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Does EDRF/NO regulate its own release by increasing endothelial cyclic GMP?
1Department of Clinical Pharmacology, Hannover Medical School, FRG.
Basic Research in Cardiology
|January 1, 1991
Summary
Endothelial-derived relaxing factor/nitric oxide (EDRF/NO) release was assessed using a bioassay. Cyclic guanosine monophosphate (cGMP) levels in endothelial cells do not influence EDRF/NO production or release.
Area of Science:
- Cardiovascular Biology
- Cell Signaling
- Biochemistry
Background:
- Endothelial-derived relaxing factor (EDRF), now identified as nitric oxide (NO), plays a crucial role in vascular homeostasis.
- The signaling pathways regulating EDRF/NO synthesis and release are complex and involve intracellular messengers.
- Cyclic guanosine monophosphate (cGMP) is a key second messenger in NO-mediated signaling, but its role in regulating EDRF/NO production itself is not fully understood.
Purpose of the Study:
- To investigate the relationship between intracellular cyclic guanosine monophosphate (cGMP) levels and the release of endothelial-derived relaxing factor/nitric oxide (EDRF/NO) from bovine aortic endothelial cells.
- To determine if elevated cGMP levels within endothelial cells influence the synthesis or release of EDRF/NO.
Main Methods:
- Utilized a bioassay system employing rat fetal lung fibroblasts (RFL-6 cells) with high soluble guanylyl cyclase activity to detect EDRF/NO.
- Stimulated EDRF/NO release from bovine aortic endothelial cells using bradykinin and Ca2+ ionophore A23187.
- Measured intracellular cGMP levels in both endothelial cells and RFL-6 cells.
- Employed inhibitors of EDRF/NO synthesis (NG-L-arginine) and soluble guanylyl cyclase (methylene blue) to validate the bioassay.
Main Results:
- Bovine aortic endothelial cells released a substance that significantly increased cGMP in RFL-6 cells, confirming EDRF/NO activity.
- Bradykinin and A23187 stimulated EDRF/NO release and were accompanied by a two-fold increase in endothelial cell cGMP.
- Pharmacological elevation of endothelial cGMP levels using atrial natriuretic peptide or sodium nitroprusside did not affect basal or stimulated EDRF/NO release.
Conclusions:
- Intracellular cyclic guanosine monophosphate (cGMP) levels in bovine aortic endothelial cells do not exert feedback control on the formation or release of endothelial-derived relaxing factor/nitric oxide (EDRF/NO).
- The study provides evidence against a direct autocrine or paracrine regulatory role of cGMP on EDRF/NO production in this cellular model.