Mechanisms of subcellular remodeling in heart failure due to diabetes.

Diabetic cardiomyopathy is not only associated with heart failure but there also occurs a loss of the positive inotropic effect of different agents. It is now becoming clear that cardiac dysfunction in chronic diabetes is intimately involved with Ca(2+)-handling abnormalities, metabolic defects and impaired sensitivity of myofibrils to Ca(2+) in cardiomyocytes. On the other hand, loss of the inotropic effect in diabetic myocardium is elicited by changes in signal transduction mechanisms involving hormone receptors and depressions in phosphorylation of various membrane proteins. Ca(2+)-handling abnormalities in the diabetic heart occur mainly due to defects in sarcolemmal Na(+)-K(+) ATPase, Na(+)-Ca(2+) exchange, Na(+)-H(+) exchange, Ca(2+)-channels and Ca(2+)-pump activities as well as changes in sarcoplasmic reticular Ca(2+)-uptake and Ca(2+)-release processes; these alterations may lead to the occurrence of intracellular Ca(2+) overload. Metabolic defects due to insulin deficiency or ineffectiveness as well as hormone imbalance in diabetes are primarily associated with a shift in substrate utilization and changes in the oxidation of fatty acids in cardiomyocytes. Mitochondria initially seem to play an adaptive role in serving as a Ca(2+) sink, but the excessive utilization of long-chain fatty acids for a prolonged period results in the generation of oxidative stress and impairment of their function in the diabetic heart. In view of the activation of sympathetic nervous system and renin-angiotensin system as well as platelet aggregation, endothelial dysfunction and generation of oxidative stress in diabetes and blockade of their effects have been shown to attenuate subcellular remodeling, metabolic derangements and signal transduction abnormalities in the diabetic heart. On the basis of these observations, it is suggested that oxidative stress and subcellular remodeling due to hormonal imbalance and metabolic defects play a critical role in the genesis of heart failure during the development of diabetic cardiomyopathy.

Effect of rosuvastatin on systemic blood pressure in patients with hypercholesterolemia.

OBJECTIVE: To investigate whether rosuvastatin reduces blood pressure (BP) in patients with hypercholesterolemia. METHODS: The present study investigated the effect of rosuvastatin on lipids and clinical parameters in 25 patients with a mean (± SD) age of 58.4±10.6 years over a three-month period. RESULTS: Rosuvastatin (2.5 mg/day to 5.0 mg/day) reduced systolic BP from 136.3±13.1 mmHg to 130.8±10.7 mmHg (P<0.01), along with a significant reduction in serum low-density lipoprotein cholesterol level (P<0.01). The patients were divided into two groups: 13 responders whose BP decreased by >5 mmHg with rosuvastatin treatment and 12 nonresponders who showed a BP reduction of ≤5 mmHg. Baseline systolic BP was significantly higher in responders than nonresponders (143.6±9.6 mmHg versus 128.4±11.9 mmHg, respectively; P<0.01). Responders also had a lower serum concentration of high-sensitivity C-reactive protein compared with nonresponders (0.11±0.07 mg/dL versus 0.40±0.28 mg/dL; P<0.01). The extent of BP reduction was positively correlated with baseline systolic BP (r=0.585; P=0.0021) but not with the reduction of low-density lipoprotein cholesterol level. Among the patients with baseline systolic BP >130 mmHg, all 11 responders (138.3 mmHg) were nonsmokers, while five of six nonresponders (145.7 mmHg) were smokers. CONCLUSION: Rosuvastatin had an additive antihypertensive effect in patients with poorly controlled hypertension that was independent of its lipid-lowering effect, which may be related to an inflammatory mechanism.

Hemodynamic support by left ventricular assist devices reduces cardiomyocyte DNA content in the failing human heart.

