Tongxinluo reduces myocardial no-reflow and ischemia-reperfusion injury by stimulating the phosphorylation of eNOS via the PKA pathway.

The objective of the present study was to investigate whether pretreatment with single low loading dose of tongxinluo (TXL), a traditional Chinese medicine, 1 h before myocardial ischemia could attenuate no-reflow and ischemia-reperfusion injury by regulating endothelial nitric oxide synthase (eNOS) via the PKA pathway. In a 90-min ischemia and 3-h reperfusion model, minipigs were randomly assigned to the following groups: sham, control, TXL (0.05 g/kg, gavaged 1 h before ischemia), TXL + H-89 (a PKA inhibitor, intravenously infused at a dose of 1.0 µg·kg(-1)·min(-1) 30 min before ischemia), and TXL + N(ω)-nitro-L-arginine (L-NNA; an eNOS inhibitor, intravenously administered at a dose of 10 mg/kg 30 min before ischemia). TXL decreased creatine kinase (CK) activity (P < 0.05) and reduced the no-reflow area from 48.6% to 9.5% and infarct size from 78.5% to 59.2% (P < 0.05), whereas these effects of TXL were partially abolished by H-89 and completely reversed by L-NNA. TXL elevated PKA activity and the expression of PKA, Thr(198) phosphorylated PKA, Ser(1179) phosphorylated eNOS, and Ser(635) phosphorylated eNOS in the ischemic myocardium. H-89 repressed the TXL-induced enhancement of PKA activity and phosphorylation of eNOS at Ser(635), and L-NNA counteracted the phosphorylation of eNOS at Ser(1179) and Ser(635) without an apparent influence on PKA activity. In conclusion, pretreatment with a single low loading dose of TXL 1 h before ischemia reduces myocardial no-reflow and ischemia-reperfusion injury by upregulating the phosphorylation of eNOS at Ser(1179) and Ser(635), and this effect is partially mediated by the PKA pathway.

Pretreatment with Tongxinluo protects porcine myocardium from ischaemia/reperfusion injury through a nitric oxide related mechanism.

BACKGROUND: The traditional Chinese medicine Tongxinluo can protect myocardium against ischaemia/reperfusion injury, but the mechanism of its action is not well documented. We examined the involvement of nitric oxide in the protective role of Tongxinluo. METHODS: Miniswine were randomized to four groups of seven: sham, control, Tongxinluo and Tongxinluo coadministration with a nitric oxide synthase inhibitor N(omega)-nitro-L-arginine (L-NNA, 10 mg/kg i.v.). Three hours after administration of Tongxinluo, the animals were anaesthetised and the left anterior descending coronary artery ligated and maintained in situ for 90 minutes followed by 3 hours of reperfusion before death. Area of no reflow and necrosis and risk region were determined pathologically by planimetry. The degree of neutrophil accumulation in myocardium was obtained by measuring myeloperoxidase activity and histological analysis. Myocardial endothelial nitric oxide synthase activity and vascular endothelial cadherin content were measured by colorimetric method and immunoblotting analysis respectively. RESULTS: Tongxinluo significantly increased the local blood flow and limited the infarct and size of no reflow. Tongxinluo also attenuated myeloperoxidase activity and neutrophil accumulation in histological sections and maintained the level of vascular endothelial cadherin and endothelial nitric oxide synthase activity in the reflow region when compared with control group. The protection of Tongxinluo was counteracted by coadministration with L-NNA. CONCLUSIONS: Tongxinluo may limit myocardial ischaemia and protect the heart against reperfusion injury. Tongxinluo regulates synthesis of nitric oxide by altering activity of endothelial nitric oxide synthase.

[Effects of tongxinluo on mini-swine vascular endothelial integrity and myocardial no-reflow in early reperfusion of acute myocardial infarction].

OBJECTIVE: To assess the effects of tongxinluo on vascular endothelial integrity and myocardial no-reflow in early reperfusion of acute myocardial infarction. METHODS: Forty mini-swines were divided into five groups randomly, sham group, control group, low dose (0.1 g/kg), medium dose (0.2 g/kg) and high dose (0.4 g/kg) groups of Tongxinluo. It was administered at 2 hours pre-reperfusion. Animals except in sham group were subjected to 1.5 hour of coronary occlusion followed by 3 hours of reperfusion. Content of VE-cadherin, beta-catenin, matrix metalloproteinase (MMP)-2 and 9 in myocardium were evaluated; no-reflow area was examined with myocardial contrast echocardiography (MCE) at 1.5 hour of AMI and 3 hours of reperfusion. RESULTS: (1) Compared with that of normal myocardium, content of VE-cadherin and beta-catenin decreased in reperfusion and no-reflow myocardium while MMP-2 and 9 increased significantly (all P < 0.05); (2) Compared with that of control group, a high dose of Tongxinluo could increase significantly the content of VE-cadherin in both reperfusion and no-reflow myocardium, (22.2 +/- 3.2)% vs (32.0 +/- 3.9)% and (14.5 +/- 2.8)% vs (28.3 +/- 2.2)% respectively, beta-catenin, (20.5 +/- 3.5)% vs (27.3 +/- 2.9)% and (13.3 +/- 2.1)% vs (20.6 +/- 2.4)%, while reduce MMP-2, (48.3 +/- 4.1)% vs (29.4 +/- 3.5)% and (57.3 +/- 4.3)% vs (38.2 +/- 4.0)% respectively, MMP-9, (55.6 +/- 4.0)% vs (34.3 +/- 3.5)% and (62.4 +/- 4.8)% vs (44.4 +/- 4.1)%, all P < 0.05; (3) Compared with that of control group, a high dose of Tongxinluo could reduce significantly both no-reflow area, (6.6 +/- 1.7) cm2 vs (4.7 +/- 1.5) cm2, P < 0.05, and percentage (90.8 +/- 3.8)% vs (71.4 +/- 4.1)%, P < 0.05, at 3 hours of reperfusion. CONCLUSION: A high dose of tongxinluo could effectively maintain the integrity of vascular endothelium and attenuate no-reflow area in early reperfusion of acute myocardial infarction.

