TY - JOUR
T1 - Compartmentalization of cardiac β-adrenergic inotropy modulation by phosphodiesterase type 5
AU - Takimoto, Eiki
AU - Belardi, Diego
AU - Tocchetti, Carlo G.
AU - Vahebi, Susan
AU - Cormaci, Gianfrancesco
AU - Ketner, Elizabeth A.
AU - Moens, An L.
AU - Champion, Hunter C.
AU - Kass, David A.
PY - 2007/4
Y1 - 2007/4
N2 - BACKGROUND - Recent cell-based studies have found that cGMP synthesis and hydrolysis by phosphodiesterase (PDE) appear compartmentalized, with nitric oxide synthase-derived and/or PDE type 5 (PDE-5)-hydrolyzable cGMP undetected at the sarcolemmal membrane in contrast to cGMP stimulated by natriuretic peptide. In the present study, we determine the functional significance of such compartments with a comparison of β-adrenergic modulation by PDE-5 inhibition to that of natriuretic peptide stimulation in both cardiomyocytes and intact hearts. The potential role of differential cGMP and protein kinase G stimulation by these 2 modulators was also studied. METHODS AND RESULTS - Intact C57/BL6 mouse hearts were studied with pressure-volume analysis, and adult isolated myocytes were studied with fluorescence microscopy. PDE-5 inhibition with 0.1 to 1 μmol/L sildenafil (SIL) suppressed isoproterenol (ISO)-stimulated contractility, whereas 10 μmol/L atrial natriuretic peptide (ANP) had no effect. ISO suppression by SIL was prevented in cells pretreated with a protein kinase G inhibitor. Surprisingly, myocardial cGMP changed little with SIL+ISO yet rose nearly 5-fold with ANP, whereas protein kinase G activation (vasodilator-stimulated protein phosphorylation; ELISA assay) displayed the opposite: increased with SIL+ISO but unaltered by ANP+ISO. PDE-5 and ANP compartments were functionally separated, as inhibition of nitric oxide synthase by N-nitro-L-arginine methyl ester eliminated antiadrenergic effects of SIL, yet this was not restorable by co-stimulation with ANP. CONCLUSIONS - Regulation of cardiac β-adrenergic response by cGMP is specifically linked to a nitric oxide-synthesis/PDE-5-hydrolyzed pool signaling via protein kinase G. Natriuretic peptide stimulation achieves greater detectable increases in cGMP but not protein kinase G activity and does not modulate β-adrenergic response. Such disparities likely contribute to differential cardiac regulation by drugs that modulate cGMP synthesis and hydrolysis.
AB - BACKGROUND - Recent cell-based studies have found that cGMP synthesis and hydrolysis by phosphodiesterase (PDE) appear compartmentalized, with nitric oxide synthase-derived and/or PDE type 5 (PDE-5)-hydrolyzable cGMP undetected at the sarcolemmal membrane in contrast to cGMP stimulated by natriuretic peptide. In the present study, we determine the functional significance of such compartments with a comparison of β-adrenergic modulation by PDE-5 inhibition to that of natriuretic peptide stimulation in both cardiomyocytes and intact hearts. The potential role of differential cGMP and protein kinase G stimulation by these 2 modulators was also studied. METHODS AND RESULTS - Intact C57/BL6 mouse hearts were studied with pressure-volume analysis, and adult isolated myocytes were studied with fluorescence microscopy. PDE-5 inhibition with 0.1 to 1 μmol/L sildenafil (SIL) suppressed isoproterenol (ISO)-stimulated contractility, whereas 10 μmol/L atrial natriuretic peptide (ANP) had no effect. ISO suppression by SIL was prevented in cells pretreated with a protein kinase G inhibitor. Surprisingly, myocardial cGMP changed little with SIL+ISO yet rose nearly 5-fold with ANP, whereas protein kinase G activation (vasodilator-stimulated protein phosphorylation; ELISA assay) displayed the opposite: increased with SIL+ISO but unaltered by ANP+ISO. PDE-5 and ANP compartments were functionally separated, as inhibition of nitric oxide synthase by N-nitro-L-arginine methyl ester eliminated antiadrenergic effects of SIL, yet this was not restorable by co-stimulation with ANP. CONCLUSIONS - Regulation of cardiac β-adrenergic response by cGMP is specifically linked to a nitric oxide-synthesis/PDE-5-hydrolyzed pool signaling via protein kinase G. Natriuretic peptide stimulation achieves greater detectable increases in cGMP but not protein kinase G activity and does not modulate β-adrenergic response. Such disparities likely contribute to differential cardiac regulation by drugs that modulate cGMP synthesis and hydrolysis.
KW - Catecholamines
KW - Contractility
KW - Cyclic GMP
KW - Myocytes
KW - Natriuretic peptides
KW - Nitric oxide synthase
KW - Phosphodiesterases, type 5
UR - http://www.scopus.com/inward/record.url?scp=34247488713&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=34247488713&partnerID=8YFLogxK
U2 - 10.1161/CIRCULATIONAHA.106.643536
DO - 10.1161/CIRCULATIONAHA.106.643536
M3 - Article
C2 - 17420342
AN - SCOPUS:34247488713
SN - 0009-7322
VL - 115
SP - 2159
EP - 2167
JO - Circulation
JF - Circulation
IS - 16
ER -