Cyclic 3',5'-nucleotide diesterases in dynamics of cAMP and cGMP in rat collecting duct cells.
We studied cyclic 3',5'-nucleotide phosphodiesterase (PDE) isozymes and their role in adenosine 3',5'-cyclic monophosphate (cAMP) and cGMP metabolism in a rat inner medullary collecting duct (IMCD) cell line. The homogenized and fractionated IMCD cells of cAMP-PDE and all of cGMP-PDE activity were found in the cytosol. The majority of cytosolic cAMP-PDE (greater than 50%) was isozyme PDE-IV; the Ca(2+)-calmodulin-sensitive PDE-I was present only in cytosol. Preincubation of IMCD cells with PDE-IV inhibitor rolipram markedly (5x) enhanced levels of cAMP both basal and in the presence of [Arg8]vasopressin (AVP). Cilostamide (for PDE-III) or vinpocetine had no effect, whereas PDE-I inhibitor 8-methoxymethyl-3-isobutyl-1-methylxanthine (8-MeoM-IBMX) enhanced AVP-dependent cAMP levels. Exposure of IMCD cells to 2 microM ionomycin decreased both basal and AVP-stimulated cAMP. Depletion of Ca2+ by preincubation of IMCD cells in the Ca(2+)-free medium with ethylene glycol-bis (beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid markedly enhanced the stimulatory response of cAMP to AVP, and addition of 8-MeoM-IBMX further enhanced the AVP response. The levels of cGMP, basal or in response to atriopeptin (ANP), were not affected by PDE-V inhibitor zaprinast, but both inhibitors of PDE-I, 8-MeoM-IBMX and vinpocetine, increased basal cGMP, and 8-MeoM-IBMX also increased cGMP levels enhanced by ANP. The depletion of Ca2+ from IMCD cells alone had no effect on cGMP levels, but effects of 8-MeoM-IBMX and vinpocetine on the ANP-stimulated cGMP levels were enhanced.(ABSTRACT TRUNCATED AT 250 WORDS)
Yamaki
M
M
Department of Physiology and Biophysics, Mayo Clinic, Rochester, Minnesota 55905.
McIntyre
S
S
Rassier
M E
ME
Schwartz
J H
JH
Dousa
T P
TP
D015087:2',3'-Cyclic-Nucleotide Phosphodiesterases / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology; D000242:Cyclic AMP / Q000378:metabolism*; D006152:Cyclic GMP / Q000378:metabolism*; D003600:Cytosol / Q000201:enzymology; D007527:Isoenzymes / Q000378:metabolism; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000378:metabolism*; D051381:Rats
D007527:Isoenzymes; D000242:Cyclic AMP; D015087:2',3'-Cyclic-Nucleotide Phosphodiesterases; D006152:Cyclic GMP