Roles for redox mechanisms controlling protein kinase G in pulmonary and coronary artery responses to hypoxia.

Abstract

We previously reported that isolated endothelium-removed bovine pulmonary arteries (BPAs) contract to hypoxia associated with removal of peroxide- and cGMP-mediated relaxation. In contrast, bovine coronary arteries (BCAs) relax to hypoxia associated with cytosolic NADPH oxidation coordinating multiple relaxing mechanisms. Since we recently found that H(2)O(2) relaxes BPAs through PKG activation by both soluble guanylate cyclase (sGC)/cGMP-dependent and cGMP-independent thiol oxidation/subunit dimerization mechanisms, we investigated if these mechanisms participate in BPA contraction and BCA relaxation to hypoxia. The contraction of BPA (precontracted with 20 mM KCl) to hypoxia was associated with decreased PKG dimerization and PKG-mediated vasodilator-stimulated phosphoprotein (VASP) phosphorylation. In contrast, exposure of 20 mM KCl-precontracted endothelium-removed BCAs to hypoxia caused relaxation and increased dimerization and VASP phosphorylation. Depletion of sGC by organoid culture of BPAs with an oxidant of the sGC heme (10 μM 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one) increased aerobic force generation, decreased VASP phosphorylation, and inhibited further contraction to hypoxia and changes in VASP phosphorylation. Thiol reduction with dithiothreitol increased aerobic force in BPAs and decreased PKG dimerization, VASP phosphorylation, and the contraction to hypoxia. Furthermore, PKG-1α and sGC β(1)-subunit small interfering RNA-transfected BPAs demonstrated increased aerobic K(+) force and inhibition of further contraction to hypoxia, associated with an attenuation of H(2)O(2)-elicited relaxation and VASP phosphorylation. Thus, decreases in both a sGC/cGMP-dependent and a dimerization-dependent activation of PKG by H(2)O(2) appear to contribute to the contraction of BPAs elicited by hypoxia. In addition, stimulation of PKG activation by dimerization may be important in the relaxation of coronary arteries to hypoxia.

• Authors: Boon Hwa Neo, Sharath Kandhi, Michael S Wolin
• Journal: American journal of physiology. Heart and circulatory physiology (Am J Physiol Heart Circ Physiol) Vol. 301 Issue 6 Pg. H2295-304 (Dec 2011) ISSN: 1522-1539 [Electronic] United States
• PMID: 21926339 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Cell Adhesion Molecules
• Microfilament Proteins
• Phosphoproteins
• Receptors, Cytoplasmic and Nuclear
• Sulfhydryl Reagents
• Vasoconstrictor Agents
• vasodilator-stimulated phosphoprotein
• Hydrogen Peroxide
• Cyclic GMP-Dependent Protein Kinases
• Guanylate Cyclase
• Soluble Guanylyl Cyclase
• Cyclic GMP
• Oxygen

Topics

• Animals
• Blotting, Western
• Cattle
• Cell Adhesion Molecules (metabolism)
• Coronary Vessels (drug effects, enzymology, physiopathology)
• Cyclic GMP (metabolism)
• Cyclic GMP-Dependent Protein Kinases (genetics, metabolism)
• Enzyme Activation
• Guanylate Cyclase (genetics, metabolism)
• Hydrogen Peroxide (metabolism)
• Hypoxia (metabolism, physiopathology)
• Microfilament Proteins (metabolism)
• Oxidation-Reduction
• Oxygen (metabolism)
• Phosphoproteins (metabolism)
• Phosphorylation
• Protein Multimerization
• Pulmonary Artery (drug effects, enzymology, physiopathology)
• RNA Interference
• Receptors, Cytoplasmic and Nuclear (genetics, metabolism)
• Soluble Guanylyl Cyclase
• Sulfhydryl Reagents (pharmacology)
• Tissue Culture Techniques
• Transfection
• Vasoconstriction (drug effects)
• Vasoconstrictor Agents (pharmacology)
• Vasodilation (drug effects)