Downregulation of right ventricular phosphodiesterase PDE-3A mRNA and protein before the development of canine heart failure.
Phosphodiesterase III (PDE-3) inhibitors are inotropes used to treat congestive heart failure (HF). Previous studies showed PDE-3A mRNA levels were reduced in the left ventricle (LV) in dogs subjected to pacing-induced HF. The present study evaluated a time-course for RV-specific changes in PDE-3A mRNAs and proteins after pacing for 3 wk (n = 4) or in HF (4-5 wk; n = 4-6). Total RNA from LV/RV tissues was isolated for Northern analyses; cytosolic and microsomal proteins were prepared for PDE-3A immunoblots. PDE-3A mRNAs (7-8 and 10 kb) were normalized against glyceraldehyde-3-phosphodehydrogenase (GAPDH) or ribosomal 18s with similar results. PDE-3A/GAPDH ratios in 3 wk were unchanged in LV, but significantly (p < 0.05) reduced by 48% in RV vs unpaced controls (n = 8). In contrast, PDE-3A (7-8 kb)/GAPDH ratios were significantly reduced in HF by 50-59% in both ventricles. Consistent with mRNA levels, significant reductions in microsomal 135 kDa (93-96%) and cytosolic 120 kDa PDE-3A (57-69%) were seen in both ventricles in HF or in the RV at 3 wk; an LV-specific reduction (50%) in cytosolic 80 kDa PDE-3A in HF was also detected. In summary, RV-specific downregulation of PDE-3A mRNA/protein(s) at 3 wk suggests that hemodynamic rather than humoral mechanisms are responsible, and provides a molecular basis for the limited efficacy of milrinone in the progression of HF.
Smith
C J
CJ
Department of Pathology, New York Medical College, Valhalla, NY 10595, USA. carolyn_smith@nymc.edu
He
J
J
Ricketts
S G
SG
Ding
J Z
JZ
Moggio
R A
RA
Hintze
T H
TH
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3; D003600:Cytosol / Q000201:enzymology; D004195:Disease Models, Animal; D004285:Dogs; D015536:Down-Regulation / Q000235:genetics*; D005786:Gene Expression Regulation; D006333:Heart Failure / Q000201:enzymology* / Q000235:genetics / Q000503:physiopathology; D006352:Heart Ventricles / Q000201:enzymology; D007425:Intracellular Membranes / Q000201:enzymology; D008565:Membrane Proteins / Q000032:analysis; D008861:Microsomes / Q000201:enzymology; D012333:RNA, Messenger / Q000378:metabolism*; D018497:Ventricular Dysfunction, Right / Q000201:enzymology* / Q000235:genetics / Q000503:physiopathology
D008565:Membrane Proteins; D012333:RNA, Messenger; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3