Type II cAMP-dependent protein kinase regulates electrogenic ion transport in rabbit collecting duct.
cAMP mediates many of the effects of vasopressin, prostaglandin E2, and beta-adrenergic agents upon salt and water transport in the renal collecting duct. The present studies examined the role of cAMP-dependent protein kinase (PKA) in mediating these effects. PKA is a heterotetramer comprised of two regulatory (R) subunits and two catalytic (C) subunits. The four PKA isoforms may be distinguished by their R subunits that have been designated RIalpha, RIbeta, RIIalpha, and RIIbeta. Three regulatory subunits, RIalpha, RIIalpha, and RIIbeta, were detected by immunoblot and ribonuclease protection in both primary cultures and fresh isolates of rabbit cortical collecting ducts (CCDs). Monolayers of cultured CCDs grown on semipermeable supports were mounted in an Ussing chamber, and combinations of cAMP analogs that selectively activate PKA type I vs. PKA type II were tested for their effect on electrogenic ion transport. Short-circuit current (Isc) was significantly increased by the PKA type II-selective analog pairs N6-monobutyryl-cAMP plus 8-(4-chlorophenylthio)-cAMP or N6-monobutyryl-cAMP plus 8-chloro-cAMP. In contrast the PKA type I-selective cAMP analog pair [N6-monobutyryl-cAMP plus 8-(6-aminohexyl)-amino-cAMP] had no effect on Isc. These results suggest PKA type II is the major isozyme regulating electrogenic ion transport in the rabbit collecting duct.
Qi
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Division of Nephrology, Departments of Medicine and Molecular Physiology and Biophysics, Veterans Affairs Medical Center, and Vanderbilt University School of Medicine, Nashville, Tennessee 37212, USA.
Hao
C M
CM
Salter
K
K
Redha
R
R
Breyer
M D
MD
D000818:Animals; D001692:Biological Transport / Q000502:physiology; D002478:Cells, Cultured; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000502:physiology*; D053938:DNA Fragmentation / Q000502:physiology; D018076:DNA, Complementary / Q000235:genetics; D004594:Electrophysiology; D005260:Female; D007477:Ions; D007527:Isoenzymes / Q000235:genetics / Q000502:physiology*; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000378:metabolism*; D008969:Molecular Sequence Data; D011817:Rabbits
D018076:DNA, Complementary; D007477:Ions; D007527:Isoenzymes; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases