Endothelium-dependent vasorelaxant effect of procyanidin B2 on human internal mammary artery

The aim of the present study was to investigate and characterize vasorelaxant effect of procyanidin B2 on human internal mammary artery (HIMA) as one of the mechanisms of its protective effect against vascular risk. Procyanidin B2 induced strong concentration-dependent relaxation of HIMA rings pre-contracted by phenylephrine. Pretreatment with L-NAME, a NO synthase inhibitor, hydroxocobalamin, a NO scavenger, and ODQ, an inhibitor of soluble guanylate cyclase, significantly inhibited procyanidin B2-induced relaxation of HIMA, while indomethacin, a cyclooxygenase inhibitor, considerably reduced effects of low concentrations. Among K+ channel blockers, iberiotoxin, a selective blocker of large conductance Ca2+-activated K+ channels (BKCa), abolished procyanidin B2-induced relaxation, glibenclamide, a selective ATP-sensitive K+(KATP) channels blocker, induced partial inhibition, while 4-aminopyridine, a blocker of voltage-gated K+(KV) channels, and TRAM-34, an inhibitor of intermediate-conductance Ca2+-activated K+(IKCa) channels, slightly reduced maximal relaxation of HIMA. Further, procyanidin B2 relaxed contraction induced by phenylephrine in Ca2+-free Krebs solution, but had no effect on contraction induced by caffeine. Finally, thapsigargin, a sarcoplasmic reticulum Ca2+-ATPase inhibitor, significantly reduced relaxation of HIMA produced by procyanidin B2. These results demonstrate that procyanidin B2 produces endothelium-dependent relaxation of HIMA pre-contracted by phenylephrine. This effect is primarily the result of an increased NO synthesis and secretion by endothelial cells and partially of prostacyclin, although it involves activation of BKCa and KATP, as well as KV and IKCa channels in high concentrations of procyanidin B2.

Greater vasopressin-induced vasoconstriction and inferior effects of nitrovasodilators and milrinone in the radial artery than in the internal thoracic artery

BACKGROUND

Vasopressin may be a potential cause of spasm in both the radial artery and the internal thoracic artery. This study compared the vasopressin-induced contraction and the effects of milrinone, nitroglycerin, and nitroprusside in vasopressin-induced contraction between the human radial artery and the internal thoracic artery to find effective antispastic methods for arterial grafts.

METHODS

Concentration-contraction (normalized as force gram produced by each millimeter of the circumference tissue of the artery) curves for vasopressin with or without pretreatment of vasodilators and concentration-relaxation curves for the vasodilators listed were established in the human radial artery (n = 107) and internal thoracic artery (n = 122) segments.

RESULTS

Vasopressin induced a greater contraction in the radial artery than in the internal thoracic artery (1.9 +/- 0.2 g/mm vs 0.6 +/- 0.1 g/mm, P < .001) with a higher sensitivity (lower EC(50): -9.28 +/- 0.11 vs -8.91 +/- 0.05 log(10)M, P = .006). Milrinone was less potent than nitroglycerin and nitroprusside with higher EC(50) (P < .05) in both the internal thoracic artery and radial artery. Pretreatment with milrinone and nitroprusside significantly inhibited vasopressin contraction in the internal thoracic artery but had little effect in the radial artery. Pretreatment with nitroglycerin did not significantly inhibit the maximum vasopressin contraction in either the internal thoracic artery or radial artery.

CONCLUSION

The radial artery is more prone to develop spasm related to vasopressin than is the internal thoracic artery, and the effect of vasodilators in vasopressin-induced contraction is different in the radial artery from that in the internal thoracic artery. A more significant prophylactic antispastic effect of milrinone and nitroprusside is demonstrated in the internal thoracic artery than in the radial artery. Therefore, more intensive antispastic treatment is necessary in the radial artery than in the internal thoracic artery during coronary artery bypass grafting.

Comparison of nitroprusside and nitroglycerin in inhibition of angiotensin II and other vasoconstrictor-mediated contraction in human coronary bypass conduits

AIMS

To compare the effect of nitroprusside (SNP) and nitroglycerin (NTG) on angiotensin II (ANGII), endothelin-1 (ET-1), and alpha1-adrenoceptor (phenylephrine, PE)-mediated contraction in internal mammary artery (IMA).

METHODS

Human IMA segments (n=120) taken from 37 patients were studied. Concentration-relaxation curves for SNP and NTG were established in IMA precontracted with these vasoconstrictors. Concentration-contraction curves were also constructed in IMA rings incubated with SNP and NTG (0.1 and 1 microM) for 10 min.

RESULTS

Both SNP and NTG caused full relaxation with similar EC50s except NTG was four-fold more potent than SNP in PE-induced contraction (-7.92 +/- 0.06 vs -7.32 +/- 0.2 log M, mean +/- s.e. mean, P<0.01; 95% confidence interval for the difference of the means: 0.19, 1.01 log M). Pretreatment with SNP (0.1 and 1 microM) significantly depressed the contraction by ANGII from 56.6 +/- 7.7% (of 100 mM K+-contraction) to 18.3 +/- 8.6% and 3.9 +/- 2.1% (P=0.0001). In four rings treated with SNP, the contraction to ANGII was abolished whereas NTG did not depress ANGII-mediated contraction. Pretreatment with SNP (1 microM), but not NTG, significantly depressed the magnitude of the PE-induced contraction from 4.7 +/- 1.2 to 1.7 +/- 0.4 g (P<0.05). Treatment with both SNP and NTG significantly increased the EC50 (-5.09 +/- 0.17 log M, P=0.0007 for SNP and -5.40 +/- 0.06 log M, P=0.02 for NTG). Pretreatment with SNP did not significantly change either the magnitude or the EC50 of the ET-1-induced contraction.

