PubMed Health⌕ Search

Biomedical subjects

Wolfgang Schaper

Publications and source records attributed to Wolfgang Schaper.

At least 19 recordsLinked to original sources
PubMed2006

The range of adaptation by collateral vessels after femoral artery occlusion.

Natural adaptation to femoral artery occlusion in animals by collateral artery growth restores only approximately 35% of adenosine-recruitable maximal conductance (C(max)) probably because initially elevated fluid shear stress (FSS) quickly normalizes. We tested the hypothesis whether this deficit can be mended by artificially increasing FSS or whether anatomical restraints prevent complete restitution. We chronically increased FSS by draining the collateral flow directly into the venous system by a side-to-side anastomosis between the distal stump of the occluded femoral artery and the accompanying vein. After reclosure of the shunt collateral flow was measured at maximal vasodilatation. C(max) reached 100% already at day 7 and had, after 4 weeks, surpassed (2-fold) the C(max) of the normal vasculature before occlusion. Expression profiling showed upregulation of members of the Rho-pathway (RhoA, cofilin, focal adhesion kinase, vimentin) and the Rho-antagonist Fasudil markedly inhibited arteriogenesis. The activities of Ras and ERK-1,-2 were markedly increased in collateral vessels of the shunt experiment, and infusions of L-NAME and L-NNA strongly inhibited MAPK activity as well as shunt-induced arteriogenesis. Infusions of the peroxinitrite donor Sin-1 inhibited arteriogenesis. The radical scavengers urate, ebselen, SOD, and catalase had no effect. We conclude that increased FSS can overcome the anatomical restrictions of collateral arteries and is potentially able to completely restore maximal collateral conductance. Increased FSS activates the Ras-ERK-, the Rho-, and the NO- (but not the Akt-) pathway enabling collateral artery growth.

Adaptation, Physiological↗
PubMed2006

Critical function of Bmx/Etk in ischemia-mediated arteriogenesis and angiogenesis.

Bmx/Etk non-receptor tyrosine protein kinase has been implicated in endothelial cell migration and tube formation in vitro. However, the role of Bmx in vivo is not known. Bmx is highly induced in the vasculature of ischemic hind limbs. We used both mice with a genetic deletion of Bmx (Bmx-KO mice) and transgenic mice expressing a constitutively active form of Bmx under the endothelial Tie-2 enhancer/promoter (Bmx-SK-Tg mice) to study the role of Bmx in ischemia-mediated arteriogenesis/angiogenesis. In response to ischemia, Bmx-KO mice had markedly reduced, whereas Bmx-SK-Tg mice had enhanced, clinical recovery, limb perfusion, and ischemic reserve capacity when compared with nontransgenic control mice. The functional outcomes in these mice were correlated with ischemia-initiated arteriogenesis, capillary formation, and vessel maturation as well as Bmx-dependent expression/activation of TNF receptor 2- and VEGFR2-mediated (TNFR2/VEGFR2-mediated) angiogenic signaling in both hind limb and bone marrow. More importantly, results of bone marrow transplantation studies showed that Bmx in bone marrow-derived cells plays a critical role in the early phase of ischemic tissue remodeling. Our study provides the first demonstration to our knowledge that Bmx in endothelium and bone marrow plays a critical role in arteriogenesis/angiogenesis in vivo and suggests that Bmx may be a novel target for the treatment of vascular diseases such as coronary artery disease and peripheral arterial disease.

Animals↗
PubMed2006

Enhanced arteriogenesis in mice overexpressing erythropoietin.

After permanent occlusion of the femoral artery, the survival of ischemic limb tissue depends on collateral artery growth (arteriogenesis). In previous work, we have shown that shear stress triggers arteriogenesis. To test whether increased shear stress results in enhanced arteriogenesis, we compared arteriogenesis in transgenic mice overexpressing erythropoietin (EPO), which possessed increased blood viscosity through the higher hematocrit (thereby providing increased shear stress), with wild-type mice. The right femoral artery was occluded proximal to the origin of the arteria poplitea. Distal blood flow was assessed by laser Doppler imaging, and the growth and remodeling of collateral arteries was examined by light and electron microscopy and morphometry. After occlusion of the femoral artery, EPO mice demonstrated enhanced arteriogenesis: their collateral arteries developed a 1.7-fold diameter and a 2-fold wall thickness compared with wild-type. However, the blood flow recovery in EPO mice was markedly retarded. Structural remodeling and growth of collateral arteries was markedly enhanced in EPO mice, presumably as a result of increased blood viscosity and shear stress.

