Upregulation of phosphodiesterase 1A1 expression is associated with the development of nitrate tolerance.
BACKGROUND
The efficacy of nitroglycerin (NTG) as a vasodilator is limited by tolerance, which develops shortly after treatment begins. In vascular smooth muscle cells (VSMCs), NTG is denitrated to form nitric oxide (NO), which activates guanylyl cyclase and generates cGMP. cGMP plays a key role in nitrate-induced vasodilation by reducing intracellular Ca(2+) concentration. Therefore, one possible mechanism for development of nitrate tolerance would be increased activity of the cGMP phosphodiesterase (PDE), which decreases cGMP levels.


RESULTS
To test this hypothesis, rats were made tolerant by continuous infusion of NTG for 3 days (10 microgram kg(-1). min(-1) SC) with an osmotic pump. Analysis of PDE activities showed an increased function of Ca(2+)/calmodulin (CaM)-stimulated PDE (PDE1A1), which preferentially hydrolyzes cGMP after NTG treatment. Western blot analysis for the Ca(2+)/CaM-stimulated PDE revealed that PDE1A1 was increased 2.3-fold in NTG-tolerant rat aortas. Increased PDE1A1 was due to mRNA upregulation as measured by relative quantitative reverse transcription-polymerase chain reaction. The PDE1-specific inhibitor vinpocetine partially restored the sensitivity of the tolerant vasculature to subsequent NTG exposure. In cultured rat aortic VSMCs, angiotensin II (Ang II) increased PDE1A1 activity, and vinpocetine blocked the effect of Ang II on decrease in cGMP accumulation.


CONCLUSIONS
Induction of PDE1A1 in nitrate-tolerant vessels may be one mechanism by which NO/cGMP-mediated vasodilation is desensitized and Ca(2+)-mediated vasoconstriction is supersensitized. Inhibiting PDE1A1 expression and/or activity could be a novel therapeutic approach to limit nitrate tolerance.
Kim
D
D
Department of Medicine, University of Rochester, Rochester, NY, USA.
Rybalkin
S D
SD
Pi
X
X
Wang
Y
Y
Zhang
C
C
Munzel
T
T
Beavo
J A
JA
Berk
B C
BC
Yan
C
C
D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000201:enzymology; D009320:Atrial Natriuretic Factor / Q000494:pharmacology; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000378:metabolism; D054677:Cyclic Nucleotide Phosphodiesterases, Type 1; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; D004305:Dose-Response Relationship, Drug; D004361:Drug Tolerance; D004790:Enzyme Induction / Q000187:drug effects; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D005996:Nitroglycerin / Q000494:pharmacology*; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010727:Phosphoric Diester Hydrolases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015854:Up-Regulation / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology; D014748:Vinca Alkaloids / Q000494:pharmacology
D007527:Isoenzymes; D020030:Nitric Oxide Donors; D010726:Phosphodiesterase Inhibitors; D012333:RNA, Messenger; D014665:Vasodilator Agents; D014748:Vinca Alkaloids; D000804:Angiotensin II; C013983:vinpocetine; D009320:Atrial Natriuretic Factor; D010727:Phosphoric Diester Hydrolases; D054677:Cyclic Nucleotide Phosphodiesterases, Type 1; D015106:3',5'-Cyclic-GMP Phosphodiesterases; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; C517384:Pde5a protein, rat; D005996:Nitroglycerin; D006152:Cyclic GMP