Pulmonary PKG-1 is upregulated following chronic hypoxia.
Recent studies from our laboratory indicate that pulmonary vasodilatory responses to exogenous nitric oxide (NO) are attenuated following chronic hypoxia (CH) and that this NO-dependent vasodilation is mediated by cGMP. Similarly, we have demonstrated that CH attenuates vasodilatory responses to the cGMP analog 8-bromoguanosine 3',5'-cyclic monophosphate (8-BrcGMP). We hypothesized that attenuated pulmonary vasodilation to 8-BrcGMP following CH is mediated by decreased protein kinase G-1 (PKG-1) expression/activity. Therefore, we examined vasodilatory responses to 8-BrcGMP (1 microM) in isolated, saline-perfused lungs from control and CH (4 wk at barometric pressure of 380 mmHg) rats in the presence of the competitive PKG inhibitor Rp-beta-phenyl-1, N2-etheno-8-bromoguanosine 3',5'-cyclic monophosphorothionate (30 microM) or the highly specific PKG inhibitor KT-5823 (10 microM). PKG-1 expression and activity were determined in whole lung homogenates from each group, and vascular PKG-1 levels were assessed by quantitative immunohistochemistry. PKG inhibition with either Rp-8-Br-PET-cGMPS or KT-5823 diminished vasodilatory responses to 8-BrcGMP in lungs from both control and CH rats, thus indicating a role for PKG in mediating reactivity to 8-BrcGMP in each group. However, in contrast to our hypothesis, PKG-1 levels were approximately twofold greater in lungs from CH rats vs. controls, and furthermore, this upregulation was localized to the vasculature. This correlates with an increase in PKG activity following CH. We conclude that PKG-1 is involved in 8-BrcGMP-mediated vasodilation; however, attenuated pulmonary vasodilation following CH is not associated with decreased expression/activity of PKG-1.
Jernigan
Nikki L
NL
Dept. of Cell Biology and Physiology, Univ. of New Mexico Health Sciences Center, 915 Camino de Salud NE, Albuquerque, NM 87131-5218, USA. njernigan@salud.unm.edu
Walker
Benjimen R
BR
Resta
Thomas C
TC
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D002227:Carbazoles; D002908:Chronic Disease; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D017869:Cyclic GMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006976:Hypertension, Pulmonary / Q000378:metabolism / Q000503:physiopathology; D017380:Hypertrophy, Right Ventricular / Q000378:metabolism; D000860:Hypoxia / Q000378:metabolism* / Q000503:physiopathology; D007150:Immunohistochemistry; D007211:Indoles; D008168:Lung / Q000098:blood supply / Q000201:enzymology* / Q000503:physiopathology; D009569:Nitric Oxide / Q000378:metabolism; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D011086:Polycythemia / Q000378:metabolism; D011652:Pulmonary Circulation / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013873:Thionucleotides / Q000494:pharmacology; D015854:Up-Regulation; D014655:Vascular Resistance / Q000502:physiology; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology
D000470:Alkaloids; D002227:Carbazoles; D004791:Enzyme Inhibitors; D007211:Indoles; D010975:Platelet Aggregation Inhibitors; D013873:Thionucleotides; C073601:KT 5823; D015124:8-Bromo Cyclic Adenosine Monophosphate; D009569:Nitric Oxide; C055656:8-((4-chlorophenyl)thio)cyclic-3',5'-GMP; D017869:Cyclic GMP-Dependent Protein Kinases; D006152:Cyclic GMP