Nitric oxide‐sensitive guanylyl cyclase is the only nitric oxide receptor mediating platelet inhibition

Abstract

Summary. Background: The nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) signaling cascade is involved in the precise regulation of platelet responses. NO released from the endothelium is known to activate NO-sensitive guanylyl cyclase (NO-GC) in platelets. By the generation of cGMP and subsequent activation of cGMP-dependent protein kinase (PKG), NO-GC mediates the reduction of the intracellular calcium and inhibits platelet adhesion and aggregation. However, NO has been postulated to influence these platelet functions also via cGMP-independent mechanisms. Objective: We studied the effect of NO on platelets lacking NO-sensitive guanylyl cyclase with regards to aggregation, adhesion, calcium mobilization and bleeding time. Methods and results: Here, we show that NO signaling leading to inhibition of agonist-induced platelet aggregation is totally abrogated in platelets from mice deficient in NO-GC (GCKO). Even at millimolar concentrations none of the several different NO donors inhibited collagen-induced aggregation of GCKO platelets. In addition, NO neither affected adenosine 5¢-diphosphate (ADP)-induced adhesion nor thrombin-induced calcium release in GCKO platelets. Although the NO-induced cGMP signal transduction was totally abrogated cyclic adenosine monophosphate (cAMP) signaling was still functional; however, cGMP/cAMP crosstalk was disturbed on the level of phosphodiesterase type 3 (PDE3). These in vitro data are completed by a reduced bleeding time indicating the lack of NO effect in vivo. Conclusions: We conclude that NO-GC is the only NO receptor in murine platelets mediating the inhibition of calcium release, adhesion and aggregation: lack of the enzyme leads to disturbance of primary hemostasis.

Blockade of the purinergic P2Y 12 receptor greatly increases the platelet inhibitory actions of nitric oxide

“…It has been recently demonstrated that physiologically relevant concentrations of DEA/NONOate and other NO donors act in platelets exclusively through activation of soluble guanylyl cyclase, driving the production of cGMP (13). cGMP is an important signaling molecule with its own downstream effectors but may also act in part by influencing cAMP signaling.…”

“…NO acts by directly activating platelet guanylyl cyclase, causing an increase in intraplatelet cGMP (13). Although this cGMP pathway is distinct from the cAMP pathway that is modulated by PGI 2 and P2Y 12 , earlier studies have shown that activation of these two inhibitory pathways produces a synergistic antiplatelet effect (18).…”

“…Compared with PGI 2 , NO is less potent as an inhibitor of platelet activation (10)(11)(12)(13)(14)(15)(16)(17). NO acts by directly activating platelet guanylyl cyclase, causing an increase in intraplatelet cGMP (13).…”

cGMP-Dependent Protein Kinase in the Regulation of Cardiovascular Functions

“…Substantial evidence supports a critical role for PKG in mediating the anti-platelet aggregation action caused by cGMP elevating agents such as endothelium-derived NO (EDNO) and exogenous nitrovasodilators (Walter & Gambaryan, 2009;Dangel et al, 2010). PKG I is the predominate isoform of the enzyme in platelets.…”

Nitric oxide donor hybrid compounds as promising anticancer agents

“…In the NO/ sGC/cGMP pathway, endogenous NO synthesized by NO synthases (NOSs) activates soluble guanylate cyclase (sGC) in cells such as muscles, neurons and leukocytes. Active sGC catalyzes the synthesis of cyclic GMP (cGMP) (7). Then cGMP activates three effector molecules: the cGMP-dependent protein kinase G (PKG), cGMP-regulated phosphodiesterases, and cGMP-gated ion channels (8).…”