Activation of protein kinase C stimulates cAMP phosphodiesterase in rat renal collecting tubule.
The present study was undertaken to evaluate whether protein kinase C (PKC) affects adenosine 3',5'-cyclic monophosphate phosphodiesterase (cAMP-PDIE) activity in microdissected rat renal medullary collecting tubules (MCT). Phorbol 12-myristate 13-acetate (PMA, 10(-8) M), an activator of PKC, significantly stimulated cAMP-PDIE activity in intact MCT (29.5 +/- 1.5 to 38.3 +/- 3.7 fmol.min-1.mm-1, P < 0.05) but not in the proximal straight tubule [4.7 +/- 0.8 vs. 4.8 +/- 0.8, not significant (NS)] or the medullary ascending limb of Henle's loop (20.5 +/- 2.1 vs. 22.4 +/- 2.8, NS). PMA-stimulated cAMP-PDIE activity was reversed by PKC inhibitors, staurosporine (10(-8) M) and calphostin C (10(-8) M), but not by the cyclooxygenase inhibitor, indomethacin (5 x 10(-6) M). 1,2-Dioctanoyl-sn-glycerol (50 micrograms/ml), a synthetic analogue of diacylglycerol that stimulates PKC, also increased cAMP-PDIE activity in broken-cell preparations from MCT. This stimulation was also suppressed by staurosporine (10(-8) M) and calphostin C (10(-8) M). The stimulatory effect of PMA on cAMP-PDIE activity was lost with rolipram (10(-4) M), a type IV PDIE inhibitor, whereas it was preserved with N-(6-amino-hexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride (W-7) (10(-4) M), a calmodulin inhibitor, or vinpocetin (10(-4) M), a direct inhibitor of type I PDIE. From these results, we suggest that activation of PKC specifically stimulates rolipram-sensitive cAMP-PDIE, but not the calmodulin-sensitive isozyme, in rat MCT.
Tetsuka
T
T
Division of Nephrology, Jichi Medical School, Tochigi, Japan.
Kusano
E
E
Takeda
S
S
Homma
S
S
Yoshida
I
I
Ando
Y
Y
Asano
Y
Y
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D007685:Kidney Tubules, Collecting / Q000378:metabolism*; D008297:Male; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D014018:Tissue Distribution
D011493:Protein Kinase C; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D013755:Tetradecanoylphorbol Acetate; D007213:Indomethacin