Document Detail

Melatonin inhibits nitric oxide signaling by increasing PDE5 phosphorylation in coronary arteries.
MedLine Citation:
PMID:  23086989     Owner:  NLM     Status:  MEDLINE    
Melatonin inhibits nitric oxide (NO)-induced relaxation of coronary arteries. We tested the hypothesis that melatonin increases the phosphorylation of phosphodiesterase 5 (PDE5), which increases the activity of the enzyme and thereby decreases intracellular cGMP accumulation in response to NO and inhibits NO-induced relaxation. Sodium nitroprusside (SNP) and 8-Br-cGMP caused concentration-dependent relaxation of isolated coronary arteries suspended in organ chambers for isometric tension recording. In the presence of melatonin, the concentration-response curve to SNP, but not 8-Br-cGMP, was shifted to the right. The effect of melatonin on SNP-induced relaxation was abolished in the presence of the PDE5 inhibitors zaprinast and sildenafil. Melatonin markedly inhibited the SNP-induced increase in intracellular cGMP in coronary arteries, an effect that was also abolished by zaprinast. Treatment of coronary arteries with melatonin caused a nearly fourfold increase in the phosphorylation of PDE5, which increased the catalytic activity of the enzyme and thereby increased the degradation of cGMP to inactive 5'-GMP. Melatonin-induced PDE5 phosphorylation was markedly attenuated in the presence of the PKG1 inhibitors DT-2 or Rp-8-Br-PET-cGMPS and in those arteries in which PKG1 expression was first downregulated by 24-h incubation with SNP before exposure to melatonin. The selective MT(2) receptor antagonist 4-phenyl-2-propionamidotetralin completely blocked the stimulatory effect of melatonin on PDE5 phosphorylation as well as the inhibitory effect of melatonin on SNP-induced relaxation and intracellular cGMP. Thus, in coronary arteries, melatonin acts via MT(2) receptors and PKG1 to increase PDE5 phosphorylation, resulting in decreased cGMP accumulation in response to NO and impaired NO-induced vasorelaxation.
Praveen Shukla; Chengwen Sun; Stephen T O'Rourke
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2012-10-19
Journal Detail:
Title:  American journal of physiology. Heart and circulatory physiology     Volume:  303     ISSN:  1522-1539     ISO Abbreviation:  Am. J. Physiol. Heart Circ. Physiol.     Publication Date:  2012 Dec 
Date Detail:
Created Date:  2012-12-17     Completed Date:  2013-04-09     Revised Date:  2013-12-18    
Medline Journal Info:
Nlm Unique ID:  100901228     Medline TA:  Am J Physiol Heart Circ Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  H1418-25     Citation Subset:  IM    
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MeSH Terms
Coronary Vessels / metabolism*
Cyclic GMP / analogs & derivatives,  metabolism,  pharmacology
Cyclic GMP-Dependent Protein Kinases / metabolism
Cyclic Nucleotide Phosphodiesterases, Type 5 / metabolism*
Melatonin / pharmacology*
Models, Animal
Nitric Oxide / antagonists & inhibitors*,  metabolism*
Nitroprusside / pharmacology
Phosphorylation / drug effects
Receptor, Melatonin, MT2 / metabolism
Signal Transduction / drug effects*,  physiology
Vasodilation / drug effects
Grant Support
Reg. No./Substance:
0/Receptor, Melatonin, MT2; 169D1260KM/Nitroprusside; 31356-94-2/8-bromocyclic GMP; 31C4KY9ESH/Nitric Oxide; EC GMP-Dependent Protein Kinases; EC Nucleotide Phosphodiesterases, Type 5; H2D2X058MU/Cyclic GMP; JL5DK93RCL/Melatonin

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