Yasuhiko Mitsuke

Different effects of calcium channel blockers on matrix metalloproteinase-2 expression in cultured rat cardiac fibroblasts.

The cardiac effects of calcium channel blockers (CCBs) related to cardiac remodeling are inconsistent. Matrix metalloproteinases (MMPs) contribute to tissue remodeling. Cardiac fibroblasts play an important role in the regulation of collagen degradation by MMPs. Using gelatin zymography, Western blotting, Griess reagent, and a calcium kit-fluo 3, we investigated the effects of nifedipine, verapamil, diltiazem, and amlodipine on MMP-2 expression and further elucidate the mechanisms in cultured rat cardiac fibroblasts. Nifedipine increased and amlodipine decreased the expression of MMP-2; however, neither verapamil nor diltiazem altered MMP-2 expression. Nifedipine also increased nitrite production, and this increase was blunted by a nitric oxide (NO) synthases inhibitor (L-NAME). Nifedipine-induced MMP-2 expression was also blunted by L-NAME. An NO donor (sodium nitroprusside) induced MMP-2 expression. Data indicated that nifedipine might increase MMP-2 expression through a possible NO-dependent pathway. Amlodipine had no influence on nitrite production. The amlodipine-induced decrease of MMP-2 expression was abolished by two protein tyrosine kinase inhibitors, genistein and herbimycin A, indicating that amlodipine might decrease MMP-2 expression through a possible protein tyrosine kinase pathway. None of the four CCBs could alter the fluoscence intensity of fluo 3, indicating that the effects of CCBs on MMP-2 expression were independent of the variation in intracellular Ca2+ concentration. Our findings revealed that different CCBs exerted different effects on MMP-2 expression in cardiac fibroblasts.

Nitric Oxide Synthase Activity in Peripheral Polymorphonuclear Leukocytes in Patients With Chronic Congestive Heart Failure

Increased activity of inducible nitric oxide synthase (NOS) has been found in cardiac tissue and in skeletal muscle from patients with chronic congestive heart failure (CHF). There have been few reports investigating NOS activity in other organs or in peripheral blood cells from patients with chronic CHF. To examine whether NOS activities in peripheral polymorphonuclear leukocytes (PML) are increased in patients with chronic CHF and to determine whether a correlation exists between disease severity and NOS activity in PML of patients with chronic CHF, we assessed the levels of NOS activity in PML by measuring the capacity of isolated PML to convert 3H-L-arginine to 3H-L-citrullin in 70 Japanese patients with chronic CHF and in 24 age-matched healthy volunteers. The levels of NOS activity in PML were significantly greater in patients with chronic CHF than in healthy volunteers (18.0 +/- 0.6% vs 11.5 +/- 0.3%, p <0.01). NOS activity in PML was increased with the severity of New York Heart Association functional class. Among the various neurohumonal factors, the plasma levels of interleukin-6, atrial natriuretic peptide, and norepinephrine showed independent and significant positive relations with levels of NOS activity in PML. Thus, we demonstrated that NOS activity in PML was elevated in patients with chronic CHF in relation to the severity of heart failure, circulating proinflammatory cytokines, and neurohormonal factors.

Effects of magnesium on the production of extracellular matrix metalloproteinases in cultured rat vascular smooth muscle cells

The precise correlation between magnesium and cardiovascular disease remains to be established. Matrix metalloproteinases (MMPs) are expressed in coronary arterial atherosclerotic lesions. MMP production in vascular smooth muscle cells (VSMCs) is stimulated by growth factors such as platelet-derived growth factor (PDGF). To assess the association between magnesium and MMPs, we examined the effects of different extracellular magnesium concentrations (0-3.0 mmol/l) on MMPs production in cultured rat VSMCs under basal and PDGF-stimulated conditions using gelatin zymography and western blotting. As magnesium is called a natural calcium antagonist, we further compared the effects of magnesium with some calcium antagonists. Magnesium reduced MMP-2 production dose-dependently at basal and PDGF-stimulated conditions in VSMCs. However, neither verapamil nor nifedipine influenced MMP-2 production under any conditions examined. The effect of magnesium on the production of MMP-2 was inhibited by two tyrosine kinase inhibitors-genistein and herbimycin A. The results of this study indicate that extracellularly added magnesium decreased MMPs secretion, which appears to be associated with protein tyrosine kinase.