Animals↗
PubMed2006

Impact of mouse strain differences in innate hindlimb collateral vasculature.

OBJECTIVE: To assess the importance of genetic background for collateral artery development. METHODS AND RESULTS: C57BL/6, BALB/c and 129S2/Sv mice were studied after femoral artery ligation by laser Doppler imaging, visible light oximetry, time-of-flight-magnetic resonance imaging, and treadmill testing; C57BL/6 and BALB/c also underwent electron paramagnetic resonance (EPR) oximetry, x-ray angiography, and histology. C57BL/6 had the least initial distal ischemia and most complete recovery. BALB/c had the most severe initial ischemia and poorest recovery. BALB/c had some vasodilatory reserve in their ligated limbs not seen in the other strains at 3 weeks. By in vivo TOF-magnetic resonance angiography, C57BL/6 had larger preexistent and developed collaterals. By x-ray angiography, C57BL/6 had a higher collateral-dependent filling score and number of visible collaterals immediately after femoral ligation and a higher number of visible collaterals at 1 week but not at 4 weeks. EPR oximetry and histology revealed hypoxia and tissue damage in regions of collateral growth of BALB/c but not C57BL/6 mice. In C57BL/6 BrdUrd uptake in the thigh was limited to larger vessels and isolated perivascular cells. Proliferative activity in collateral arterioles was similar in both strains. CONCLUSIONS: Genetic differences in preexistent collateral vasculature can profoundly affect outcome and milieu for compensatory collateral artery growth after femoral artery occlusion.

Animals↗
PubMed2006

MEK hyperphosphorylation coincides with cell cycle shut down of cultured smooth muscle cells.

Smooth muscle cells (SMCs) form the backbone of arteries and their proliferation hallmarks collateral vessel growth, a process termed arteriogenesis, as well as pathogenic responses such as restenosis. Since signaling pathways in SMCs are the main targets for therapeutic interventions, we aimed to determine how and to what extent the activation of the ubiquitous MEK-ERK signaling pathway correlates with important in vivo phenomena such as dedifferentiation, nuclear activation and proliferation of SMCs. Specificity of this pathway was monitored using MEK inhibitors UO126 and PD98059 in platelet derived growth factor-AB (PDGF-AB)- and fibroblast growth factor-2 (FGF-2)-stimulated SMCs. PDGF-AB induced a rapid MEK activation followed by phosphorylation of the MEK substrates ERK1/2 while FGF-2 showed a less pronounced and delayed activation. Both growth factors triggered a marked phosphorylation of c-Myc and expression of Egr1. Pretreatment with MEK inhibitors suppressed the activation of the ERK cascade, abolished the down-regulation of desmin and led to cell cycle arrest. However, the reversibility of p27Kip1 down-regulation by UO126 was mainly observed after PDGF-AB stimulation, indicating MEK independent p27Kip1 down-regulation by FGF-2. Surprisingly, treatment of SMCs with UO126 or PD98059 increased the level of MEK phosphorylation in a dose dependent manner at serine residues 217/221 in the presence as well as in the absence of both growth factors. Our results strongly imply that depending on the environmental context phosphorylation of serines 217/221 serves as an "on" as well as an "off " switch.

Animals↗
PubMed2005

START Trial: a pilot study on STimulation of ARTeriogenesis using subcutaneous application of granulocyte-macrophage colony-stimulating factor as a new treatment for peripheral vascular disease.