BACKGROUND: Whether adult cardiomyocytes have the capacity to regenerate in response to injury and, if so, to what extent are still issues of intense debate. In human heart failure, cardiomyocytes harbor a polyploid genome. A unique opportunity to study the mechanism of polyploidization is provided through the setting of hemodynamic support by left ventricular assist devices. Hence, the cardiomyocyte DNA content, nuclear morphology, and number of nuclei per cell were assessed before and after left ventricular assist device support. METHODS AND RESULTS: In 23 paired myocardial samples, cardiomyocyte ploidy was investigated by DNA image cytometry, flow cytometry, and in situ hybridization. Nuclear cross-sectional area and perimeters were measured morphometrically, and the binucleated cardiomyocytes were counted. The median of the cardiomyocyte DNA content and the number of polyploid cardiomyocytes both declined significantly from 6.79 c to 4.7 c and 40.2% to 23%, whereas a significant increase in diploid cardiomyocytes from 33.4% to 50.3% and in binucleated cardiomyocytes from 4.5% to 10% after unloading was observed. CONCLUSIONS: The decrease in polyploidy and increase in diploidy after left ventricular assist device suggest a numeric increase in diploid cardiomyocytes (eg, through cell cycle progression with completion of mitosis or by increased stem cells). The cardiac regeneration that follows may serve as a morphological correlate of the recovery observed in some patients after unloading.

TNF-alpha-mediated signal transduction pathway is a major determinant of apoptosis in dilated cardiomyopathy.

Although J2N-k strain of cardiomyopathic hamsters is an excellent model of dilated cardiomyopathy, the presence and mechanisms of apoptosis in the hearts of these genetically modified animals have not been investigated. This study examined the hypothesis that cardiac dysfunction and apoptosis in the cardiomyopathic hamsters were associated with tumour necrosis factor-alpha (TNF-alpha)-mediated signalling pathway involving the activation of some pro-apoptotic proteins and/or deactivation of some antiapoptotic proteins. Echocardiographic assessment of 31-week-old hamsters indicated an increase in the internal dimension of the left ventricle as well as decreases in the ejection fraction, fractional shortening and cardiac output without any evidence of cardiac hypertrophy. Increased level of TNF-alpha and apoptosis in cardiomyopathic hearts were accompanied by increased protein content for protein kinase C (PKC) -alpha and -epsilon isozymes as well as caspases 3 and 9. Phosphorylated protein content for p38 MAPK and NF kappaB was increased whereas that for Erk1/2, BAD and Bcl-2 was decreased in cardiomyopathic hearts. These results support the view that TNF-alpha and PKC isozymes may promote apoptosis due to the activation of p38 MAPK and deactivation of Erk1/2 pathways, and these changes may contribute toward the development of cardiac dysfunction in dilated cardiomyopathy.

Survivin is upregulated during liver regeneration in rats and humans and is associated with hepatocyte proliferation.

BACKGROUND: Survivin regulates cell division and inhibits apoptosis. Liver regeneration is a complex process involving both proliferation and apoptosis. The role of survivin is not well elucidated and no data exist in humans. METHODS: Seventy per cent liver resection was used to investigate liver regeneration in rats. Survivin was identified by means of reverse transcriptase polymerase chain reaction, Western blotting and immunohistochemistry. Proliferation and apoptosis were quantified. Liver biopsies from 33 patients who underwent living donor liver transplantation were used to study survivin immuno-expression, proliferation and apoptosis within the first 17 days after transplantation. Seven healthy donors served as controls. RESULTS: Survivin transcript and protein were significantly upregulated in rat hepatocytes after 24-72 h during regeneration and showed a significant correlation with proliferation but not with apoptosis. In humans, survivin was nearly absent in donor and reperfused liver tissue but increased significantly 5-7 days after transplantation and correlated with proliferation but not with apoptosis. CONCLUSIONS: Survivin is upregulated in human and rodent liver regeneration and correlates with proliferation, suggesting an association of survivin and cell division.