Acarbose treatments improve arterial stiffness in patients with type 2 diabetes mellitus.

Aims/Introduction:  Although the improvement of postprandial hyperglycemia by an alpha‐glucosidase inhibitor (α‐GI) has been associated with a risk reduction of cardiovascular events, the relationship between postprandial hyperglycemia and arterial stiffness has not been well understood. We therefore examined whether ameliorating the postprandial state by α‐GI leads to an improvement in arterial stiffness.

Predictive Utility of the Changes in Matrix Metalloproteinase‐2 in the Early Phase for Left Ventricular Reverse Remodeling After an Acute Myocardial Infarction

Background The relationship between the serum levels of matrix metalloproteinase (MMP) and tissue inhibitors of MMP (TIMP) and left ventricular (LV) reverse remodeling (LV‐RR) after an acute myocardial infarction (AMI) has not been sufficiently examined. Methods and Results In 25 patients with successful reperfusion after an AMI and 15 normal control subjects, the serum MMP‐2 and TIMP‐2 levels were measured on days 1, 2, 3, and 7 and at 1 and 6 months after the AMI onset. LV‐RR was defined as a >15% decrease in the LV end‐systolic volume index at 6 months after the AMI. The MMP‐2 level on day 1 and TIMP‐2 levels throughout the study period were comparable between the patients with and without LV‐RR. The MMP‐2 on day 7 (P<0.05) and the changes in the MMP‐2 from day 1 to day 7 (∆MMP‐2; P<0.01) were lower in patients with than in those without LV‐RR. The ∆MMP‐2 was strongly correlated with the changes in the LV volume and ejection fraction from 1 month to 6 months after the AMI. The ∆MMP‐2 value of <−158.5 ng/mL predicted LV‐RR with a high accuracy (91.7% sensitivity and 76.9% specificity; area under the curve=0.82). Conclusions Changes in MMP‐2 are associated with LV‐RR after an AMI. The ΔMMP‐2 might be a useful predictor of subsequent LV‐RR.

Beneficial effects of statin treatment on coronary microvascular dysfunction and left ventricular remodeling in patients with acute myocardial infarction

BACKGROUND Statin treatment has been shown to improve coronary endothelial function, irrespective of lipid-lowering effects. This studys aim was to elucidate the effects of statin treatment on coronary microvascular dysfunction and left ventricular remodeling in acute myocardial infarction (AMI) patients. METHODS Thirty-five patients undergoing successful reperfusion following AMI were assigned to a statin-treated (Group S, 16) or a non-statin-treated (Group NS, 19) group, according to fasting serum low-density lipoprotein-cholesterol. (13)N-ammonia positron emission tomography was performed to assess myocardial flow reserve (MFR) in the infarct area. RESULTS Infarct sizes and lipid profiles during the chronic period were similar between the two groups. At 2 weeks after AMI onset, mean MFR in the infarct area was significantly higher in Group S than in Group NS (2.34 ± 0.63 vs. 1.91 ± 0.43, p=0.0214). At 6 months post-AMI, Group S had a smaller left-ventricular end-diastolic volume index (69.4 ± 11.7 mL/m(2) vs. 88.5 ± 32.5 mL/m(2), p=0.0328) and higher left-ventricular ejection fraction (67.7 ± 9.2% vs. 59.2 ± 13.3%, p=0.0394) than Group NS. Serum asymmetric dimethylarginine was significantly increased in Group NS at 1 month post-AMI (0.43 ± 0.12 μmol/L (baseline) vs. 0.52 ± 0.14 μmol/L, p=0.0186), but unchanged in Group S. CONCLUSIONS Statin treatment appears to beneficially attenuate left ventricular remodeling after AMI, which may be associated with restoring coronary endothelial function via endogenous nitric oxide.

Association between matrix metalloproteinase-9 and worsening heart failure events in patients with chronic heart failure: MMP-9 predicts HF events

Matrix metalloproteinase (MMP) is up‐regulated during heart failure (HF) and influences ventricular remodeling. We hypothesized that disparity between MMP‐9 and tissue inhibitors of MMP‐1 (TIMP‐1) results in clinical manifestations and is related to prognostic risk in patients with chronic HF.

Relationship between microcirculatory dysfunction and resolution of ST-segment elevation in the early phase after primary angioplasty in patients with ST-segment elevation myocardial infarction.

