Effects of sarpogrelate hydrochloride on adenosine diphosphate- or collagen-induced platelet responses in arteriosclerosis obliterans

Serotonin 2A (5-HT2A) receptor affects cell-matrix adhesion and the formation and maintenance of stress fibers in HEK293 cells

5-HT_2A, a G-protein coupled receptor, is widely expressed in the human body, including in the gastrointestinal tract, platelets and the nervous system. It mediates various functions, for e.g. learning, memory, mood regulation, platelet aggregation and vasoconstriction, but its involvement in cell-adhesion remains largely unknown. Here we report a novel role for 5-HT_2A in cell–matrix adhesion.

In HEK293 cells, which are loosely adherent, expression and stimulation of human or rat 5-HT_2A receptor by agonists such as serotonin or 2,5-dimethoxy-4-iodoamphetamine (DOI) led to a significant increase in adhesion, while inhibition of 5-HT_2A by antipsychotics, such as risperidone, olanzapine or chlorpromazine prevented it. 5-HT_2A activation gave rise to stress fibers in these cells and was also required for their maintenance. Mechanistically, the 5-HT_2A-mediated adhesion was mediated by downstream PKC and Rho signaling. Since 5-HT_2A is associated with many disorders such as dementia, depression and schizophrenia, its role in cell–matrix adhesion could have implications for neural circuits.

Serotonin signals through a gut-liver axis to regulate hepatic steatosis

Nonalcoholic fatty liver disease (NAFLD) is increasing in worldwide prevalence, closely tracking the obesity epidemic, but specific pharmaceutical treatments for NAFLD are lacking. Defining the key molecular pathways underlying the pathogenesis of NAFLD is essential for developing new drugs. Here we demonstrate that inhibition of gut-derived serotonin synthesis ameliorates hepatic steatosis through a reduction in liver serotonin receptor 2A (HTR2A) signaling. Local serotonin concentrations in the portal blood, which can directly travel to and affect the liver, are selectively increased by high-fat diet (HFD) feeding in mice. Both gut-specific Tph1 knockout mice and liver-specific Htr2a knockout mice are resistant to HFD-induced hepatic steatosis, without affecting systemic energy homeostasis. Moreover, selective HTR2A antagonist treatment prevents HFD-induced hepatic steatosis. Thus, the gut TPH1-liver HTR2A axis shows promise as a drug target to ameliorate NAFLD with minimal systemic metabolic effects.

No effective pharmacological treatments exist for nonalcoholic fatty liver disease (NAFLD). Here, the authors show that serotonin concentration in the portal blood is increased in nine human subjects and in mice fed a high-fat diet, and that local serotonin signaling ablation, either genetically or with an antagonist, prevents hepatic steatosis in mice.

Effect of sarpogrelate hydrochloride, a 5-hydroxytryptamine2 receptor antagonist, on allograft arteriosclerosis after aortic transplantation in rats

BACKGROUND

Sarpogrelate hydrochloride, a 5-hydroxytryptamine2 receptor antagonist, is known to prevent serotonin-induced neointimal hyperplasia. We examined the effect of this agent on allograft arteriosclerosis in a rat model of aortic transplantation.

METHODS

Rats were given an aortic isograft or allograft and oral administration of either saline vehicle alone or 20mg/kg daily of sarpogrelate for 8 weeks. The grafts were then harvested, and the lumen diameter and the thickness of the intima and media were measured. Comparisons were made between measurement results in isografts and allografts from rats treated and not treated with sarpogrelate. Immunohistochemistry assessments were used to detect expression of serotonin in graft specimens.

RESULTS

For both allografts and isografts, significantly less intimal thickening was observed in specimens from rats given sarpogrelate compared with rats given saline. Sarpogrelate had no effect on medial thickening in either graft type. Serotonin was detected in allografts from rats given saline alone but not in allografts from rats given sarpogrelate or in isografts.

CONCLUSIONS

Sarpogrelate hydrochloride may mitigate arteriosclerosis in allografts. Platelet aggregation and serotonin may be correlated with intimal thickening associated with chronic rejection.