CONCLUSIONS

SNP may be advantageous compared with NTG in preventing coronary arterial graft contraction. However, once grafts have constricted to ANGII, alpha1-adrenoceptor agonists, and ET-1, NTG may be only marginally advantageous.

Bioassay of endothelium‐derived hyperpolarizing factor with abolishment of nitric oxide and the role of gap junctions in the porcine coronary circulation

Previous bioassays of endothelium‐derived hyperpolarizing factor (EDHF) were partially related to the residual nitric oxide (NO) resistant to NO synthase inhibitors. Further, the role of gap junctions in EDHF is controversial. We performed a bioassay of EDHF with abolishment of NO production by using the NOS inhibitor NG‐nitro‐l‐arginine (l‐NNA) plus the NO scavenger hemoglobin (Hb) and examined the role of gap junctions/K+ channels related to EDHF in porcine coronary large and microarteries in an organ chamber/myograph. Bradykinin (BK)‐induced EDHF‐mediated relaxation and hyperpolarization (by a microelectrode) were studied with indomethacin (7 µM), l‐NNA (300 µM), and Hb (20 µM). NO concentrations ([NO]) were measured electrochemically. In large coronary arteries, BK increased [NO] (9.3±1.7 nM vs. 166.7±18.3 nM, P<0.01) that was significantly reduced by l‐NNA (49.3±7.8 nM, P<0.01) and eliminated by Hb, and hyperpolarized the downstream endothelium‐denuded artery by 9.0±1.4 mV (P<0.01) that was reduced but not abolished by l‐NNA and Hb (5.6±0.7 mV, P<0.01). In microarteries, elimination of NO decreased but did not abolish the hyperpolarization (−63.8±1.5 mV vs. −56.9±1.6 mV, P=0.01) and relaxation (70.2±5.7% vs. 42.3±4.4%, P<0.01). Charybdotoxin (0.1 µM) and apamin (0.5 µM), but neither glybenclimide (3 µM) nor gap junction inhibitors (18α‐glycyrrhetinic acid, 1‐heptanol, and gap 27) reduced the EDHF‐mediated response. We conclude that in porcine coronary arteries, with the abolishment of NO by NOS inhibitors plus the NO scavenger Hb, the non‐NO EDHF exists and is transferable from an endothelium‐intact artery to an endothelium‐denuded artery. Compared with the significant involvement of calcium‐activated K+ channels, the gap junctions may only play a minimal role in the EDHF‐mediated response even in the microcirculation of the porcine coronary artery. Drug Dev. Res. 58:99–110, 2003. © 2003 Wiley‐Liss, Inc.

Heart valve replacement surgery: past, present and future

1. The present review covers the historical and present role of valvular surgery in treating heart disease and speculates what the future may be in this very important field of cardiac surgery. 2. One of the important elements of tissue valve replacement is durability and how to analyse the valves mathematically, so that the projected durability could be described from the observed period to an extended period. We found that the Weibull distribution is a very good mathematical method of describing the deterioration of tissue valves. 3. We also can see a very marked difference among different pericardial valves. The Carpentier-Edwards pericardial valve has tremendous durability compared with the previous generation of pericardial valves, namely the Ionescu-Shiley. 4. The incidence of structural valve deterioration varies according to the age of the patient at the time of implant. A very important feature to analyse in making a clinical decision with regard to the type of valve to implant is the age of the patient at the time of implantation, because this determines their long-term survival. 5. Another very important feature of valve replacement is the problem of valve thrombosis. This was the problem that we encountered in experimental animals and why it is so difficult to obtain a long-term survivor with mechanical valve replacement in dogs. Now, in humans, the incidence of thrombosis of these artificial valves is extremely low. 6. Another important feature of valve replacement is the incidence of late thromboembolism (TE). Differences in reports using the same valve are greater than differences between different prostheses and the average is approximately 1.5-2%/year incidence of TE. 7. We can conclude from this review that there has been significant progress in diminishing operative mortality and enhanced long-term survival following valve replacement over the past four decades. Increased durability of tissue valves has now become apparent, from the earliest application to the current time with glutaraldehyde-preserved pericardial valves. The late complication rates are approximately the same with all valve types, except that there is a dimunition in the possibility for valve thrombosis for tissue valves versus mechanical valves. Finally, anticoagulation continues to be required for mechanical valve replacement and we still require more durable tissue valves and freedom from anticoagulation for mechanical valves.

Altered endothelium-derived hyperpolarizing factor-mediated endothelial function in coronary microarteries by St Thomas' Hospital solution

OBJECTIVES

We examined the effect of St Thomas' Hospital solution on endothelium-derived hyperpolarizing factor-mediated function in the porcine coronary microarteries with emphasis on the effect of temperature and washout time.

METHODS

Microartery rings (diameter, 200-450 micrometers) were studied in myograph. The arteries were incubated in St Thomas' Hospital or Krebs solution (control) at 4 degrees C for 4 hours followed by 45 minutes (group Ia) or 90 minutes washout (group Ib) or at 22 degrees C for 1 hour followed by 45 minutes (group IIa) or 90 minutes washout (group IIb) and precontracted with -8.5 log M U 46619. The endothelium-derived hyperpolarizing factor-mediated relaxation to bradykinin was studied when endothelium-derived nitric oxide and prostaglandin I2 were inhibited with the presence of 7 micromol/L indomethacin and 300 micromol/L NG-nitro-L -arginine.

