Tumor-related selection of calcium signals in vasopressin
-stimulated human adenomatous corticotrophs.
Corcuff, Jean-Beno[diaeresis]ot, Nathalie C. Guerineau, Antoine
Tabarin, and Patrice Mollard.
Laboratory of Neurophysiology, Centre National de la Recherche
Scientifique, URA 1200, Universit[umlaut]a de Bordeaux II, and
Endocrinological Department, Hopital Haut-L[umlaut]av[angstrom]aque,
33076 Bordeaux, France
APStracts 2:0066E, 1995.
The action of arginine vasopressin (AVP) on cytosolic free calcium
concentration ([Ca2+]i) was studied at the single cell level in
corticotrophs cultured from pituitary adenoma fragments removed from
8 patients with Cushings disease. AVP evoked distinct [Ca2+]i
responses with regard to the tumor origin. In cells from two tumors,
AVP consistently evoked a series of characteristic elevations of
[Ca2+]i (transient pattern) which depend on Ca2+ entry. In cells from
the other tumors, AVP triggered different patterns of [Ca2+]i rise
which consisted of low amplitude, slow monophasic increases at low
AVP concentration, and of high amplitude, spike increase followed by
a sustained plateau (spike/plateau pattern) at higher concentration
of AVP. Slow monophasic increases and the spike of spike/plateau
responses were due to calcium release from internal stores whereas
the plateau is a consequence of calcium entry. These two patterns
(transient versus spike/plateau) resemble those observed in sub
-populations of corticotrophs from healthy rat pituitary glands
(Corcuff et al. J. Biol. Chem. 268:22313, 1993), suggesting that
tumorigenesis can lead in pituitary tissues to a selection rather
than alteration of AVP [Ca2+]i signals.
Received 7 November 1994; accepted in final form 20 March 1995.
APS Manuscript Number E460-4.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 19 April 1995.