Possible roles of 5-HT in vein graft failure due to intimal hyperplasia 5-HT, nitric oxide and vein graft

For vascular occlusive disease, an autologous vein graft is the most suitable conduit for arterial reconstruction. Intimal hyperplasia, resulting from the migration and proliferation of vascular smooth muscle cells, is a major obstacle to patency after vein grafting. The degree to which the function of nitric oxide (NO) in the vein graft is preserved has been reported to be associated with the magnitude of intimal hyperplasia. Serotonin (5-HT) is released from platelets in the vascular system and plays physiological roles in controlling the vascular tone. The subtype receptors contributing to the 5-HT-induced mechanical responses vary by vessel type (artery and vein) and among species (dogs, rabbits, rats, and so on). Recent studies have demonstrated that 5-HT induces vasoconstriction through the activation of 5-HT2A receptors in smooth muscle cells or vasodilatation through the activation of endothelial 5-HT1B receptors in arteries from various animals. However, the effects of 5-HT have not been clarified in grafted veins. We herein demonstrate the responses to 5-HT in un-operated veins and then autogenous vein grafts. Next, we describe the effects of chronic in vivo administration of Rho-kinase inhibitors and 5-HT2A receptor antagonists, both of which reduce the 5-HT-induced contraction and intimal hyperplasia in vein grafts. Further studies targeting 5-HT are required to evaluate its possible benefits for autologous vein grafts with respect to vasospasm, function, and patency.

Eugenosedin-A prevents hyperglycaemia, hyperlipidaemia and lipid peroxidation in C57BL/6J mice fed a high-fat diet

Objectives

Eugenosedin-A is a serotonin (5-hydroxytryptamine; 5-HT) 5-HT1b/2a and α1/α2/β1-adrenoceptor blocker with anti-oxidative, anti-inflammatory and free-radical scavenging activities. Previous reports demonstrated that 5-HT2a blockers could diminish hyperlipidaemia. This study therefore aimed to investigate the possible uses and mechanisms of eugenosedin-A and other agents in treating hyperlipidaemia.

Methods

C57BL/6J mice were randomly divided into seven groups, fed a regular diet or a high-fat diet alone or supplemented with one of five agents: eugenosedin-A, ketanserin, prazosin, propranolol or atorvastatin (5 mg/kg p.o.) for 8 weeks.

Key findings

Compared with the regular diet, the mice fed the high-fat diet had significantly higher body weight and glucose, insulin and lipid levels. Brain malondialdehyde concentration was increased and liver glutathione peroxidase activity decreased. Addition of eugenosedin-A to the high-fat diet resulted in less weight gain and reduced hyperglycaemia, hyperinsulinaemia and hyperlipidaemia. Lipid and glucose homeostasis were related to decreased hepatic lipogenesis mRNAs and proteins (sterol regulatory element binding protein 1a, fatty acid synthase, sterol-CoA desaturase) and restored adipose peroxisome proliferator-activated receptor γ expression. Eugenosedin-A also enhanced low-density lipoprotein receptor mRNA expression.

Conclusions

Eugenosedin-A may improve plasma lipid metabolism by increasing low-density lipoprotein receptor and peroxisome proliferator-activated receptor γ expression and diminishing sterol regulatory element binding protein 1a, fatty acid synthase and sterol-CoA desaturase. Reduction of plasma glucose and lipid levels may, in turn, reduce insulin concentration, which would explain the marked improvement in obesity-related hyperglycaemia and hyperlipidaemia. Furthermore, eugenosedin-A affected malondialdehyde concentration and glutathione peroxidase activity, suggesting it may have anti-peroxidation effects in mice fed a high-fat diet.

Chronic treatment of hydroxytryptamine type 2a receptor antagonist sarpogrelate hydrochloride modulates the vasoreactivity of serotonin in experimental rabbit vein grafts

OBJECTIVE

It has been suggested that 5-hydroxytryptamine (5-HT) plays a role in the pathogenesis of vein graft spasms. It is suggested that smooth muscle 5-HT(2A) and 5-HT(1B) receptors contribute to 5-HT-induced contraction, while endothelial 5-HT(1B) receptors contribute to the 5-HT-induced endothelium-mediated relaxation. We recently found that chronic administration of the selective 5-HT(2A) receptor antagonist sarpogrelate hydrochloride (SH) enhances the function of endothelium-derived nitric oxide (NO) in rabbit vein grafts. However, it is unknown if such treatment modulates 5-HT-induced vasospasm in vein grafts, and if so, what the underlying mechanisms are.