Antiplatelet agents sarpogrelate and cilostazol affect experimentally-induced ventricular arrhythmias and mortality.

Antiplatelet agents, sarpogrelate (SAR), a 5-hydroxy tryptamine 2A receptor antagonist and cilostazol (CIL), a phosphodiesterase-III inhibitor, were observed to be beneficial in attenuating cardiac remodeling and improving cardiac function in congestive heart failure due to myocardial infarction in rats; however, CIL increased ventricular tachycardia and mortality. In order to study the effects of these antiplatelet agents on arrhythmias, Sprague-Dawley rats were pretreated with either SAR or CIL (5 mg/kg/day) for 2 weeks and were then either injected cumulative doses of epinephrine (Epi) or subjected to coronary occlusion. Saline-treated animals served as controls. Electrocardiographic analysis revealed that SAR pretreatment decreased the incidence and severity of ventricular arrhythmias (time of onset of arrhythmias as well as the occurrence of premature ventricular contractions, salvos, tachycardia, and fibrillations), whereas CIL treatment augmented the incidence of cardiac arrhythmias due to both Epi and coronary occlusion. None of the drugs affected the corrected QT interval significantly. Furthermore, the levels of cyclic adenosine monophosphate (cAMP) in left ventricle were markedly higher in CIL-pretreated rats when compared to SAR-pretreated or control rats. It is suggested that an excessive level of cAMP may contribute to increase incidence of ventricular arrhythmias and mortality in animals pretreated with CIL, unlike the SAR-pretreated rats.

Segregation of megakaryocytic or erythroid cells from a megakaryocytic leukemia cell line (JAS-R) by adhesion during culture.

Adhesion is one of the important biologic characteristics of leukemic cells. We previously reported a new megakaryocytic-erythroid cell line, JAS-R. In this study, JAS-R cells were segregated into two types by the differences of attachment to culture dishes. One type (designated as JAS-RAD cells) adhered to the substratum of the culture dishes, while the other (JAS-REN cells) grew as a single-cell suspension. Adhesion of JAS-RAD was inhibited by treatment with RGDS oligopeptide. Flow cytometric analysis revealed that JAS-RAD cells had high expression of CD41a and CD61 versus low CD235a expression, and JAS-REN showed low expression of CD41a, and CD61, and high CD235a. The two phenotypes were reciprocally exchangeable by selecting adherent or suspended cells from each type of culture. Microarray analysis and RT-PCR revealed that JAS-RAD cells expressed four major alpha-granule genes and JAS-REN cells expressed beta-globin. Interestingly, erythropoietin was only secreted by JAS-RAD cells. With regard to transcription factors, it was shown that GFI1, FLI1 and RUNX1 were strongly expressed in JAS-RAD cells while GATA1, FOG1 and NFE2 were equally expressed by both types. These findings indicate that adhesion via integrins is related to the phenotypic shift of JAS-R cells between megakaryocytic and erythroid lineages.

MLF1-interacting protein is mainly localized in nucleolus through N-terminal bipartite nuclear localization signal.

BACKGROUND: The myelodysplasia/myeloid leukemia factor 1-interacting protein (MLF1LP, also called KLIP1 and CENP-50) is reported to localize in both the nucleus and the cytoplasm. To investigate the functions of MLF1IP, its subnuclear localization was studied. MATERIALS AND METHODS: MLF1IP was tagged with green fluorescent protein (EGFP). Fibrillarin was tagged with red fluorescent protein (DsRed). EGFP-tagged MLF1IP deletion vectors were also constructed. Plasmid-constructs were transfected into human cervical adenocarcinoma HeLa cells or monkey kidney fibroblast COS-7 cells, and the localization was studied by either confocal fluorescence microscopy or fluorescence microscopy. RESULTS: Ectopically expressed MLF1IP was localized mainly in the nucleolus. In some cells, small dot-like particles of MLF1IP fluorescence were observed in the nucleoplasm. Co-staining of fibrillarin disclosed that MLF1IP was co-localized with fibrillarin in the nucleolus. Deletion mutants of MLF1IP revealed that the N-terminal bipartite nuclear localization signal (NLS) was responsible for nucleolar targeting. CONCLUSION: MLF1IP was localized mainly in the nucleolus through the N-terminal bipartite NLS and partly in the nucleoplasm featuring small dot-like particles. These findings suggest that MLF1IP may have multi-functions and its different localizations may contribute to carcinogenesis.