BACKGROUND: Granulocyte-macrophage colony-stimulating factor (GM-CSF) was recently shown to increase collateral flow index in patients with coronary artery disease. Experimental models showed beneficial effects of GM-CSF on collateral artery growth in the peripheral circulation. Thus, in the present study, we evaluated the effects of GM-CSF in patients with peripheral artery disease. METHODS AND RESULTS: A double-blinded, randomized, placebo-controlled study was performed in 40 patients with moderate or severe intermittent claudication. Patients were treated with placebo or subcutaneously applied GM-CSF (10 microg/kg) for a period of 14 days (total of 7 injections). GM-CSF treatment led to a strong increase in total white blood cell count and C-reactive protein. Monocyte fraction initially increased but thereafter decreased significantly as compared with baseline. Both the placebo group and the treatment group showed a significant increase in walking distance at day 14 (placebo: 127+/-67 versus 184+/-87 meters, P=0.03, GM-CSF: 126+/-66 versus 189+/-141 meters, P=0.04) and at day 90. Change in walking time, the primary end point of the study, was not different between groups. No change in ankle-brachial index was found on GM-CSF treatment at day 14 or at day 90. Laser Doppler flowmetry measurements showed a significant decrease in microcirculatory flow reserve in the control group (P=0.03) and no change in the GM-CSF group. CONCLUSIONS: The present study does not support the use of GM-CSF for treatment of patients with moderate or severe intermittent claudication. Issues that need to be addressed are dosing, the selection of patients, and potential differences between GM-CSF effects in the coronary and the peripheral circulation.

Angioplasty, Balloon↗
PubMed2005

Transforming growth factor-beta1 downregulates beating frequency and remodeling of cultured rat adult cardiomyocytes.

We have observed increased levels of transforming growth factor-beta1 (TGF-beta1) in human hibernating myocardium (HM). Impaired ventricular function in HM is known to be restored to normal following revascularization implying that myocardial structure in HM is to a certain degree preserved. We have therefore tested whether TGF-beta1 can imitate features of HM by reducing the number and frequency of beating cells (chronotropism) and structural remodeling of cultured adult rat cardiomyocytes (ARC), thus saving substrate, energy, and oxygen. Parameters measured were cell size, protein synthesis, protein degradation, protein content, myofibrillogenesis, and chronotropism. ARC were stimulated for 6 days with sera from patients with coronary heart disease, as this period led to a maximum response of cells. An increase of 90% in cell surface area following such treatment was reduced to a 20% increase of the original size by TGF-beta1. Concomitantly, the rate of protein synthesis dropped from 3.6-fold to 2.4-fold, and myofibrillogenesis was reduced. TGF-beta1 downregulated both the number of contracting cells from 81% to 10% and the frequency from 52 to nine beats per minute. However, TGF-beta1 treatment did not reduce the augmentation of protein content (1.28-fold versus 1.25-fold) indicating that protein degradation was also inhibited. Similar results were obtained with serum from healthy volunteers. The effects of TGF-beta1 were reversible. We conclude that TGF-beta1 constrains protein turnover and beating activity in underperfused myocardium, thus mediating protection by adapting myocytes to shortages in blood supply.

Animals↗
PubMed2005

Preconditioning of arteriogenesis.

OBJECTIVE: Last decade, the shear stress caused by increased blood flow in collateral circulation after occlusion of main artery was recognized as a trigger of vascular remodeling and collateral growth. The goal of this study was to differentiate whether the on-going increased blood flow is necessary for the vascular remodeling or the remodeling, once in progress, develops independently of flow. METHODS: Femoral artery occlusion was performed in C57B1/6 mice. After 1-3 days, the ligature was removed and normal limb perfusion was re-established, monitored by laser Doppler Imaging (LDI). Two weeks after the first occlusion, both femoral arteries were re-occluded to compare collateral growth on the "naive" and "preconditioned" sides. After perfusion fixation, ultrastructural studies and morphometry of the collateral vessels were performed. RESULTS: Blood flow fell after occlusion to about 15% of control levels and recovered to about 40% by day 3. The reperfusion normalized sustainable blood flow. After the second occlusion, blood flow on both sides fell again to about 15% but recovered to 70% in the "preconditioned" compared to 40% in the "naive" side during the following 3 days. 5-Bromo-2'-desoxy-uridine (BrdU) administered during reperfusion was detected mainly in the neointima that, in many cases, had markedly narrowed the lumen. Two to three days after re-occlusion, a statistically significant lumen enlargement on the "preconditioned" side was observed, while neointima disappeared. CONCLUSION: Cellular proliferation and remodeling of collateral arteries were induced by short period of increased blood flow (occlusion of the femoral artery) but realized mostly during the low blood flow (reperfusion of the femoral artery). The neointima developing as a result of this remodeling can be recruited as a functional part of the arterial wall if the collateral perfusion increases as a result of repetitive occlusion of the femoral artery. The "medialization" of the neointima might cause the observed quicker gain of collateral lumen diameter and conductance, saving distal muscle tissue from the ischemia.