METHODS

Male rabbits were divided into two groups: a control group and an SH-treated group. The jugular vein was interposed in the carotid artery in reversed fashion. Isometric tension was examined using vein grafts after 4 weeks. 5-HT (10(-8) -10(-6) M)-induced contraction was obtained in each group in the absence or presence of the NO synthase inhibitor l-N(G)-nitroarginine (L-NNA). The expression of 5-HT(2A) and 5-HT(1B) receptors was examined immunohistochemically.

RESULTS

The 5-HT induced a concentration-dependent contractions in both groups. L-NNA did not significantly modify the 5-HT-induced contraction in the control group but enhanced it in the SH group. The 5-HT(1B) receptor antagonist GR55562 inhibited the 5-HT-induced contraction in the control group, while it increased the sensitivity of contraction to 5-HT in the SH-treated group in the absence (but not in the presence) of L-NNA. Positive immunoreactivities against 5-HT(1B) and 5-HT(2A) receptors were identified in endothelial and medial regions of vein grafts in both groups, and the expression of 5-HT(2A) receptors (but not 5-HT(1B) receptors) was significantly less in the SH-treated group than in the control group.

CONCLUSION

Chronically administered SH to rabbits upregulates the autoinhibitory mechanism by 5-HT through a release of NO from endothelium via an activation of endothelial 5-HT(1B) receptors, thus attenuating its own contraction in vein grafts. Furthermore, such SH treatment downregulates the expression of smooth muscle 5-HT(2A) receptors, thus further attenuating the 5-HT-induced contraction. These novel findings further support the clinical usefulness of SH in vein graft spasm after bypass grafting.

Sarpogrelate hydrochloride reduced intimal hyperplasia in experimental rabbit vein graft

OBJECTIVES

The selective 5-HT(2A) receptor antagonist sarpogrelate has been clinically used for treatment in atherosclerotic diseases. However, it remains unknown whether administration of sarpogrelate inhibits intimal hyperplasia seen in autologous vein grafts. Therefore, we sought to clarify this question using an experimental rabbit vein graft model.

METHODS

Male rabbits were divided into two groups: a control group and a sarpogrelate-treated group. The jugular vein was interposed in the carotid artery in reversed fashion for 4 weeks and intimal hyperplasia of the grafted vein was measured (n = 8, in each group). Acetylcholine (ACh)-induced endothelium-dependent relaxation was tested by precontraction with prostaglandin F(2alpha) (PGF(2alpha), 5 muM) (n = 5, in each). endothelial nitric oxide synthase (eNOS) protein expression and superoxide production of these veins were also assessed.

RESULTS

The suppression of intimal hyperplasia was significantly greater in the sarpogrelate-treated group than in the control group. ACh induced an endothelium-dependent relaxation in the sarpogrelate-treated group (but not in the control group). In endothelium-intact strips from the sarpogrelate-treated group, the nitric oxide (NO) synthase inhibitor nitroarginine enhanced the PGF(2alpha)-induced contraction and blocked the ACh-induced relaxation. Immunoreactive eNOS protein expression was similar between the two groups but superoxide production (estimated from ethidium fluorescence) in endothelial cells was significantly smaller in the sarpogrelate-treated group.

CONCLUSION

The present results indicate that in vivo blockade of 5-HT(2A) receptors leads to an inhibition of intimal hyperplasia in rabbit vein graft. It is suggested that an increased function of endothelium-derived NO through a reduction in endothelial superoxide production may be a possible underlying mechanism for this. These novel findings support the clinical usefulness of sarpogrelate for preventing intimal hyperplasia in vein graft after bypass grafting.

Comparison of sarpogrelate and ticlopidine in bare metal coronary stent implantation

BACKGROUND

The efficacy and safety of sarpogrelate, a selective 5-hydroxytryptamine receptor subtype 2A antagonist, have not yet been established in bare metal coronary stenting. Accordingly, we sought to clarify whether treatment with sarpogrelate is clinically useful in bare metal coronary stenting.

