Role of phosphodiesterase ii in the cross-talk between cyclic gmp
and cyclic amp in human neuroblastoma nb-ok-1 cells.
Delporte, Christine, Piotr Poloczek, and Jacques Winand.
Department of Biochemistry and Nutrition, Medical School,
Universit[acute]e Libre de Bruxelles, Building G/E - CP 611, 808
Route de Lennik, B-1070 Brussels, Belgium
APStracts 2:0251C, 1995.
Cyclic nucleotides levels and cyclic nucleotide phosphodiesterase
(PDE) activities were measured in human neuroblastoma NB-OK-1 cells
possessing ANP receptors of the A type and PACAP-preferring
receptors. cAMP and cGMP degradation were interrelated since the
increase in cGMP, induced by ANP-(99-126), stimulated the hydrolysis
of cAMP by PDE isoenzyme II. In intact NB-OK-1 cells, the levels of
cAMP and cGMP attained in the presence of, respectively, 1 nM PACAP
-(1-27) and 10 nM ANP-(99-126), and in the absence or presence of
phosphodiesterase inhibitors, strongly suggested that cAMP hydrolysis
was mainly achieved by isoenzyme IV, and to a lesser extent by
isoenzymes I, II and III, while cGMP was degraded by isoenzymes I,
II, III and V. More than half of total cAMP- and cGMP-hydrolyzing
activities was present in the membrane-bound fraction. Cyclic
nucleotide phosphodiesterase activities separated by anion-exchange
chromatography showed that isoenzymes III and IV were mainly present
in the membrane fraction while isoenzymes I, II and V were in the
cytosolic fraction.
Received 19 October 1994; accepted in final form 27 June 1995.
APS Manuscript Number C626-4.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 18 July 1995.