Animals↗
PubMed2005

Dipyridamole, an underestimated vascular protective drug.

Dipyridamole, developed almost half a century ago, acts by inhibiting nucleoside transport, which increases adenosine levels leading to inhibition of platelet aggregation and vasodilatation mainly in the coronary tree. It is a vaso-protective drug with proven efficacy in the prevention of strokes. Adenosine receptor 2 inhibitory purines, ubiquitously available in food and drink, inhibit the vasomotor effects of dipyridamole but not its action on platelet aggregation. This and the slow build-up of blood levels of dipyridamole after oral application may explain why incidents of drug-induced angina ("coronary steal") were never reported in the prevention trials. The prevention of arterial thrombosis and the positive remodeling of the arterial system (arteriogenesis) by elevated blood flows suggest that dipyridamole may be able to halt the progression of organ manifestations of atherosclerosis. Clinical trials for the secondary prevention of vascular occlusions in other vascular beds should be encouraged.

Adenosine↗
PubMed2005

H2O2 induces paracellular permeability of porcine brain-derived microvascular endothelial cells by activation of the p44/42 MAP kinase pathway.

In vivo, pathological conditions such as ischemia and ischemia/reperfusion are known to damage the blood-brain barrier (BBB) leading to the development of vasogenic brain edema. Using an in vitro model of the BBB, consisting of brain-derived microvascular endothelial cells (BMEC), it was demonstrated that hypoxia-induced paracellular permeability was strongly aggravated by reoxygenation (H/R), which was prevented by catalase suggesting that H2O2 is the main mediator of the reoxygenation effect. Therefore, mechanisms leading to H2O2-induced hyperpermeability were investigated. N-acetylcysteine and suramin and furthermore usage of a G protein antagonist inhibited H202 effects suggesting that activation of cell surface receptors coupled to G proteins may mediate signal initiation by H2O2. Further, H2O2 activated phospholipase C (PLC) and increased the intracellular Ca2+ release because U73122, TMB-8, and the calmodulin antagonist W7 inhibited H2O2-induced hyperpermeability. H2O2 did not activate protein kinase C (PKC), nitric-oxide synthase (NOS), and phosphatidyl-inositol-3 kinase (PI3-K/Akt). Inhibition of the extracellular signal-regulated kinase (ERK1/ERK2 or p44/42 MAPK), but not of the p38 and of the c-jun NH2-terminal kinase (JNK), inhibited hyperpermeability by H2O2 and H/R completely. Corresponding to H2O2- and H/R-induced permeability changes the phosphorylation of the p44/42 MAP kinase was inhibited by the specific MAP kinase inhibitor PD98059 and by TMB-8 and W7. Paracellular permeability changes by H2O2 correlated to changes of the localization of the tight junction (TJ) proteins occludin, zonula occludens 1 (ZO-1), and zonula occludens 2 (ZO-2) which were prevented by blocking the p44/p42 MAP kinase activation. Results suggest that H2O2 is the main inducer of H/R-induced permeability changes. The hyperpermeability is caused by activation of PLC via receptor activation leading to the intracellular release of Ca2+ followed by activation of the p44/42 MAP kinase and paracellular permeability changes mediated by changes of the localization of TJ proteins.

Animals↗
PubMed2005

Arteriogenic growth factors, chemokines and proteases as a prerequisite for arteriogenesis.

Frequently, patients with ischemic vascular diseases have developed collateral blood vessels bypassing areas of arterial obstructions. This may support maintenance of organ function and prevent mortality. Mechanisms of collateral artery growth differ from angiogenic capillary growth. Therefore, the term "arteriogenesis" was introduced. The distinct processes contributing to arteriogenesis are controlled by a complex interplay between cellular and molecular factors. The early mechanism includes endothelial cell activation by physical forces, release of chemokines, attraction of blood leukocytes to the collateral vessel wall followed by their adhesion and subsequent transmigration. The proliferation and remodeling phase is characterized by the release of growth factors and proteases, mediating digestion of the external elastic lamina and extracellular matrix and mediating proliferation of vascular wall cells. Maturation of the collateral vessel wall is concluded by the rearrangement of wall cells and a recovery of extracellular structures, resulting in functional arteries with the ability to markedly contribute to blood supply to the affected organ. This review will address the role of chemotactic factors, growth factors and proteases during collateral artery growth.