RESULTS

After exposure to St Thomas' Hospital solution, the maximal endothelium-derived hyperpolarizing factor-mediated relaxation (percentage of the precontraction) was significantly reduced at either temperature after washout for 45 minutes (group Ia, 42.7% +/- 3.5% vs 69.0% +/- 5.3%; n = 9; P =.000; and group IIa, 12.3% +/- 1.6% vs 56.1% +/- 4. 4%; n = 8; P =.000) but fully recovered after washout for 90 minutes. The U46619-induced contraction force was also significantly reduced after washout for 45 minutes (P <.001) but fully recovered at 90 minutes.

CONCLUSIONS

Under profound and moderate hypothermia, St Thomas' Hospital solution impairs endothelium-derived hyperpolarizing factor-mediated relaxation and smooth muscle contraction in the coronary microarteries. These effects exist during the reperfusion period for at least 45 minutes after exposure to St Thomas' Hospital solution and may account for the possible myocardial dysfunction during reperfusion.

Tetramethylpyrazine suppresses angiotensin II-induced soluble epoxide hydrolase expression in coronary endothelium via anti-ER stress mechanism

Activation of soluble epoxide hydrolase (sEH) is associated with endothelial dysfunction in hypertension, though the underlying mechanisms are inadequately understood and the role of endoplasmic reticulum (ER) stress is yet to be studied in detail. Tetramethylpyrazine (TMP), a major bioactive ingredient of Chinese herb Chuanxiong, is well-known for its cardiovascular benefits. Nevertheless, whether TMP may protect vascular endothelium from ER stress and whether regulation of sEH is involved remain unknown. This study aimed at investigating the role of ER stress in angiotensin-II (Ang-II)-induced sEH dysregulation and elucidating the significance of ER stress regulation in the vasoprotective effect of TMP. Porcine primary coronary artery endothelial cells (PCECs) were used for western blot, ELISA, and reverse-transcription PCR analysis. Porcine coronary arteries were assessed in a myograph for endothelial dilator function. Ang-II induced expression of ER stress molecules in PCECs meanwhile enhanced sEH expression and decreased 11,12-EET. Exposure of PCECs to the chemical ER stress inducer tunicamycin also increased sEH expression. Inhibition of ER stress suppressed sEH upregulation, resulting in an increase of 11,12-EET. The impairment of endothelium-dependent vasorelaxation induced by Ang-II or tunicamycin was ameliorated by inhibitors of ER stress or sEH. TMP showed comparable inhibitory effect to ER stress inhibitors on the expression of ER stress molecules, the dysregulation of sEH/EET, and the impairment of endothelial dilator function. We demonstrated that ER stress mediates Ang-II-induced sEH upregulation in coronary endothelium. TMP has potent anti-ER stress capacity through which TMP normalizes sEH expression and confers protective effect against Ang-II on endothelial function of coronary arteries.

Endothelial function related to vascular tone in cardiac surgery

Vascular endothelium has multiple functions including regulating of vascular tone, preventing platelet aggregation, anti-proliferation, etc. An intact endothelial function is essential to the maintenance of an adequate vascular tone, to prevent platelet aggregation in the intimal surface of blood vessels, to prevent smooth muscle proliferation, and to prevent atherosclerosis. This review focuses on endothelial function related to the vascular tone in cardiac surgery. The review is composed by three sections. In the first section, normal endothelial function related to vascular tone is described. In the second section, coronary endothelial function related to cardiac arrest and cardioplegic exposure is reviewed. In the third section, the endothelial function in the coronary bypass grafts is summarised. It is particularly important to understand that coronary endothelial dysfunction may be one of the major causes of low perfusion of the myocardium after cardiac arrest or donor heart preservation. Further, endothelium plays a major role in the maintenance of vascular tone and in the long-term patency of CABG grafts. The characteristics of endothelium in arterial and venous grafts and the correlation to the long-term patency are now more understood. A number of methods have been suggested to protect endothelial function in either coronary circulation or in coronary artery bypass grafts during cardiac surgery but further investigations in this field are warranted.

Aortic valve replacement in elderly patients: influence of concomitant coronary grafting on late survival

BACKGROUND

Aortic valve replacement (AVR) has been an accepted therapy for elderly patients (> 70 years) with aortic valve disease. This study was designed to investigate the determinants of survival after the implantation of aortic valve prostheses, with emphasis on the effect of concomitant coronary artery bypass grafting on survival.

METHODS

From November 1964 to July 1994,963 elderly patients underwent isolated AVR. Long-term survival was investigated in 877 patients (70 to 94 years) who survived operation, with 92% follow-up completeness (mean +/- standard deviation, 4.5 +/- 3.9 years; maximum, 20.1 years; total, 3,920.2 patient-years), by univariate and multivariate analyses.

RESULTS

Actuarial survival was 38.1% +/- 2.8% at 10 years, 17.8% +/- 3.0% at 15 years, and 9.0% +/- 3.1% at 20 years. Eight variables (age, sex, body surface area [less or greater than 1.7 m2], period of operation, type of prosthesis, size of prosthesis, re-replacement, and concomitant coronary artery bypass grafting) were investigated with regard to long-term survival by the Kaplan-Meier method. Age, sex, and body surface area were significant. Multivariate analysis revealed that older age (p = 0.0005) and male sex (p = 0.0001) were independent variables that determined long-term survival.

CONCLUSIONS

Elderly patients may have satisfactory long-term results after AVR. Age and sex are independent determinants. Other factors (such as concomitant coronary artery bypass grafting and type of prosthesis) did not independently influence long-term survival. Coronary revascularization in elderly patients with coronary disease undergoing AVR may lead to a long-term survival similar to that in patients without coronary disease undergoing AVR.

