Egression of anp-stimulated cgmp in rabbit renal collecting duct
cells: abrogation of polarity by sv40 large-t.
Millul, Valerie, Dominique Prie, Monique Geniteau-Legendre, Marie
-Christine Verpont, Beatrice Baudouin, and Pierre M. Ronco.
Institut National de la Sant[acute]e et de la Recherche
M[acute]edicale U64, H[circumflex]opital Tenon, 75020 Paris ; U436,
Facult[acute]e Xavier-Bichat, 75018 Paris ; and Facult[acute]e de
Pharmacie, Chatenay-Malabry, France
APStracts 3:0017C, 1996.
Egression of ANP-stimulated cGMP was compared to that of
isoproterenol-stimulated cAMP in a rabbit collecting duct cell line
transformed with a temperature-sensitive strain of SV40. At 39.5 C
(inactivated large-T), cells exhibit major features of principal
cells whereas at 33 degrees C (functional large-T) they lose most of
their specific properties. When cells were grown on plastic at 39.5
degrees C, both cyclic nucleotides were predominantly released
extracellularly via probenecid-sensitive carriers. Probenecid (3 mM)
reduced by 84 % and 70 % the ratios of extracellular cGMP and cAMP,
respectively. The amount of extracellular cGMP or cAMP was linearly
correlated with the time integral of the intracellular cyclic
nucleotide, suggesting first-order kinetics. The apparent first-order
rate constant (k) was 6-fold greater for cGMP (0.139 +/- 0.037 min-1,
n = 3) than for cAMP (0.022 +/- 0.003, n = 3). IBMX markedly
inhibited extrusion of cGMP (k = 0.022 +/- 0.003 min-1) whereas that
of cAMP was unchanged. When cells were grown on filters at 39.5
degrees C, both nucleotides were predominantly released in the apical
medium, but with a greater polarity for cGMP (83 +/- 4%, n = 6) than
for cAMP (60 +/- 6%, n = 3) and a prevailing apical localization of
the probenecid-sensitive carrier. Activation of SV40 large-T at 33 C
did not alter cyclic nucleotide transport characteristics but
abolished the polarity of probenecid-sensitive cyclic nucleotide
extrusion. These results suggest a physiological role for luminal
cGMP in the rabbit collecting duct, and a specific effect of large-T
on the probenecid- sensitive carrier polarity.
Received 13 June 1995; accepted in final form 9 October 1995.
APS Manuscript Number C336-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 25 January 96