METHODS

A total of 450 patients who underwent successfully planned or unplanned bare metal coronary stenting were randomly divided into the following 2 groups: the sarpogrelate (300 mg/day) plus aspirin (100 mg/day) group (group S, n=225) and the ticlopidine (200 mg/day) plus aspirin (100 mg/day) group (group T, n=225). Either sarpogrelate or ticlopidine was administered for at least 4 weeks after the procedure. Follow-up coronary arteriography was performed at 6 months after the procedure. The primary endpoints were the incidence of adverse drug reactions requiring a withdrawal of treatment and the rate of binary restenosis. The secondary endpoint was the incidence of stent thrombosis.

RESULTS

The incidence of adverse drug reactions requiring a withdrawal of treatment was significantly lower in group S than in group T (0.44% vs 8%, p=0.002). The rate of binary restenosis did not differ significantly between groups S and T (16.9% vs 18.2%). In addition, the incidence of subacute stent thrombosis did not differ between groups S and T (0.44% vs 0.44%).

CONCLUSIONS

The incidence of adverse drug reactions requiring a withdrawal of treatment was significantly lower with sarpogrelate use than with ticlopidine use. The rate of binary restenosis and the incidence of subacute stent thrombosis did not differ between both drug groups.

Sarpogrelate Hydrochloride, a Selective 5-HT2A Antagonist, Improves Vascular Function in Patients With Peripheral Arterial Disease

Peripheral arterial disease (PAD) is 1 of the major manifestations of atherosclerosis. PAD is associated with endothelial dysfunction. Sarpogrelate hydrochloride, a selective 5-HT2A antagonist, has been widely used as an anti-platelet agent for the treatment of PAD. There is no information on whether endothelial function is improved after initiation of sarpogrelate treatment in patients with PAD. The purpose of this study was to evaluate the effects of sarpogrelate on endothelial function in patients with PAD. We divided PAD patients into 2 groups: those treated with sarpogrelate at a dose of 100 mg 3 times per day orally for 12 weeks (sarpogrelate group, n = 10), and those who remained on conventional therapy (control group, n = 11). Forearm blood flow (FBF) and leg blood flow (LBF) responses to reactive hyperemia (RH) and sublingual administration of nitroglycerin (NTG) were measured using strain-gauge plethysmography. After 12 weeks of sarpogrelate administration, FBF and LBF responses during RH showed significant increases from 13.2 +/- 1.7 to 18.1 +/- 2.2 mL/min per 100 mL tissue (P < 0.01) and from 8.2 +/- 0.9 to 14.2 +/- 2.1 mL/min per 100 mL tissue (P < 0.05), respectively. Sarpogrelate-induced augmentation of FBF and LBF responses to RH was maintained at 24 weeks. No change was observed in the control group at each follow-up time point. The changes in FBF and LBF after sublingual NTG were similar during follow-up periods in the 2 groups. These findings suggest that long-term oral administration of sarpogrelate improves vascular function in patients with PAD.

Induction of Indefinite Survival of Fully Mismatched Cardiac Allografts and Generation of Regulatory Cells by Sarpogrelate Hydrochloride

BACKGROUND

At initiation of the immunologic response, platelets rapidly release chemical mediators such as serotonin (5-hydroxytryptamine, [5-HT]) and cytokines. Sarpogrelate hydrochloride (SH), a selective 5-HT2-receptor antagonist, is used to treat patients with peripheral arterial disease. We investigated the effect of SH on the alloimmune response in a murine cardiac transplantation model.

METHODS

CBA mice underwent transplantation of a C57BL/10 heart and received a short course of SH treatment. Survival of the allograft was recorded. An adoptive transfer study was performed to determine whether regulatory cells were generated. Immunohistochemistry studies of intercellular adhesion molecule 1 (ICAM-1), histological, cell-proliferation, and cytokine assessments were performed.

RESULTS

Untreated CBA mice rejected C57BL/10 cardiac grafts acutely (median survival time [MST], 8 days). In mice given 10 mg/kg of SH, all allografts survived indefinitely (MST, >100 days); these mice also had significantly prolonged survival of donor-specific skin grafts but acute rejection of third-party skin grafts. Secondary CBA recipients given not only whole but also CD4 splenocytes from primary SH-treated CBA recipients with C57BL/10 cardiac allograft had indefinite survival of C57BL/10 hearts (MST, >100 days). SH inhibited upregulation of ICAM-1 on endothelial cells in the allografts. Graft acceptance and hyporesponsiveness were confirmed by the histological and cell-proliferation studies, respectively. Production of interleukin-4 and interleukin-10 from splenocytes of SH-treated transplant recipients increased compared to that from splenocytes of untreated recipients.