Increased serum concentrations of asymmetric dimethylarginine (ADMA) in patients with early-onset coronary artery disease

BACKGROUND

Asymmetric dimethylarginine (ADMA) has been associated with an increased risk of cardiovascular disease. We investigated the role of serum ADMA concentrations in early-onset coronary artery disease (EOCAD).

METHODS

Candidates for coronary artery angiography (age<50y for men and <55y for women) who met the inclusion criteria were enrolled in this study. Serum concentrations of ADMA were determined using ELISA. Severity of coronary atherosclerosis was estimated by number of diseased vessels.

RESULTS

A total of 601 subjects (286 with EOCAD patients and 315 controls) were included in the study. ADMA concentrations were found to be significantly higher in the EOCAD group (0.480±0.110μmol/l) than in the control group (0.457±0.091, P=0.007). ADMA concentrations significantly increased with the number of diseased vessels (P<0.001). In addition, serum ADMA concentrations were affected by diabetes mellitus and smoking status, and were positively correlated with serum creatinine and body mass index (BMI).

CONCLUSIONS

Our results show that serum ADMA concentrations were associated with the presence and severity of EOCAD, suggesting that ADMA may be involved in the progression of EOCAD.

Role of TRPC3 channel in human internal mammary artery

BACKGROUND AND AIMS

Intracellular calcium regulation in endothelial cells depends on transient receptor potential channels (TRPs). Canonical TRPs (TRPCs) are now recognized as the most important Ca(2+)-permeable cation channels in vascular endothelium and TRPC3 channel is reported to play a role in vasodilation in animal vessels. However, little is known about the role of TRPCs in human arteries. We therefore tested the hypothesis that TRPCs play a role in human arteries.

METHODS

Cumulative concentration-relaxation curves to acetylcholine (-11 to -4.5 log M) were established in the human internal mammary artery (IMA) rings (n = 42) taken from 28 patients undergoing coronary artery bypass grafting in precontraction induced by U46619 (-8 log M) in the absence or presence of SKF96365 (10 μmol/L) or Pyr3 (3 μmol/L). Protein expressions of TRPC3 were determined by Western blot and immunohistochemistry staining.

RESULTS

The maximal relaxation induced by acetylcholine was significantly attenuated by the nonspecific cation channels inhibitor, SKF96365 (48.2 ± 3.7 vs. 66.0 ± 0.9% in control, p <0.01) or the selective TRPC3 blocker, Pyr3 (58.4 ± 2.3% vs. 67.7 ± 1.1% in control, p <0.01). Protein expression of TRPC3 was detected in human IMA.

CONCLUSIONS

TRPC3 exists and plays a role in the acetylcholine-induced endothelium-dependent relaxation in the human IMA. This study suggests that TRPC3 may be a potential new target in endothelial protection in patients with endothelial dysfunction such as in patients with coronary artery disease in order to improve the long-term patency of the grafting vessels.

Preoperative plasma biomarkers associated with atrial fibrillation after coronary artery bypass surgery

OBJECTIVES

Postoperative atrial fibrillation (POAF) is a common complication in coronary artery bypass grafting (CABG) procedures. This prospective study aimed to investigate predisposition of proteins and metabolites correlated to POAF after CABG and related cellular pathways.

METHODS

Preoperative plasma samples from patients undergoing CABG procedures were prospectively collected. After CABG, the patients were grouped to POAF or sinus rhythm (N = 170; n = 90 in the discovery set and n = 80 in the validation set). The plasma samples were analyzed using proteomics, metabolomics, and bioinformatics to identify the differential proteins and differential metabolites. The correlation between differential proteins and POAF was also investigated by multivariable regression analysis and receiver operator characteristic analysis.

RESULTS

In the POAF(+) group, 29 differential proteins and 61 differential metabolites were identified compared with the POAF(-) group. The analysis of integrated omics revealed that preoperative alteration of peroxisome proliferators-activated receptor α and glutathione metabolism pathways increased the susceptibility of POAF after CABG. There was a correlation between plasma levels of apolipoprotein-C3, phospholipid transfer protein, glutathione peroxidase 3, cholesteryl ester transfer protein, and POAF.

CONCLUSIONS

The present study for first time at multi-omics levels explored the mechanism of POAF and validated the results in a new cohort of patients, suggesting preexisting differential proteins and differential metabolites in the plasma of patients prone to POAF after CABG. Dysregulation of peroxisome proliferators-activated receptor α and glutathione metabolism pathways related to metabolic remodeling and redox imbalance-associated electrical remodeling may play a key role in the pathogenesis of POAF. Lower plasma phospholipid transfer protein, apolipoprotein-C3, higher cholesteryl ester transfer protein and glutathione peroxidase 3 levels are linked with POAF. These proteins/metabolites may be developed as biomarkers to predict POAF.

Different role of nitric oxide and endothelium-derived hyperpolarizing factor in endothelium-dependent hyperpolarization and relaxation in porcine coronary arterial and venous system

OBJECTIVE

We compared the basal and bradykinin (BK)-induced NO release and endothelium-derived hyperpolarizing factor-mediated function between coronary arteries and cardiac veins.

METHODS AND RESULTS

Isolated coronary vessels (large arteries, cardiac veins as well as microvessels) were studied. An NO-specific electrode and a conventional intracellular glass microelectrode were used to directly measure NO released from endothelial cells and hyperpolarization of smooth muscle cells in conduit coronary vessels. The basal and BK-induced release of NO was 14.2 +/- 2.0 nmol/L and 237.1 +/- 27.2 nmol/L (n = 8) in the artery, significantly greater than in veins (8.0 +/- 1.1 nmol/L and 135.6 +/- 14.5 nmol/L, n = 8, P < 0.01). The BK-induced hyperpolarization was significantly reduced by N-nitro-L-arginine, indomethacin, and hemoglobin in both arteries and veins and was greater in the arteries. The EDHF-mediated relaxation was significantly higher in the arteries than in veins, greater in microveins than in large veins, and almost abolished by charybdotoxin and apamin.