Beneficial effect of combination therapy with antihypertensive drugs in patients with hypertension.

BACKGROUND: Cardiac hypertrophy and failure are major complications of hypertension. OBJECTIVES: The beneficial effect of treatment with antihypertensive drugs on serum levels of brain natriuretic peptide (BNP) was examined in patients with essential hypertension. METHODS: Antihypertensive drugs were administered to 88 hypertensive patients (44 diabetic and 44 nondiabetic) whose systolic blood pressure was greater than 140 mmHg and/or diastolic blood pressure was greater than 90 mmHg. Other antihypertensive drugs were added every two months until the blood pressure fell below 130/85 mmHg. Candesartan, benidipine, bisoprolol or celiprolol, and bunazosin were administered in this order. RESULTS: The mean systolic blood pressure was reduced from 163.7+/-11.6 mmHg to 121.8+/-7.5 mmHg after 12 months in patients with diabetes and from 167.6+/-12.3 mmHg to 122.8+/-7.5 mmHg in patients without diabetes. The mean diastolic blood pressure was also significantly reduced in patients with and without diabetes. Serum BNP levels were reduced from 52.2+/-38.8 pg/mL to 38.8+/-30.9 pg/mL in patients with diabetes and from 47.1+/-34.2 pg/mL to 35.8+/-22.5 pg/mL in patients without diabetes. In patients older than 70 years of age, serum BNP levels were reduced from 56.3+/-39.3 pg/mL to 40.2+/-23.0 pg/mL in those with diabetes and from 54.6+/-32.9 pg/mL to 38.0+/-16.0 pg/mL in those without diabetes. CONCLUSIONS: These results indicate that combination therapy with antihypertensive drugs is usually necessary to reduce blood pressure to below 130/85 mmHg and to improve serum BNP levels.

Blockade of the renin-angiotensin system attenuates sarcolemma and sarcoplasmic reticulum remodeling in chronic diabetes.

Although the defects in the sarcolemma (SL) and sarcoplasmic reticulum (SR) membranes are known to be associated with cardiac dysfunction in chronic diabetes, very little information regarding the mechanisms of these membrane abnormalities is available in the literature. For this reason, rats were treated daily for 8 weeks with and without enalapril, an angiotensin-converting enzyme inhibitor, or losartan, an angiotensin receptor antagonist, 3 days after inducing diabetes with an injection of streptozocin. Treatment of diabetic animals with both enalapril and losartan attenuated alterations in cardiac function and the left ventricular redox potential without any changes in the increased plasma glucose or reduced plasma insulin levels. The SL Na+-K+ ATPase, Ca2+ pump, Na+-dependent Ca2+-uptake, Ca2+-channel density, and low-affinity Ca2+-binding activities were depressed whereas Ca2+ ecto-ATPase activity was increased in the diabetic heart. Furthermore, the SR Ca2+-release and Ca2+-pump activities in the diabetic hearts were decreased without any changes in the Mg2+-ATPase activity. These alterations in SL and SR membranes in diabetic animals were partly prevented by treatments with enalapril and losartan. The results suggest that the activation of the renin-angiotensin system plays an important role in diabetes-induced changes in SL and SR membranes as well as cardiac function.

Cardiovascular disorders in patients with diabetes mellitus.

