Ismayil Ahmet

Gene transfer of hepatocyte growth factor improves angiogenesis and function of chronic ischemic myocardium in canine heart

BACKGROUND Hepatocyte growth factor (HGF) induces angiogenesis in myocardium. In the present study, its effects in chronic ischemic myocardium were tested. METHODS Four weeks after left anterior descending coronary artery ligation in canine hearts, HVJ-liposome containing either human HGF gene (160 microg; HGF group, n = 7) or nothing (control group, n = 6) was directly injected into ischemic myocardium. Four weeks after gene transfection, the thickness fraction (TF), an index of regional myocardial contractility (assessed by epicardial pulse-Doppler crystals), the myocardial perfusion flow (assessed by color microspheres), and the capillary density (assessed by immunostaining of vessels) were evaluated in ischemic myocardium. RESULTS Thickness fraction (percent of nonischemic myocardium) was significantly improved in the HGF group (80 +/- 15 from 52 +/- 16 of pregene; p < 0.05) whereas it was not changed in the control group (52 +/- 10 from 50 +/- 8 of pregene). The perfusion flow (% of nonischemic myocardium) was significantly improved in the HGF group (98 +/- 17 from 51 +/- 14 of pregene; p < 0.05) while it was not changed in the Control group (58 +/- 13 from 62 +/- 18 of pregene). The capillary density was significantly higher in the HGF group (894 +/- 211/mm2; p < 0.05) than that in the control group (511 +/- 127/mm2). CONCLUSIONS Gene transfection of HGF improved angiogenesis, thereby improved regional myocardial function and perfusion in chronic ischemic myocardium. It indicates a potent therapeutic value of HGF gene transfection for chronic ischemic heart diseases such as myocardial infarction.

Diadenosine tetraphosphate (AP4A) mimics cardioprotective effect of ischemic preconditioning in the rat heart: contribution of KATP channel and PKC

Abstract Diadenosine tetraphosphate (AP4A) administration is reported to mimic the effect of ischemic preconditioning (PC) via purine 2y receptors (P2yR) and adenosine receptors. This study was designed to test the contributions of the ATP-sensitive potassium channel (KATP channel) and protein kinase C (PKC), two of the main regulator in PC, to the effect of AP4A. Isolated buffer-perfused rat hearts were subjected to 20 min of global ischemia (37 °C) and 20 min of reperfusion. Three cycles of 1-min ischemia and 3-min reperfusion induced PC. Chemicals were administrated for 2 min before 20 min of ischemia. AP4A (10 μM) administration was as effective as PC in improving the recovery of post-ischemic contractile function and reducing creatine kinase leakage after reperfusion, whereas adenosine (10 and 100 μM) have not effect. AP4A had not effect on reperfusion-induced arrhythmia, whereas PC significantly prevented it. These effects of AP4A and PC were reversed by co-administration of glibenclimade (KATP channel blocker, 100 μM) and GF109203X (PKC inhibitor, 10 μM); the effects of AP4A but not PC were reversed by co-administration of reactive blue (P2yR antagonist, 13 nM). AP4A appears to activate the KATP channel and PKC via P2yR mimic the effects of PC in part. The role of P2yR indicated that trigger mechanism of the effect of PC and AP4A administration might differ in rat hearts.

Therapeutic angiogenesis induced by injecting hepatocyte growth factor in ischemic canine hearts.

PurposeTherapeutic angiogenesis, induced by the direct injection of angiogenic growth factors or by transmyocardial laser revascularization (TMLR), has shown great potential as a new therapeutic strategy for end-stage coronary artery disease. However, no significant differences in angiogenic effects of TMLR and vascular endothelial growth factor (VEGF) have been reported. We compared the effects of the intramyocardial injection of hepatocyte growth factor (HGF), a novel angiogenic factor, with those of TMLR, by evaluating the improvement in regional blood flow and regional function in a canine heart model of chronic ischemia.MethodsTo create a model of chronic ischemia, we ligated the left anterior descending artery (LAD) in 15 beagles. We divided the dogs into three groups according to the treatment given 1 month after ligation. Four dogs were given an intracardial injection of human recombinant HGF (H group), six dogs were given TMLR (T group), and five dogs were used as a control (C group). We compared the degree of improvement in regional blood flow and regional function 1 month after the treatment.ResultsThe regional myocardial blood flow and function were significantly better in the H group than in the T or C groups (P < 0.05). Histologically, there were significantly more von Willebrand factor-positive cells in the LAD region in the H group than in the T or C groups.ConclusionThe intramural injection of recombinant human HGF resulted in therapeutic angiogenesis with an intrinsic contractile state, and it may have greater advantages than TMLR for the treatment of chronic ischemic heart disease.