CONCLUSIONS

Both NO and EDHF are involved in the regulation of the vascular tone in the coronary arterial and venous systems but the amount of NO release and the EDHF-mediated relaxation and associated hyperpolarization are less significant in the vein than in the artery in the coronary system.

Serum Uric Acid as an Independent Risk Factor for the Presence and Severity of Early-Onset Coronary Artery Disease: A Case-Control Study

Serum uric acid (UA) is the final product of purine metabolism in humans. The present study is aimed at identifying the potential association between serum UA and early-onset coronary artery disease (EOCAD). The study population consisted of 1093 EOCAD patients aged ≤50 years, and 1117 age- and sex-matched apparently healthy people served as controls. The concentrations of UA were measured by uricase method. The severity of CAD was evaluated by Gensini score. The mean serum level of UA was 5.843 ± 1.479 mg/dl in EOCAD patients and 5.433 ± 1.529 mg/dl in controls. Serum UA levels were significantly higher in the EOCAD group than those in the control group (P < 0.001) and was an independent risk factor for EOCAD (OR = 1.100, 95% CI: 1.022-1.185). The early-onset myocardial infarction patients with 3-vessel disease had higher serum UA levels than those with 1- or 2-vessel disease. The serum UA levels of EOCAD patients with acute coronary syndrome were significantly higher than those with chronic coronary artery disease. EOCAD patients with hyperuricemia had higher Gensini scores than those without hyperuricemia. In addition, the serum UA levels were affected by drinking (P < 0.01) and were positively correlated with serum creatinine (r = 0.323) and weight (r = 0.327). Our results show that serum UA was an independent risk factor for EOCAD. The serum UA levels were associated with the presence and severity of EOCAD and suggested that UA may be involved in the progression of EOCAD.

Identification of a novel and functional mutation in the TBX5 gene in a patient by screening from 354 patients with isolated ventricular septal defect

Ventricular septal defect (VSD) is the most frequently occurring congenital heart disease in newborns. A number of genetic studies have linked TBX5 mutations to cardiac abnormalities. We aimed to identify potential pathogenic mutations in TBX5 and to provide insights into the etiology of sporadic and isolated VSD. Case-control mutational and functional analyses were performed in 354 sporadic patients with isolated VSD and 341 controls. All the coding exons and intron-exon boundaries of TBX5 were first sequenced in a group of VSD patients and controls. Sanger sequencing with high-resolution melting (HRM) curve analysis in new patients and controls was then used to detect TBX5 mutation and frequency. Luciferase activities were measured to identify transcriptional regulation of TBX5 to MYH6 and ANF promoter. A novel heterozygous missense mutations c.40C > A (p.Pro14Thr) was identified in TBX5 gene exon-2, resulting proline to threonine substitution. TBX5 containing mutation reduced transcriptional activities of the MYH6 promoter but enhanced transcriptional activities of the ANF promoter, compared with the wild type. This novel heterozygous missense mutation in TBX5 gene exon-2 that causes significant changes of the activity of TBX5 is therefore highly possible to be the cause of the defect in the VSD patients.

A new antispastic solution for arterial grafting: nicardipine and nitroglycerin cocktail in preparation of internal thoracic and radial arteries for coronary surgery

OBJECTIVE

Antispastic protocols for arterial grafts are important in arterial grafting for coronary artery bypass grafting surgery. We designed a new nicardipine and nitroglycerin cocktail that is composed of a second-generation dihydropyridine calcium antagonist, nicardipine and nitroglycerin (30 micromol/L), and examined its effect in human internal thoracic and radial arteries.

METHODS

Human internal thoracic (n = 86) and radial (n = 74) artery segments from 72 patients undergoing coronary artery bypass grafting were studied. Relaxation against 3 classic vasoconstrictors (potassium chloride, thromboxane A(2) mimetic U46619, and alpha-adrenoceptor agonist norepinephrine) and prophylactic effect on contraction against these vasoconstrictors were examined. The effect of the nicardipine and nitroglycerin cocktail on the endothelial function in internal thoracic and radial arteries was studied in response to acetylcholine.

RESULTS

Nicardipine and nitroglycerin induced almost full relaxation (92.2% +/- 4.7% to 97.9% +/- 1.0%, P < .001 in internal thoracic arteries and 95.4% +/- 1.9% to 96.7% +/- 3.3%, P < .001 in radial arteries, n = 6-8) against 3 vasoconstrictors with significant prophylactic effect on contraction (maximal contraction was depressed to 32.5% to 76.4%, P < .05 or P < .001, and EC50s were increased to 5 to 42-fold more, P < .01). After treatment with the nicardipine and nitroglycerin cocktail, the acetylcholine-induced relaxation was unchanged (P > .05).

CONCLUSION

The use of the nicardipine and nitroglycerin cocktail provides a new antispastic protocol that has rapid onset, full relaxation, and excellent prophylactic effect against all known mechanisms of vasospasm and maximally protects the endothelial and smooth muscle function of the internal thoracic and radial arteries. The cocktail is therefore expected to provide a new method in treating grafts in coronary artery bypass grafting with the best antispastic effect and protection of the graft.