Diabetes mellitus is a disease with multiorgan involvement. Besides retinopathy, nephropathy and peripheral neuropathy induced by microangiopathy, both cardiovascular and cerebrovascular complications are significant. Both cardiomyopathy and coronary artery disease are observed in patients with diabetes, and the latter is clinically more important because of its high incidence and seriousness.

Alterations of sarcolemmal phospholipase D and phosphatidate phosphohydrolase in congestive heart failure.

Phospholipase D 2 (PLD2) is the major PLD isozyme associated with the cardiac sarcolemmal (SL) membrane. Hydrolysis of SL phosphatidylcholine (PC) by PLD2 produces phosphatidic acid (PA), which is then converted to 1,2 diacylglycerol (DAG) by the action of phosphatidate phosphohydrolase type 2 (PAP2). In view of the role of both PA and DAG in the regulation of Ca(2+) movements and the association of abnormal Ca(2+) homeostasis with congestive heart failure (CHF), we examined the status of both PLD2 and PAP2 in SL membranes in the infarcted heart upon occluding the left coronary artery in rats for 1, 2, 4, 8 and 16 weeks. A time-dependent increase in both SL PLD2 and PAP2 activities was observed in the non-infarcted left ventricular tissue following myocardial infarction (MI); however, the increase in PAP2 activity was greater than that in PLD2 activity. Furthermore, the contents of both PA and PC were reduced, whereas that of DAG was increased in the failing heart SL membrane. Treatment of the CHF animals with imidapril, an angiotensin-converting enzyme (ACE) inhibitor, attenuated the observed changes in heart function, SL PLD2 and PAP2 activities, as well as SL PA, PC and DAG contents. The results suggest that heart failure is associated with increased activities of both PLD2 and PAP2 in the SL membrane and the beneficial effect of imidapril on heart function may be due to its ability to prevent these changes in the phospholipid signaling molecules in the cardiac SL membrane.

Imidapril treatment improves the attenuated inotropic and intracellular calcium responses to ATP in heart failure due to myocardial infarction.

1. Adenosine 5'-triphosphate (ATP) is known to augment cardiac contractile activity and cause an increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) in isolated cardiomyocytes. However, no information regarding the ATP-mediated signal transduction in the myocardium in congestive heart failure (CHF) is available. 2. CHF due to myocardial infarction (MI) in rats was induced by the occlusion of the left coronary artery for 8 weeks. The positive inotropy due to ATP was depressed in failing hearts. Treatment of 3 weeks infarcted animals with imidapril (1 mg kg(-1) day(-1)) for a period of 5 weeks improved the left ventricle function and decreased the attenuation of inotropic response to ATP. 3. ATP-induced increase in [Ca(2+)](i) was significantly depressed in cardiomyocytes isolated from the failing heart and this change was partially attenuated by imidapril treatment. However, the binding characteristics of (35)S-labeled adenosine 5'-(gamma-thio) triphosphate in sarcolemma isolated from the failing heart remained unaltered. 4. ATP-induced increase in [Ca(2+)](i) was depressed by verapamil and cibacron blue in both control and failing heart cardiomyocytes; however, the ATP response in the failing hearts, unlike the control preparations, was not decreased by ryanodine. This insensitivity to ryanodine was attenuated by imidapril treatment. 5. Treatment of infarcted rats with enalapril and losartan produced effects similar to imidapril. 6. These findings indicate that the positive inotropic response to ATP and ATP-induced increase in [Ca(2+)](i) in cardiomyocytes are impaired in heart failure. Furthermore, blockade of renin angiotensin system prevented the impairment of the ATP-mediated inotropic and [Ca(2+)](i) responses in the failing heart.

Roles of MMP-2/-9 in cardiac dysfunction during early multiple organ failure in an ovine animal model.

