancreas, Patch-Clamp Techniques, Rats, Rats, Wistar