Animals↗
PubMed2005

The art of arteriogenesis.

The identification of collateral artery growth (arteriogenesis) as the only mechanism to compensate for the loss of an occluded artery forced us to define the mechanisms responsible for this type of vessel growth. To achieve this, a variety of coronary as well as peripheral models of arteriogenesis have been developed. Based on these studies it is obvious that arteriogenesis obeys different mechanisms than angiogenesis, the sprouting of capillaries. Upon occlusion of an artery, the blood flow is redirected into preexisting arteriolar anastomoses that experience increased mechanical forces such as shear stress and circumferential wall stress. The endothelium of the arteriolar connections is then activated, resulting in an increased release of monocyte-attracting proteins as well as an upregulation of adhesion molecules. Upon adherence and extravasation, monocytes promote arteriogenesis by supplying growth factors and cytokines that bind to receptors that are expressed on vascular cells within a limited time frame. Animal studies evidenced that factors, such as monocyte chemoattractant protein-1, granulocyte-monocyte colony-stimulating factor, or transforming growth factor-beta1, that either attract or prolong the lifetime of monocytes efficiently enhance collateral artery growth, an effect that was seen only to a minor degree after application of a single growth factor. Bone marrow-derived stems cells and endothelial progenitor cells do not incorporate in growing arteries but, rather, function as supporting cells. Complete elucidation of the mechanisms of arteriogenesis may lead to efficacious therapies counteracting the devastating consequences of vascular occlusive diseases.

Animals↗
PubMed2004

Influence of mechanical, cellular, and molecular factors on collateral artery growth (arteriogenesis).

Growth of collateral blood vessels (arteriogenesis) is potentially able to preserve structure and function of limbs and organs after occlusion of a major artery. The success of the remodeling process depends on the following conditions: (1) existence of an arteriolar network that connects the preocclusive with the postocclusive microcirculation; (2) activation of the arteriolar endothelium by elevated fluid shear stress; (3) invasion (but not incorporation) of bone marrow-derived cells; and (4) proliferation of endothelial and smooth muscle cells. Most organs of most mammals including man can rely on the existence of interconnecting arterioles in most organs and tissues with heart being the exception in rodents and pigs. Arterial occlusion lowers the pressure in the distal vasculature thereby creating a pressure gradient favoring increased flow through preexisting collaterals. This increases fluid shear stress leading to endothelial activation with cellular edema, upregulation of adhesion molecules, mitogenic-, thrombogenic-, and fibrinolytic factors, leading to monocyte invasion with matrix digestion. Smooth muscle cells migrate and proliferate and the vessel enlarges under the influence of increasing circumferential wall stress. Growth factors involved belong to the FGF family and signaling proceeds via the Ras/Raf- and the Rho cascades. Increases in vascular radius and wall thickness restore fluid shear stress and circumferential wall stress to normal levels and growth stops. Although increases in collateral vessel size are very substantial their maximal conductance amounts to only 40% of normal. Forced increases in FSS can reach almost 100%.

Animals↗
PubMed2004

Elevated fluid shear stress enhances postocclusive collateral artery growth and gene expression in the pig hind limb.

OBJECTIVE: The role of fluid shear stress (FSS) in collateral vessel growth remains disputed and prospective in vivo experiments to test its morphogenic power are rare. Therefore, we studied the influence of FSS on arteriogenesis in a new model with extremely high levels of collateral flow and FSS in pig and rabbit hind limbs. METHODS AND RESULTS: A side-to-side anastomosis was created between the distal stump of one of the bilaterally occluded femoral arteries with the accompanying vein. This clamps the collateral reentry pressure at venous levels and increases collateral flow, which is directed to a large part into the venous system. This decreases circumferential wall stress and markedly increases FSS. One week after anastomosis, angiographic number and size of collaterals were significantly increased. Maximal collateral flow exceeded by 2.3-fold that obtained in the ligature-only hind limb. Capillary density increased in lower leg muscles. Immunohistochemistry revealed augmented proliferative activity of endothelial and smooth muscle cells. Intercellular adhesion molecule-1 and vascular cell adhesion molecule (VCAM)-1 were upregulated, and monocyte invasion was markedly increased. In 2-dimensional gels, actin-regulating cofilin1 and cofilin2, destrin, and transgelin2 showed the highest degree of differential regulation. CONCLUSIONS: High levels of FSS cause a strong arteriogenic response, reinstate cellular proliferation, stimulate cytoskeletal rearrangement, and normalize maximal conductance. FSS is the initiating molding force in arteriogenesis. The role of fluid shear stress on the development of a collateral circulation was studied by abruptly increasing collateral blood flow by a distal femoral artery-to-vein anastomosis. This increased number and size of collateral vessels to a hitherto unknown degree. Fluid shear stress is the primary and strongest arteriogenic stimulus.