Biventricular dilation and severe cardiac dysfunction are observed during septic shock. However, when endotoxemia and vasoconstrictor-masked hypovolemia work in concert in the pathogenesis of shock, the clinical scenario is more adverse compared to one of the insults acting alone. Matrix metalloproteinases (MMPs) are involved in chronic and acute heart failure by degrading the mechanical scaffold of the heart and several intracellular proteins. Therefore, the roles of MMP-2, MMP-9, MT1-MMP, focal adhesion kinase (FAK), and Paxillin in hearts of early multiple organ failure induced by norfenefrine-masked hypovolemia and endotoxemia were investigated in an ovine model. Experimental groups included (1) norfenefrine-masked hypovolemia plus endotoxemia (NMH+ENDO) (n=6), (2) norfenefrine-masked hypovolemia without endotoxemia (NMH) (n=6), (3) recurrent endotoxemia during normovolemia (ENDO) (n=6), and (4) healthy untreated controls (CON) (n=3). Apoptosis was determined by TUNEL-staining. Gel zymography revealed significantly increased MMP-2 activity in NMH+ENDO compared to ENDO and controls. MMP-9 activity was significantly elevated in all experimental groups. MMP-2 was significantly increased at the protein level, while MMP-9 was unaltered. MT1-MMP was not significantly changed in any group. Increased MMP activities were associated with cardiac deterioration. MMP-2/-9 activity and phosphorylated Paxillin (p-Paxillin) expression correlated positively with cardiomyocyte apoptosis. This study underscores the pivotal roles of MMP in acute cardiac dysfunction during early multiple organ failure in combined vasoconstrictor-masked hypovolemic and endotoxemia shock.

Risk factors for coronary artery sclerosis in patients with diabetes.

OBJECTIVE: To examine risk factors for coronary artery sclerosis in patients with diabetes mellitus. METHODS: Patients with diabetes were divided into two groups based on whether their electrocardiogram (ECG) showed ischemic changes. In addition to traditional risk factors, other parameters (ie, serum levels of serotonin, homocysteine, thrombomodulin, plasminogen activator inhibitor-1, tissue plasminogen activator, vascular endothelial growth factor, intercellular adhesion molecule-1, vascular cell adhesion molecule-1 and endothelial-leukocyte adhesion molecule-1) were measured in both groups. RESULTS: In the group with ischemic ECG changes (n=13), systolic blood pressure was significantly higher than in the group with no changes (n=18). There were no significant differences in the serum levels of other factors; however, body mass index, hemoglobin A1c, total cholesterol, low density lipoprotein cholesterol and triglyceride levels tended to be higher in the group with ischemic ECG changes. CONCLUSIONS: Although the sample of patients was limited, these results suggest that strict control of traditional risk factors, especially high blood pressure, is important for preventing coronary artery sclerosis in patients with diabetes mellitus.

[Clinical biochemical evaluation of central fatigue with 24-hour continuous exercise].