A new transmyocardial degradable stent combined with growth factor, heparin, and stem cells in acute myocardial infarction

AIMS

We developed a new method-transmyocardial drilling revascularization (TMDR) with absorbable stent incorporated with basic fibroblast growth factor (bFGF) and heparin. The present study tested the effect of this method with transplantation of bone marrow-derived stem cells (BMSCs) in acute myocardial infarction.

METHODS AND RESULTS

Infarction was produced in mini-swine by ligating the left anterior descending (LAD) coronary artery. TMDR of 3.0 mm in diameter was made by mechanical drilling in the infarcted area. The animals that had LAD ligation were divided into six groups according to the procedures followed (n = 6 in each): control; T (TMDR); C (cell implantation); TS (TMDR+stent implantation); TC (TMDR+cell implantation); TSC (TMDR+stent implantation+cell implantation). Left ventricular (LV) function, myocardial perfusion, vascular density, and histological and morphological analyses were evaluated pre-operatively and at 30 min and 6 weeks post-operatively. Six weeks after operation, the above indices were significantly better in the TSC group than in other groups (P < 0.001 compared with the control group, and P < 0.05 or 0.01 compared with the TS and TC groups), although TS and TC also showed better results than the control group (P < 0.05).

CONCLUSION

We have demonstrated in a pig model that an intramyocardial stent implanted with slow release of bFGF, heparin, and BMSC transplantation may significantly increase LV function, cardiac blood flow, and vascular density. Therefore, the present study may provide a new method for the surgical treatment of myocardial infarction.

Role of NO and EDHF-mediated endothelial function in the porcine pulmonary circulation: comparison between pulmonary artery and vein

OBJECTIVE

To compare electrophysiological measurement of nitric oxide (NO) release and endothelium-derived hyperpolarizing factor (EDHF)-mediated endothelial function in porcine pulmonary arteries and veins.

METHODS

Isolated pulmonary interlobular arteries (PA) and veins (PV) were obtained from a local slaughterhouse. By using a NO-specific electrode and a conventional intracellular microelectrode, the amount of NO released from endothelial cells and hyperpolarization of smooth muscle cells were investigated. The bradykinin (BK)-induced relaxation in the precontraction by U(46619) was examined in the absence or presence of N(G)-nitro-l-arginine (l-NNA), indomethacin (INDO) plus oxyhemoglobin (HbO).

RESULTS

The basal release of NO was 7.0+/-1.2 nmol/L in PA (n=8) and 5.5+/-1.6 nmol/L in PV (n=8, p<0.01). BK-induced release of NO was 160.4+/-10.3 nmol/L in PA (n=8) and 103.0+/-14.7 nmol/L in PV (n=8, p<0.001) with longer releasing duration in PA than in PV (14.3+/-1.3 vs. 12.1+/-0.8 min, p<0.01). BK evoked an endothelium-dependent hyperpolarization and relaxation that were reduced by l-NNA, INDO, and HbO (hyperpolarization: 12.8+/-1.3 vs. 8.0+/-1.4 mV in PA, n=6, p<0.001 and 8.3+/-1.4 vs. 3.0+/-0.8 mV in PV, n=6, p<0.001; relaxation: 92.8+/-3.1% vs. 19.6+/-11.1% in PA n=8, p<0.001 and 70.3+/-7.9% vs. 6.0+/-6.8% in PV, n=8, p<0.001). Both hyperpolarization (8.0+/-1.4 vs. 3.0+/-0.8 mV, p<0.001) and relaxation (19.6+/-11.1% vs. 6.0+/-6.8%, p<0.01) were greater in PA than in PV.

CONCLUSIONS

Both NO and EDHF play an important role in regulation of porcine pulmonary arterial and venous tones. The more significant role of NO and EDHF is revealed in pulmonary arteries than in veins.

Dual actions of cilnidipine in human internal thoracic artery: inhibition of calcium channels and enhancement of endothelial nitric oxide synthase

OBJECTIVE

Cilnidipine is a novel, long-action L/N-type dihydropyridine calcium channel blocker that has recently been used for antihypertensive therapy. We investigated the vasorelaxation effect of cilnidipine with regard to its calcium channel blockage and nitric oxide-cyclic guanosine monophosphate-dependent mechanism in human internal thoracic artery.

METHODS

Fresh human internal thoracic arteries taken from discarded tissues of patients undergoing coronary artery bypass surgery were studied. Concentration-relaxation curves for cilnidipine in comparison with nifedipine were studied. The expression level of endothelial nitric oxide synthase mRNA was assayed by quantitative real-time polymerase chain reaction, and the phosphorylation of endothelial nitric oxide synthase at Ser(1177) was determined by Western blotting analysis.

RESULTS

Cilnidipine and nifedipine caused nearly full relaxation in potassium-precontracted internal thoracic artery. Pretreatment with cilnidipine at the clinical plasma concentration significantly depressed the maximal contraction. Endothelium denudation (47.7% ± 7.0%, P < .05) and inhibition of endothelial nitric oxide synthase (48.6% ± 6.1%, P < .05) or guanylate cyclase (41.6% ± 3.8%, P < .01) significantly reduced the cilnidipine-induced endothelium-dependent relaxation (73.9% ± 6.4%). Cilnidipine increased the expression of endothelial nitric oxide synthase mRNA by 42.4% (P < .05) and enhanced phosphorylation level of endothelial nitric oxide synthase at Ser(1177) by 37.0% (P < .05).

CONCLUSIONS

The new generation of calcium channel antagonist cilnidipine relaxes human arteries through calcium channel antagonism and increases production of nitric oxide by enhancement of endothelial nitric oxide synthase. The dual mechanisms of cilnidipine in human arteries demonstrated in this study may prove particularly important in vasorelaxing therapy in cardiovascular diseases.