CONCLUSION

SH induced indefinite survival of fully allogeneic cardiac allografts, generated CD4 regulatory cells, inhibited ICAM-1 expression in the allografts, and upregulated IL-4 and IL-10 production.

Therapeutic Potentials of Sarpogrelate in Cardiovascular Disease*

In view of the pivotal role of serotonin (5-HT) in a wide variety of cardiovascular disorders, extensive effort has been made to develop different types of 5-HT receptor antagonists for therapeutic use. On the basis of experimental studies, this article is focused on the potentials of sarpogrelate, a specific 5-HT2A receptor antagonist as an antiplatelet, antithrombotic, antiatherosclerotic and antianginal agent. The major effects of sarpogrelate are due to the inhibition of 5-HT-induced platelet aggregation and smooth muscle cell proliferation. This agent was found to attenuate the 5-HT-mediated increase in intracellular Ca2+ and ischemia-reperfusion injury in the heart. Sarpogrelate has been found to have beneficial effects in peripheral vascular disease, restenosis after coronary stenting, pulmonary hypertension, acute and chronic myocardial infarction.

The 5-hydroxytryptamine2A receptor antagonist sarpogrelate hydrochloride inhibits acute platelet aggregation in injured endothelium

In this study, the effect of sarpogrelate hydrochloride, a 5-hydroxytryptamine2A receptor antagonist, on platelet aggregation at the site of injured carotid artery endothelium was examined. The rat common carotid artery was clamped for 30 min to induce endothelial injury. Sarpogrelate hydrochloride was administered before and after the injury, and the effects were compared with those in rats receiving sham operation only and those receiving clipping injury but no sarpogrelate hydrochloride. The animals were killed 24 h after the procedure. The common carotid artery was examined by scanning electron microscopy and stained immunochemically for factor VIII. Sarpogrelate hydrochloride treatment was associated with reduced aggregation of platelets on electron microscopy and lower expression of factor VIII at the injured intima. Sarpogrelate hydrochloride has an inhibitory effect on platelet aggregation at the intima in the acute stage after injury, suggesting that this drug may be used to prevent early ischaemic complications after surgical or endovascular arterial intervention.

Inhibitory effects of edaravone on the production of tumor necrosis factor-α in the isolated heart undergoing ischemia and reperfusion

We evaluated the effects of edaravone, a hydroxyl radical scavenging agent, on the production of tumor necrosis factor-alpha (TNF-alpha) in myocardium, and the release of TNF-alpha and P-selectin from myocardium after ischemia-reperfusion injury in isolated Langendorff-perfused rat hearts. Cardiodynamic function at stable points during perfusion and 5, 15, 30, and 60 min after the initiation of reperfusion was evaluated by left ventricular developed pressure, rate of increase in left ventricular pressure and rate of decrease in ventricular pressure, coronary flow, and heart rate. At 60 min after the initiation of reperfusion, myocardial infarct size was estimated microscopically using triphenyltetrazolium chloride staining, and expression of TNF-alpha in myocardium was detected by Western blot and immunohistochemistry. At the same time points as the measurement of cardiodynamic function, TNF-alpha and the soluble form of P-selectin in coronary effluent were measured by enzyme immunoassay. At all time points during reperfusion, edaravone markedly improved cardiodynamic function and reduced myocardial infarct size in comparison to the control. In myocardium in the control, TNF-alpha was detected in the endothelial cells and other cells bearing some resemblance to interstitial cells and monocyte cells. Edaravone suppressed this cytokine expression in the corresponding sites. P-selectin as well as TNF-alpha was found in the coronary effluent of the control, and edaravone significantly decreased soluble P-selectin levels in comparison to the control (P < 0.01). Edaravone might have protective effects on cardiac function through reduction of infarct size via decrease of production of TNF-alpha in myocardium induced by ischemia-reperfusion injury and through reduction of the release of adhesion molecules such as P-selectin from vascular endothelial cells.