OBJECTIVE: The present study was conducted to clarify the effects of ultra-marathon (ultra long-term aerobic exercise in which people run long distances) on the brain; examine the issue of central fatigue; verify the serotonin hypothesis of exercise-induced brain fatigue, and ascertain relationships between central fatigue and oxidative stress. METHODS: Subjects consisted of 15 individuals (12 men, 3 women) who ran continuously for 24 h. Mean age was 44 +/- 9 years (range, 31 approximately 64 years). Blood tests were conducted: (1) before starting to run (around 09:00); (2) 16h after starting (02:00 the next day); and (3) just after the finish (around 10:00 the next day) to measure the serum levels of serotonin, melatonin, free tryptophan (f-Tp) and free fatty acid. At the same time, urine samples were collected to measure levels of urinary biopyrrins (BPn). Subjective symptoms were investigated using the Japanese version of the Profile of Mood States (POMS) instrument. RESULTS: (1) Participants ran a mean (+/- SD) distance of 162.6 +/- 18.3 km. (2) There were not marked changes in serum serotonin levels. Serum melatonin levels at 3 time points were 3.4 +/- 0.6 pg/ml, 57.2 +/- 15.2pg/ml and 7.8 +/- 8.9pg/ml, respectively(p < 0.01 before start vs. 16h after start). Serum f-Trp levels at the 3 time points were 5.4 +/- 0.9 nmol/ml, 9.7 +/- 2.1 nmol/ml and 11.5 +/- 4.9 nmol/ml, respectively (p< 0.05 before start vs. just before finish). Free fatty acid levels were 0.42 +/- 0.10 nmol/ml, 1.26 +/- 0.11 nmol/ml and 1.39 +/- 0.23 nmol/ml, respectively (p < 0.01 before start vs. 16 hours after start) (p < 0.05 before start vs. just after finish). (3) Urinary BPn levels increased with time, from 1.2 +/- 0.7 nmol/ml to 2.6 +/- 1.0 nmol/ml to 4.0 +/- 1.5 nmol/ml, respectively (p < 0.01 before the start vs. 16 hours after the start). (4) In terms of POMS scores, fatigue score (Factor F) increased, but vitality score (Factor V) was high at all time points and did not demonstrate any marked changes. Scores for anger and hostility were low (Iceberg profile-type: convex type). Urinary BPn levels were correlated significantly with both serum f-Trp level and Factor F:(y = 8.41x + 2.5, r = 0.708, n = 42) and (y = 2.82x + 5.9, r = 0.568, n = 42), respectively. Urinary BPn thus reflected the degree of subjective fatigue with a high level of sensitivity. CONCLUSIONS: The present results suggest that running continuously for 24h induces brain fatigue and that oxidative stress may be involved.

Dynamic regulation of MEK/Erks and Akt/GSK-3beta in human end-stage heart failure after left ventricular mechanical support: myocardial mechanotransduction-sensitivity as a possible molecular mechanism.

OBJECTIVE: Left ventricular assist devices (LVAD) are used to 'bridge' patients with end-stage heart failure to transplantation. After long-term LVAD support, ventricular function may partially recover, a process called 'reverse remodeling'. As several kinase-mediated signal transduction pathways have been implicated in the development of cardiac hypertrophy and failure, we examined the activities of the Erks, MEKs, Akt, GSK-3 beta, p70S6K, JNKs and p38 under LVAD support as well as during single myocyte strain and whole heart stretch. METHODS: Western blotting and immunohistochemistry were performed using phospho-specific antibodies in matched samples from ten patients with end-stage heart failure before and after LVAD. Cyclic strain was performed in rat neonatal cardiac myocytes, and tensile stretch applied to Langendorff-perfused mouse hearts via a left ventricular balloon. RESULTS: The activity of Erks and Akt in failing hearts dramatically decreased after LVAD support, while that of GSK-3 beta increased. There was an endo/epicardial gradient for Erk activity which persisted after LVAD despite the reduction of total Erk activity. TUNEL-positivity and myocyte size decreased after LVAD, but independently of changes in kinase activity. In cardiomyocytes and Langendorff-perfused mouse hearts both strain/stretch and its relief regulated the activities of Erks, Akt, and GSK-3 beta. CONCLUSION: Erks and Akt/GSK-3 beta are highly responsive to myocyte stretch in vitro and in vivo, and may be sensitive molecular parameters of 'reverse remodeling' under LVAD support.

Cardiomyopathy: molecular and immunological aspects (review).

Idiopathic cardiomyopathy is reviewed from molecular standpoint. About a half of all patients with hypertrophic cardiomyopathy show intra-familial occurrence. In familial hypertrophic cardiomyopathy, nine gene abnormalities have been discovered in the sarcomere, i.e. the genes of beta cardiac myosin heavy chain, cardiac troponin T, alpha-tropomyosin, cardiac myosin binding protein-C, essential or regulatory myosin light chain, cardac troponin I, alpha-cardiac actin, and titin. Sudden death can occur in patients with familial-type hypertrophic cardiomyopathy with abnormalities of the cardiac troponin T or troponin I gene, even if hypertrophy is not marked. Some cases of familial dilated cardiomyopathy show gene abnormalities for cytoskeletal components such as desmin and laminin A/C. Mutations of the delta-sarcoglycan gene have also been discovered in familial or sporadic dilated cardiomyopathy. Mutations in mitochondrial genes have been observed in both hypertrophic and dilated cardiomyopathy. It is postulated that chronic viral myocarditis may sometimes lead to dilated cardiomyopathy, and hepatitis C virus is also thought to be an etiological factor. Immunological abnormalities have also been reported, such as autoantibodies against myosin, beta-receptors, ADP/ATP carrier proteins.