Effect of 11,12-epoxyeicosatrienoic acid as an additive to St. Thomas' cardioplegia and University of Wisconsin solutions on endothelium-derived hyperpolarizing factor-mediated function in coronary microarteries: influence of temperature and time

BACKGROUND

We examined the effect of 11,12-epoxyeicosatrienoic acid (EET(11,12)) added to St. Thomas' Hospital (ST) solution or University of Wisconsin (UW) solution on endothelium-derived hyperpolarizing factor (EDHF)-mediated relaxation under clinically relevant temperature and exposure time.

METHODS

Porcine coronary microarteries (200 to 450 microm) were incubated with Krebs' solution (control), ST with or without EET(11,12) (300 nmol/L) at 22 degrees C for 1 hour as well as at 4 degrees C for 1 or 4 hours, and UW with or without EET(11,12) at 4 degrees C for 4 hours. The EDHF-mediated relaxation was induced by bradykinin (-10 to approximately -6.5 log M) in the precontraction evoked by U(46619) (10 nmol/L) or U(46619) (1 nmol/L) plus endothelin-1 (6 nmol/L).

RESULTS

The EDHF-mediated relaxation was reduced after exposure to UW (79.7% +/- 4.6% versus 93.6% +/- 2.8%, p = 0.01) at 4 degrees C for 4 hours. One-hour exposure to ST under 22 degrees C or 4 degrees C decreased the relaxation (75.2% +/- 7.6% versus 96.7% +/- 1.6%, p < 0.05) or the sensitivity to bradykinin (-8.04 +/- 0.15 versus -8.50 +/- 0.20 log M, p < 0.05). The relaxation increased to 86.8% +/- 5.3% by addition of EET(11,12) to ST (1 hour at 22 degrees C, p < 0.05) but was unchanged when added to either ST or UW at 4 degrees C for 1 or 4 hours.

CONCLUSIONS

As an additive to ST solution, EET(11,12) may partially restore EDHF-mediated endothelial function under moderate hypothermia but had no significant effect under profound hypothermia when added to either ST or UW solution. Further investigation is necessary to improve the effect.

Chloride Channels are Involved in the Development of Atrial Fibrillation - A Transcriptomic and proteomic Study

Electrical and structural remodeling processes are contributors to the self-perpetuating nature of atrial fibrillation (AF). However, their correlation has not been clarified. In this study, human atrial tissues from the patients with rheumatic mitral valve disease in either sinus rhythm or persistent AF were analyzed using a combined transcriptomic and proteomic approach. An up-regulation in chloride intracellular channel (CLIC) 1, 4, 5 and a rise in type IV collagen were revealed. Combined with the results from immunohistochemistry and electron microscope analysis, the distribution of type IV collagen and effects of fibrosis on myocyte membrane indicated the possible interaction between CLIC and type IV collagen, confirmed by protein structure prediction and co-immunoprecipitation. These results indicate that CLICs play an important role in the development of atrial fibrillation and that CLICs and structural type IV collagen may interact on each other to promote the development of AF in rheumatic mitral valve disease.

Total Flavone of Rhododendron Improves Cerebral Ischemia Injury by Activating Vascular TRPV4 to Induce Endothelium-Derived Hyperpolarizing Factor-Mediated Responses

BACKGROUND

Total flavonoids of Rhododendron (TFR) is extracted from Rhododendron, a herbal medicine widely used in China. The main components are flavone compounds such as warfarin, rutin, quercetin, and hyperoside. We investigated the role of TRPV4 channel in the TFR induced endothelium-dependent hyperpolarizing factor- (EDHF-) mediated responses against ischemia/reperfusion injury (IR) in cerebral IR (CIR) rats.

METHODS

The morphological changes of cerebral cortex, the relaxation of cerebral basal artery (CBA), and cell membrane potential recording were studied in CIR rats. The outward potassium current in smooth muscle cell was recorded by whole-cell patch clamp recording. The protein expression of TRPV4, SKca, and IKca was determined. Confocal laser was used to measure the Ca2+ fluorescence intensity.

RESULTS

After treatment with TFR, the number of pyramidal cells in brain tissue increased and the number of empty or lightly stained cells decreased and these effects were eliminated by using HC-067047, Apamin, or TRAM-34. TFR induced and EDHF-mediated dilatation and hyperpolarization in CBA were also attenuated by using these inhibitors. The increased outward current density elicited by TFR in acutely isolated CBA smooth muscle cells was abolished by using TRAM-34 and Apamin. TFR upregulated the protein expression of TRPV4, SKca, and IKca that was also eliminated by these inhibitors. Laser scanning showed that the increased mean fluorescence intensity of Ca2+ by CIR was decreased by using TFR and that this effect was again eliminated by the above inhibitors.

CONCLUSIONS

We conclude that in the CBA of the CIR rats the protective effect of TFR on ischemic cerebrovascular injury may be related to the activation of the TRPV4 in both endothelium and smooth muscle by increasing its expression and activity. The activation of TRPV4 channel in the endothelium may be linked to the opening of endothelial IKca/SKca channels that induces EDHF-mediated relaxation and hyperpolarization in the smooth muscle cell. In addition, the activation of TRPV4 in the smooth muscle cell in CBA may be linked with the activation of BKCa channel through a TRPV4-dependent pathway, reduce Ca2+ concentration in the cell, and relaxes the vessel. These findings may form a new therapeutic target for protection of ischemic brain injury and facilitate the use of Chinese medicine in brain protection.