5-HT2A receptor antagonist increases circulating adiponectin in patients with type 2 diabetes

We compared the levels of plasma adiponectin, platelet activation markers (P-selectin, CD63, PAC-1, annexin V, and platelet-derived microparticles), and endothelial injury markers (soluble E-selectin and soluble vascular cell adhesion molecule-1) in 53 patients with type 2 diabetes mellitus to investigate potential contributions to diabetic vascular complications. In addition, we administered serotonin antagonist (sarpogrelate hydrochloride) to type 2 diabetes patients who had increased soluble E-selectin levels. The concentrations of platelet activation markers and endothelial injury markers in diabetic patients were significantly higher than those in normal subjects. However, levels of adiponectin were lower in type 2 diabetes patients than in control subjects. A total of 32 patients had high-soluble E-selectin levels (soluble E-selectin >or= 62 ng/ml); a subset of patients that also had significant elevation of platelet activation and endothelial injury markers compared with patients without high soluble E-selectin. In addition, both platelet-P-selectin and platelet-derived microparticle levels negatively correlated with the adiponectin level. Patients with high soluble E-selectin exhibited significant improvement of all markers after sarpogrelate hydrochloride treatment. These findings suggest that there is a link between vascular change in type 2 diabetes and activated platelets, endothelial dysfunction, and an adiponectin abnormality.

Serotonin acts as an up-regulator of acyl-coenzyme A:cholesterol acyltransferase-1 in human monocyte-macrophages

Acyl-coenzyme A:cholesterol acyltransferase-1 (ACAT-1) converts intracellular free cholesterol into cholesterol ester for storage in lipid droplets and plays an important role in the formation of macrophage-derived foam cells in atherosclerotic lesions. Serotonin (5-HT), a potent vasoconstrictor that is released from activated platelets, increases uptake of oxidized low-density lipoprotein (LDL) by macrophages, leading to foam cell formation, and contributes to the development of atherosclerotic plaque. However, it is not yet known whether 5-HT affects ACAT-1 expression in human monocyte-macrophages as the molecular mechanism of enhanced foam cell formation by 5-HT remains unclear. We examined the effects of 5-HT on ACAT-1 expression during differentiation of cultured human monocytes into macrophages. Expression of ACAT-1 protein but not 5-HT2A receptor increased in a time-dependent manner. 5-HT increased ACAT activity in a concentration-dependent manner after 7 days in primary monocyte culture. Immunoblotting analysis showed that 5-HT at 10 microM increased ACAT-1 protein expression level by two-fold, and this effect was abolished completely by a 5-HT2A receptor antagonist (sarpogrelate), its major metabolite (M-1), a G protein inactivator (GDP-beta-S), a protein kinase C (PKC) inhibitor (rottlerin), a Src family inhibitor (PP2), or a mitogen-activated protein kinase (MAPK) kinase inhibitor (PD98059). Northern blotting analysis indicated that among the four ACAT-1 mRNA transcripts (2.8-, 3.6-, 4.3-, and 7.0-kb), the levels of the 2.8- and 3.6-kb transcripts were selectively up-regulated by approximately 1.7-fold by 5-HT (10 microM). The results of the present study suggested that 5-HT may play a crucial role in macrophage-derived foam cell formation by up-regulating ACAT-1 expression via the 5-HT2A receptor/G protein/c-Src/PKC/MAPK pathway, contributing to the progression of atherosclerotic plaque.

Sarpogrelate: cardiovascular and renal clinical potential

Sarpogrelate is a selective 5-hydroxytryptamine receptor subtype 2A (5-HT2A) antagonist. It is metabolised to racemic M-1 and both enantiomers of M-1 are also antagonists of 5-HT2A receptors. Sarpogrelate inhibits responses to 5-HT mediated by 5-HT2A receptors such as platelet aggregation, vasoconstriction and vascular smooth muscle proliferation. There is no information available on the pharmacokinetics of sarpogrelate. Sarpogrelate is efficacious in animal models of thrombosis, coronary artery spasm, atherosclerosis, restenosis, peripheral vascular disease, pulmonary hypertension, ischaemic heart disease, myocardial infarction, diabetes and kidney disease. Small clinical trials indicate that sarpogrelate may be beneficial in the treatment of coronary artery disease, angina, restenosis, heart valve prostheses surgery, diabetes mellitus, Raynaud's phenomenon, systemic sclerosis and Buerger's disease. Larger, randomised, double-blind, placebo-controlled clinical trials of sarpogrelate in intermittent claudication, coronary artery disease, restenosis and diabetes should be considered.