Blockade of 5-HT(2A) receptors by sarpogrelate protects the heart against myocardial infarction in rats.

BACKGROUND: It has been shown that serotonin (5-hydroxytryptamine, 5-HT) is involved in exacerbating vascular abnormalities; however, its role in mediating changes in cardiac function due to myocardial injury has yet to be established. This study examined the effect of sarpogrelate, a 5-HT(2A) receptor blocker, in preventing cardiac dysfunction due to myocardial infarction (MI). METHODS AND RESULTS: Rats were treated 3 days before surgery with or without 5 mg x kg(-1) x day(-1) sarpogrelate, and the left coronary artery was ligated for 3 weeks to induce MI. Sarpogrelate reduced the mortality from 40% to 30%, infarct size from 35% to 25%, and left ventricular end diastolic pressure from 15 mm Hg to 10 mm Hg in MI rats. Electrocardiographic (ECG) tracings showed a marked deviation in the ST-segment and prolongation of the QTc interval in MI rats during the 3 weeks; these changes were attenuated by sarpogrelate pretreatment. In another set of experiments, MI rats were treated with 5 mg x kg(-1) x day(-1) sarpogrelate 1 hour after the surgery, and the hemodynamic and electrocardiograph changes were assessed at 3 weeks. This posttreatment was also found to reduce infarct size, improve cardiac function, and attenuate ECG changes. CONCLUSIONS: Sarpogrelate attenuates cardiac dysfunction, infarct size, and changes in the ECG due to MI. These results also support the view that serotonin and 5-HT(2A) may contribute to the deleterious effects of ischemic injury in the heart.

Increase of ABCG2/BCRP+ side population stem cells in myocardium after ventricular unloading.

BACKGROUND: A significant decrease in mean cardiomyocyte DNA content and increased numbers of diploid cardiomyocytes after unloading has been demonstrated, suggesting a numerical increase of cardiomyocytes. Despite a thorough search in that study, no mitoses explaining a potential net increase of cardiomyocytes has been observed. The heart harbors several stem cell populations, including c-kit (CD117)(+) stem cells and side population cells (SPC), which may proliferate after unloading and thus contribute to the generation of diploid cardiomyocytes. In this study we sought to determine, whether there is an increase of ABCG2(+) SPC and CD117(+) stem cells after unloading. METHODS: In paired myocardial samples (prior to and after LVAD), the number of cells with immunoexpression of ABCG2, c-kit/CD117 and MEF-2 was assessed by immunohistochemistry. Their number was morphometrically determined and these data were correlated with the mean cardiomyocyte DNA content. RESULTS: A significant increase of SPC and cells with coexpression of c-kit and MEF-2 after unloading was observed from 0.00013% in CHF to 0.0011%, and 0.013% to 0.035%, respectively after unloading (p = 0.001). A significant positive correlation between both SPC and cells with coexpression of c-kit and MEF-2 expression was observed (p = 0.007 and 0.01). No correlation was found between the number of SPC and the mean cardiomyocyte DNA content. CONCLUSIONS: SPC are increased significantly in the myocardium after ventricular unloading, suggesting a role for stem cell proliferation during "reverse cardiac remodeling." These cells might proliferate and commit to different cell lineages, such as cardiomyocytes or endothelium, and thus ameliorate cardiac function.