Effect of fetal anaemia on myocardial ischaemia-reperfusion injury and coronary vasoreactivity in adult sheep

AIMS

We investigated whether chronic fetal anaemia affects myocardial infarct in adulthood and elicits functional modifications in adult coronary vasoreactivity.

METHODS

Seven-month-old sheep that were made anaemic in utero and transfused to normal haematocrit before birth were studied. Infarct size was determined by tetrazolium after 1-h ischaemia (occlusion of the mid of left anterior descending artery) and 2-h reperfusion. The dose-response to vasoconstrictors and vasodilators was assessed in small resistance coronary arteries.

RESULTS

There were no significant differences between the animals previously subjected to in utero anaemia and the control animals regarding the percentage infarct size and the area-at-risk to the left ventricle. The ventricular function (dP/dt) was preserved. The percentage infarct size of the area-at-risk (70.7 +/- 3.5%) was larger than that in the controls (49.8 +/- 4.5%) (P = 0.006). The vascular responses were not altered. Endothelium-dependent relaxation to bradykinin (96.0 +/- 2.6% vs. 98.8 +/- 1.0%) was not affected by PGI(2) inhibitor (94.6 +/- 2.6% vs. 98.5 +/- 1.0%) but significantly reduced by the inhibition of nitric oxide (NO) in both anaemic (P < 0.05) and control (P < 0.001) groups with a significant right shift of EC(50) (P < 0.01). The non-NO-non-PGI(2)-mediated relaxation was slightly potentiated in anaemic animals.

CONCLUSIONS

Exposing fetal sheep to in utero anaemia in late gestation for 3 weeks may increase the susceptibility of adult hearts to ischaemia-reperfusion injury without major alterations in coronary vasomotor responsiveness. The impact of in utero anaemia at earlier period of pregnancy and on the earlier or later life of the adult is yet to be further investigated.

Proteomic study reveals plasma protein changes in congenital heart diseases

BACKGROUND

Congenital heart disease (CHD) is the most common birth defect in newborns. Plasma proteins may serve as indicators of disease and are a rich source for biomarker discovery, but little has been studied in CHD. We examined the hypothesis that plasma proteins may be altered and related to the pathologic changes of CHD.

METHODS

Differential protein analysis was performed in the plasma of patients with tetralogy of Fallot, isolated ventricular septal defect, and normal controls by using two-dimensional electrophoresis and mass spectrometry. Candidate proteins that might be related to disease processes were further confirmed by enzyme-linked immunosorbent assay in the new samples (n=40).

RESULTS

Identified were 18 differentially expressed protein spots and 10 corresponding proteins or polypeptides. Among those, 2 downregulated proteins, gelsolin, ficolin-3, with significant clinical relevance, were further analyzed for validation. The plasma levels of gelsolin (76.30±4.42 vs 131.80±23.46 μg/mL in control; p=0.025, n=40 in each group) and ficolin-3 (4.93±0.36 vs 10.58±1.58 μg/mL in control; p=0.001, n=40 in each group) in tetralogy patients were significantly lower than those in normal controls. The ficolin-3 plasma level was also lower in the patients with isolated VSD (5.55±0.34 vs 10.58±1.58 μg/mL in control μg/mL; p=0.003, n=40 in each group).

CONCLUSIONS

We used proteomic methods to demonstrate for the first time the plasma protein changes in CHD patients that may reveal the possible mechanisms for the prolonged bleeding time in tetralogy patients and the susceptibility to pulmonary infections in patients with CHDs. These findings have strong clinical implications.

Release of nitric oxide and endothelium-derived hyperpolarizing factor (EDHF) in porcine coronary arteries exposed to hyperkalemia: effect of nicorandil

BACKGROUND

Although the detrimental effect of hyperkalemia on coronary endothelium has been reported, there is no direct evidence regarding the effect of hyperkalemic exposure on nitric oxide (NO) release from the coronary endothelium. In addition, it is unclear whether nicorandil, a KATP channel opener, used as hyperpolarizing cardioplegia or added in hyperkalemic cardioplegic solution may protect endothelial function during cardiac surgery. The present study was designed to clarify NO release and the function of endothelium-derived hyperpolarizing factor (EDHF) in coronary circulation with respect to the effect of hyperkalemia and nicorandil.

METHODS

Nitric oxide was measured by using a NO-specific electrode, and EDHF-mediated relaxation was investigated in a myograph. Substance P- and calcium ionophore A23187-induced NO release was compared in porcine left circumflex coronary arteries before and after 1-hour exposure to 20 mM potassium (K+) at 37 degrees C. In coronary microarteries (diameter 200 to 450 microm), precontracted with U46619, in the presence of indomethacin (7 microM), NG-nitro-L-arginine (300 microM), and oxyhemoglobin (20 microM), EDHF-mediated relaxation was induced by bradykinin (-10 to -6.5 log M) after incubation with Krebs (control) or 20 mM K+ with or without 10 microM nicorandil at 37 degrees C for 1 hour.

RESULTS

Neither substance P (58.8 +/- 5.0 versus 66.2 +/- 7.2 nmol/L) nor A23187 (86.6 +/- 9.0 versus 82.4 +/- 9.2 nmol/L in control) induced NO release was altered by hyperkalemic exposure (p > 0.05). In contrast, EDHF-mediated relaxation was decreased from 84.2% +/- 3.8% to 42.3% +/- 6.0% (p < 0.001) that was partially restored by nicorandil (50.7% +/- 5.5%, p < 0.05).

CONCLUSIONS

Exposure to potassium at 20 mM does not affect NO release but impairs EDHF-mediated relaxation in coronary arteries. Supplementation of nicorandil in hyperkalemic cardioplegia may provide a protective effect on EDHF-related endothelial function.