BACKGROUNDS AND OBJECTIVES The aim of this study was to evaluate relationships between the degree of resolution of the ST-segment elevation (ST segment resolution; STR) and the extent of microcirculatory dysfunction in infarct-related area (IRA) in patients with ST-segment elevation myocardial infarction (STEMI) using (13)N-ammonia positron emission tomography (N-PET). METHODS The subjects comprised 33 patients with STEMI who underwent successful reperfusion. Serial 12-lead electrocardiography (ECG) was performed at the baseline and at 100 min after reperfusion to calculate STR. The myocardial flow reserve (MFR) was assessed quantitatively using N-PET at 2 weeks after the onset. The summed defect score (SDS) of (99m)Tc-tetrofosmin myocardial perfusion imaging was used as an index of the severity of myocardial infarction. To assess the extent of post-infarct left ventricular remodeling, the changes in the LVEDVI (ΔEDVI) were also calculated. RESULTS A significant correlation of the STR to the MFR in IRA (r = 0.68, p < 0.0001) was observed. A significant correlation was also identified between the SDS and the baseline sum ST-segment elevation (r = 0.65, p < 0.0001), while no correlation was observed between the SDS and the STR. Furthermore, a significant inverse correlation of the STR with the ΔEDVI was also recognized (r = -0.58, p < 0.01). CONCLUSIONS These data indicate that STR after successful reperfusion in STEMI is closely related to the extent of microcirculatory disturbance; in other words, incomplete STR may be a marker of persistent microcirculatory dysfunction after reperfusion therapy.

A precise pharmacodynamic study showing the advantage of a marked reduction in cardiotoxicity in continuous infusion of doxorubicin

We have already shown that the antileukemic activity of daunorubicin that had been reported to be dependent on the area under the concentration – time curve (AUC) was actually peak concentration (Cmax) dependent. The antitumor activity of doxorubicin (DXR) has also been reported to be dependent on AUC, whereas its cumulative cardiotoxicity has been reported to be Cmax dependent. In this study, we evaluated whether the antileukemic and cardiotoxic effects of DXR were AUC or Cmax dependent, and compared their cytotoxic effects, utilizing the computer-controlled in vitro pharmacokinetic simulation system or a conventional culture system for a leukemic cell line and measuring the intracellular ATP amount or the proportion of beating cells for the cardiotoxicity. In leukemic cells, the cytotoxic rate decreased as the simulated infusion time or exposure time increased with the same AUC value in the simulation and conventional culture system (P < 0.05 and <0.01, respectively). The intracellular ATP and proportion of beating cells also increased with prolonged DXR exposure time with the same constant concentration – time product value (P < 0.05 and <0.0001, respectively) in heart cells. These results indicated that both the antileukemic effects and the cardiotoxicity were Cmax dependent. However, a comparison of the two showed that cardiotoxicity was more Cmax dependent than the antileukemic effect. These results suggested that the continuous infusion treatment schedule of DXR may have the clinical advantage of reducing cardiotoxicity more markedly than the antileukemic effect.

Effect of tranilast on extracellular matrix metalloproteinases production and no production in cultured vascular smooth muscle cells

Purpose: Tranilast, an antiallergenic drug, has been reported to reduce restenosis rate after angioplasty, but its mechanism is still unclear. Vascular smooth muscle cells (VSMC) proliferation, excessive matrix metalloproteinases (MMPs) expression and nitric oxide (NO) deficiency are thought to be key events in the development of restenosis after angioplasty. We investigated the effect of tranilast on proliferation, MMPs production, and NO production in cultured VSMC under basal and stimulated conditions. Method: Cell proliferation was evaluated by [3H]thymidine incorporation. MMPs production by VSMC were assessed by gelatin zymography. NO production by VSMC was measured by Griess reaction. Results: Tranilast (30-500/z M) did not change proliferation and MMP-2 production in quiescent VSMC. However, tranilast dose-dependently inhibited PDGFstimulated cell proliferation and PDGF-stimulated MMP-2 production. Tranilast also dose-dependently inhibited ILl/~ stimulated MMP-9 and MMP-2 productions. Moreover, tranilast increased basal and ILl/3-stimulated NO production. Conclusion: Our results suggest that prevention of restenosis after angioplasty by tranilast may be madiated by not only its antiproliferative effect but also inhibition of MMPs production and activation of NO production in VSMC.