Relationship between cerebral injury and inflammatory responses in patients undergoing cardiac surgery with cardiopulmonary bypass

This study was performed to evaluate whether cytokines, adhesion molecules, ghrelin and S-100B are useful markers in predicting the cerebral infarction after cardiac surgery with cardioplumomary bypass (CPB). The patients (n=20) were classified into two groups; group A (n=4) showed postoperative organized cerebral damage, while group B (n=16) consisted of patients without occurrence of postoperative strokes. Before CPB, serum levels of S-100B in both groups A and B were low (<0.5 ng/mL), while ghrelin concentrations in group A (all patients had history of strokes) were much higher than those in group B. After CPB, when serum levels of S-100B in group A at 24h were higher than those in group B, ghrelin in group A at same time point showed high levels in comparison to group B. At 12 and 24h after CPB, levels of tumor necrosis factor (TNF)-alpha, interleukin-10 and soluble TNF-receptor I in group A were significantly higher than those in group B. In conclusion, it is considered that ghrelin as well as S-100B can be a useful marker for the prediction of stoke after CPB. Increase of TNF-alpha, interleukin-10 and soluble TNF-receptor I after CPB may be involved in the pathogenesis of stroke after CPB.

The ratio of plasma to whole-blood serotonin may be a novel marker of atherosclerotic cardiovascular disease

Because atherosclerotic vascular lesions stimulate platelets, the platelets release serotonin (5-hydroxytryptamine, aka 5-HT). We therefore measured 5-HT concentrations not only in platelet-poor plasma but also in whole blood as a means of assessing vascular lesions. The plasma concentration of 5-HT tended to increase with age, whereas that in whole blood decreases. Therefore the ratio of the plasma to the whole-blood concentration of 5-HT (P/WB) increases with age. This may be a result of the activation of platelets in older subjects with atherosclerotic vascular damage. Patients who underwent coronary angiography (CAG) were classified into 4 groups according to diagnosis: effort-induced angina pectoris (eAP), old myocardial infarction (OMI), vasospastic angina pectoris (VSAP), and unstable angina (uAP). The mean plasma 5-HT concentration was significantly (P <.01) greater in patients with eAP, uAP, OMI, and VSAP than in healthy controls, whereas the concentration in whole blood was lower in patients with eAP than in healthy controls. When the P/WB ratios were calculated, the mean levels in all disease groups were significantly higher than that in the healthy controls. These findings suggested that 5-HT is released into the plasma from the platelets and that the concentration in the platelets decreases in patients with atherosclerosis.

Evaluation of anti-platelet aggregatory effects of aspirin, cilostazol and ramatroban on platelet-rich plasma and whole blood

To compare property in anti-platelet effects of aspirin (a cyclooxygenase inhibitor), cilostazol (a phosphodiesterase III inhibitor) and ramatroban (a specific thromboxane A2 receptor antagonist), we measured human platelet-rich plasma (PRP) aggregation induced by adenosine diphosphate (ADP), collagen and arachidonic acid, and whole blood (WB) aggregation induced by ADP. The release of P-selectin, transforming growth factor-beta 1, and the formation of thromboxane A2 in response to agonists were also investigated. Inhibitory effects of 100 micromol/l aspirin, 10 micromol/l cilostazol and 1 micromol/l ramatroban on 5 micromol/l ADP-induced PRP aggregation were similar. However, aspirin strongly inhibited thromboxane A2 formation in response to 5 micromol/l ADP compared with other drugs. Inhibitory effects of 10 micromol/l cilostazol on PRP aggregation and the release of molecules were quite similar in responsiveness induced by the three agonists. Aspirin and cilostazol inhibited platelet aggregation in a concentration-dependent, non-linear fashion, while ramatroban inhibited linearly with increasing concentration. Anti-platelet effects of drugs having different pharmacological mechanisms were demonstrated clearly by measuring PRP aggregation induced by the three agonists, and by measuring WB aggregation that most probably reflects not only platelet-platelet interactions, but also platelet-leukocyte interactions, as well as the release of intraplatelet molecules.