Actin Depolymerizing Factors↗
PubMed2004

Collateral artery growth (arteriogenesis) after experimental arterial occlusion is impaired in mice lacking CC-chemokine receptor-2.

Arteriogenesis has been associated with the presence of monocytes/macrophages within the collateral vessel wall. Induced macrophage migration in vivo is driven by the binding of monocyte chemoattractant protein-1 (MCP-1, or CCL2 in the new nomenclature) to the CCR2-chemokine receptor on macrophages. To determine whether the CCL2-CCR2 signaling pathway is involved in the accumulation of macrophages in growing collateral vessels, we used mice that are deficient in CCR2 in a model of experimental arterial occlusion and collateral vessel growth. In an in vitro CCL2-driven chemotaxis assay, mononuclear cells isolated from wild-type BALB/c mice exhibited CCL2 concentration-dependent migration, whereas this migration was abolished in cells from CCR2(-/-) mice on a BALB/c genetic background. In vivo, blood flow recovery as measured by laser Doppler (LDI) and MRI (MRI) was impaired in CCR2(-/-) mice on either the BALB/c or C57BL/6 genetic backgrounds. Three weeks after femoral artery ligation, LDI perfusion ratio of operated versus nonoperated distal hindlimb in BALB/c wild-type mice increased to 0.45+/-0.06 and in CCR2(-/-) animals only to 0.21+/-0.03 (P<0.01). In C57BL/6 mice, ratio increased to 0.96+/-0.09 and 0.85+/-0.08 (P<0.05), respectively. MRI at 3 weeks (0.76+/-0.06 versus 0.62+/-0.01; P<0.05) and hemoglobin oxygen saturation measurements confirmed these findings. Active foot movement score significantly decreased and gastrocnemius muscle atrophy was significantly greater in CCR2(-/-) mice. Morphometric analysis showed a lesser increase in collateral vessel diameters in CCR2(-/-) mice. Importantly, the number of invaded monocytes/macrophages in the perivascular space of collateral arteries of CCR2(-/-) animals was dramatically reduced in comparison to wild-type mice. In conclusion, our results demonstrate that the CCR2 signaling pathway is essential for efficient collateral artery growth.

Animals↗
PubMed2004

Simultaneous activation of several second messengers in hypoxia-induced hyperpermeability of brain derived endothelial cells.

In vivo, ischemia is known to damage the blood-brain barrier (BBB) leading to the development of vasogenic brain edema. Hypoxia-induced vascular endothelial growth factor (VEGF) has been shown to be a key regulator of these permeability changes. However, the signaling pathways that underlie VEGF-induced hyperpermeability are incompletely understood. In this study, we demonstrate that hypoxia- and VEGF-induced permeability changes depend on activation of phospholipase Cgamma (PLCgamma), phosphatidylinositol 3-kinase/Akt (PI3-K/Akt), and protein kinase G (PKG). Inhibition of mitogen-activated protein kinases (MAPK) and of the protein kinase C (PKC) did not affect permeability at all. Paralleling hypoxia- and VEGF-induced permeability changes, localization of the tight junction proteins occludin, zonula occludens-1 (ZO-1), and ZO-2 along the cell membrane changed from a continuous to a more discontinuous expression pattern during hypoxia. In particular, localization of ZO-1 and ZO-2 expression moved from the cell membrane to the cytoplasm and nucleus whereas occludin expression remained at the cell membrane. Inhibition of PLCgamma, PI3-kinase, and PKG abolished these hypoxia-induced changes. These findings demonstrate that hypoxia and VEGF induce permeability through rearrangement of endothelial junctional proteins which involves activation of the PLCgamma and PI3-K/AKT pathway leading to the activation of PKG.

Animals↗