Download PDF
Horm Metab Res 1995; 27(9): 408-414
DOI: 10.1055/s-2007-979989
Originals Basic

© Georg Thieme Verlag Stuttgart · New York

Adenosine A1-Receptors Inhibit cAMP and Ca2+ Mediated Calcitonin Secretion in C-Cells

A. Zink1 , H. Scherübl2 , M. Höflich1 , J. Hescheler3 , F. Raue1
  • 1Abteilung Innere Medizin I, Universität Heidelberg, Heidelberg, Germany
  • 2Abteilung Innere Medizin, Freje Universität Berlin, Berlin, Germany
  • 3Pharmakologisches Institut, Freie Universität Berlin, Berlin, Germany
Further Information

Publication History

1995

1995

Publication Date:
23 April 2007 (online)

Also available at
  PDF Download  Permissions and Reprints

Abstract

The effect of the adenosine A1 receptor activation on calcitonin secretion was studied in medullary thyroid carcinoma cells of the rat (rMTC 6 - 23). Calcitonin was determined by radioimmunoassay, intracellular cAMP by protein binding assay, intracellular calcium in fura-2 loaded single cells using microspectrofluorimetry, and calcium channel activity by patch clamp technique. The adenosine A1 receptor analogue N-6 phenylisopropyladenosine (PIA) (10-10 - 10-6 M) inhibits dose-dependently glucagon (10-7 M) and rGRH (10-7 M) stimulated CAMP formation and calcitonin secretion. These effects were partly abolished by pretreatment with pertussis toxin (PT) (100 ng/ml). PIA (10-10 - 10-6 M) also suppressed extracellular calcium-stimulated calcitonin secretion, rises in intracellular calcium, and calcium channel currents. PT (100 ng/ml) pretreatment again partly abolished this inhibitory effect. The addition to the medium of adenosine deaminase (0.4 U/ml) stimulated calcitonin secretion. Our results suggest that in calcitonin-secreting cells A1 receptors couple to adenylate cyclase and calcium channels via PT-sensitive G proteins and thus inhibit calcitonin secretion. Adenosine seems to act as an autocrine/paracrine factor in calcitonin-secreting cells.

Key words

Calcitonin - Adenosine - A1-Receptors - C-Cells - cAMP - Intracellular Calcium