Myocardial protection using diadenosine tetraphosphate with pharmacological preconditioning.

BACKGROUND We have reported a similar cardioprotective effect and mechanism of diadenosine tetraphosphate (AP4A) and ischemic preconditioning in rat hearts. In this study, the applicability of AP4A administration to cardiac surgery was tested by using a canine cardiopulmonary bypass model. METHODS Hearts underwent 60 minutes of cardioplegic arrest (34 degrees C) by a single dose of cardioplegia. Cardioplegia contained either AP4A (40 micromol/L; n = 6) or saline (n = 6). Beagles were weaned from cardiopulmonary bypass 30 minutes after reperfusion, and left ventricular function was evaluated after another 30 minutes by using the cardiac loop analysis system. RESULTS Administration of AP4A significantly improved the postischemic recovery of cardiac function and reduced the leakage of serum creatine kinase compared with saline. Systemic vascular resistance, mean aortic blood pressure, and the electrocardiographic indices were not significantly altered by AP4A administration. CONCLUSIONS Administration of AP4A was cardioprotective without apparent adverse effects. Because the cardioprotective mechanism may be similar to that of ischemic preconditioning, the addition of AP4A into cardioplegia may be a novel safe method for clinical application of preconditioning cardioprotection.

The Effects of a New Ultra-Short-Acting β-Adrenergic Blocker, ONO-1101, on Cardiac Function During and After Cardiopulmonary Bypass

The administration of an ultra-short-acting β-adrenergic antagonist, esmolol, has been introduced as a novel method for beating-heart surgery. In the present study, a new ultra-short-acting β-blocker, ONO-1101, was administered during cardiopulmonary bypass (CPB) to investigate its effects on cardiac function and hemodynamics. Nine adult mongrel dogs underwent 60 min of CPB during which they were given either ONO-1101 (ONO group;n=4) or saline (control group;n=5). In the ONO group, the hearts became flaccid enough for surgery to be performed without cardiac standstill within 10min after the commencement of ONO-1101 with significant decreases in the heart rate, the preload recruitable stroke work (PRSW), and the slope of the endsystolic left ventricular pressure-volume relationship (Emax). The mean arterial pressure and systemic vascular resistance also decreased, but were maintained above 50 mmHg during CPB without catecholamine. These indices increased to the control group level 20 min after the discontinuation of ONO-1101. The serum concentration of ONO-1101 decreased from the maximum level of 121±15 μg/ml soon after infusion to 11 ±5 μg/ml within 30 min after discontinuation. These data suggest that ONO-1101 may be useful to enable beating-heart surgery to be performed without aortic cross-clamp as an ultra-short-acting β-adrenergic blocker.

Cardioprotective effect of diadenosine tetraphosphate (AP4A) cardioplegia in isolated rat hearts

Abstract Preischemic administration of diadenosine tetraphosphate (AP4A) has been shown to be cardioprotective. We evaluated the protective effect of AP4A when used as a cardioplegic adjuvant and tested contributions of the ATP-sensitive potassium channel (KATP channel), adenosine receptor (AR), and purine 2y receptor (P2yR) to the effect of AP4A. Isolated buffer-perfused rat hearts were subjected to 23 min of ischemia (37°C) followed by 20 min of reperfusion. Cardioplegia solution (St. Thomas Hospital solution) was infused during the first 3 min of ischemia. AP4A (10 μM) or AP4A with glibenclamide (KATP channel blocker, 100 μM), 8-SPT (AR antagonist, 300 μM) or reactive blue (P2yR antagonist, 13 nM) were added to the cardioplegia solution. Compared with the cardioplegia solution alone, administration of AP4A with the solution significantly increased the recovery of rate-pressure production (75% ± 11% vs 58% ± 10%; P < 0.05) and dp/dt at the end of reperfusion, and reduced the leakage of creatine kinase (3.2 ± 3.7 vs 13.2 ± 10.1 IU/g; P < 0.05) during reperfusion. This effect was reversed by coadministration of glibenclamide or reactive blue but not 8-SPT. The addition of AP4A into the cardioplegia solution led to an added cardioprotective effect, either by opening the KATP channel or by activating P2yR.