Phorbol ester and okadaic acid regulation of na2clk cotransport in
rabbit tracheal epithelial cells..
Liedtke, Carole M., and Linda Thomas.
Cystic Fibrosis Center, Department of Pediatrics at Rainbow Babies
& Children Hospital, and Department of Physiology & Biophysics,
Case Western Reserve University, Cleveland, OH 44106
APStracts 3:0061C, 1996.
We evaluated a role for protein kinase C (PKC) in the regulation of
rabbit tracheal epithelial NaCl(K) cotransport. Short term treatment
with phorbol 12-myristate 13-acetate (PMA) dose-dependently increased
bumetanide-sensitive Na and Cl efflux and elevated staurosporine-and
bumetanide-sensitive Na, Cl and K uptake. PMA and the [alpha]2A
-adrenergic agonist guanabenz each induced cotransport with a
stoichiometry of 2 Cl:1 Na and 2 Cl:1 Rb and elevated staurosporine
-sensitive PKC activity in cytosolic and particulate fractions.
Prolonged PMA treatment did not sustain bumetanide-sensitive 2Cl:1Na,
2Cl:1Rb transport but did block stimulation of bumetanide-sensitive
transport by PMA or guanabenz and elevation of PKC activity by PMA
and guanabenz in a particulate fraction. Cells treated with okadaic
acid exhibited a staurosporine-and bumetanide-sensitive 2Cl:1Na and
2Cl:1Rb uptake. In cultured monolayers, basolateral perfusion with
epinephrine, isoproterenol or PMA increased Isc. Basolateral
application of bumetanide reduced elevated Isc to baseline levels,
indicating a role for Cl secretory cells in a reconstituted tracheal
epithelium. Pretreatment of transmonolayer cultures with PMA
diminished the stimulatory response to epinephrine. These results
indicate that, in rabbit tracheal epithelial cells, [alpha]
-adrenergic stimulation activated Na2ClK cotransport and that PKC is a
critical effector in this process.
Received 5 June 1995; accepted in final form 7 February 1996.
APS Manuscript Number C316-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 13 March 96