[Effect of tongxinluo on endothelin-1 in the mini-swine model of acute myocardial infarction and reperfusion].

OBJECTIVE: To evaluate the change of endothelin-1 (ET-1) in the mini-swine model of acute myocardial infarction (AMI) and reperfusion and the effect of Tongxinluo (TXL) on it, and to explore the possible mechanism of no-reflow. METHODS: Forty mini-swines were randomized into 5 groups: the model group, the small,middle and large dose of TXL groups and the sham-operated group, 8 in each group. The AMI reperfusion model was established by coronary ligation for 3 hrs followed with relaxation for 1 hr. Plasma ET-1 content before and after AMI, and after reperfusion was determined respectively by radioimmunoassay. The ET-1 mRNA expression in myocardial tissue of normal, ischemic and no-reflow area were respectively quantified by reverse transcription-polymerase chain reaction. RESULTS: (1) Compared with before AMI, levels of plasma ET-1 at the time points of 5 min and 3 hrs after AMI, 5 min and 1 hrs after reperfusion in the model group were significantly raised, showing an increasing tendency (all P < 0.01). But the increment in the middle and large dose of TXL groups were all lower than that in the model group (P < 0.05). (2) In the model and the TXL groups, levels of ET-1 in myocardial tissue of ischemic and no-reflow area were significantly higher than those in the normal area, and the increment in no-reflow area was higher than that in ischemic area (all P < 0.01). Compared with the model group, significant lowering of ET-1 in ischemic area was only shown in the middle and large dose of TXL groups (P < 0.01). (3) In the model and the TXL groups, ET-1 mRNA expression in ischemic area was significantly higher (all P < 0.01), while it in no-reflow area was significantly lower than that in the normal area respectively (all P < 0.01). The raised ET-1 mRNA expression in the middle and large dose TXL groups was significantly lowered when compared with that in the model group (P < 0.01). CONCLUSION: The endothelium injury might be one of the important mechanisms for no-reflow phenomenon. TXL might reduce the no-reflow by protecting endothelium cells. was significantly higher (all P < 0.01), while it in no-reflow area was significantly lower than that in the normal area respectively (all P < 0.01). The raised ET-1 mRNA expression in the middle and large dose TXL groups was significantly lowered when compared with that in the model group (P < 0.01). Conclusion The endothelium injury might be one of the important mechanisms for no-reflow phenomenon. TXL might reduce the no-reflow by protecting endothelium cells.

[Beneficial effects of Tong-xin-luo (herb) on myocardial no-reflow after acute myocardial infarction and reperfusion: experiment of mini-swine model].

OBJECTIVE: To evaluate the beneficial effects of Tong-xin-luo on myocardial no-reflow after acute myocardial infarction (AMI) and reperfusion. METHODS: Forty mini-swine were randomized into 5 equal groups: control group, low-dose group (pretreated with Tong-xin-luo 0.05 g.kg(-1).d(-1) for 3 days), medium-dose group (pretreated with Tong-xin-luo 0.2 g .kg(-1).d(-1) for 3 days), high-dose group (pretreated with Tong-xin-luo 0.5 g.kg(-1).d(-1) for 3 days), and sham-operation group. The swine in the former four groups were subjected to 3 hours of coronary occlusion followed by 60 minutes of reperfusion. Left ventricle systolic pressure (LVSP), left ventricle end diastolic pressure (LVEDP), rate of maximum pressure change in left ventricle (+/- dp/dt(max)), cardiac output (CO), and heart rate (HR) were measured 5 min before AMI in all groups and 180 min after AMI and 60 min after reperfusion in the groups 1-4. Coronary blood volume (CBV) was recorded 5 min before AMI in all groups and immediately and 60 min after reperfusion in the group 1-4. Myocardial contrast echography (MCE) was used before AMI, 3 h after AMI, and 60 min after reperfusion in the group 1-4 so as to calculate the left ventricle wall area (LVWA), ligation area (LS), and %LA. Sixty minutes after reperfusion thioflavin-S was injected into the left ventricle to dye the reperfusion area, then the descending anterior branch was re-ligated at the original site and Evan's blue was injected into the left ventricle to dye the area outside the reperfusion area blue. The heart was taken out immediately to undergo pathological examination and calculation of LVWA, LS, area of no-reflow (SNR), LA, ANR. necrosis area (NS), and NA. RESULTS: (1) In the control group, systolic and diastolic blood pressures (SBP and DBP), LVSP, +/- dp/dt(max), and CO significantly decreased (P < 0.05 or P < 0.01), while LVEDP significantly increased (P < 0.01) 3 hour after AMI, and then LVSP was significantly recovered while +/- dp/dt(max) further significantly decreased (both P < 0.05) 60 minutes after reperfusion. In the 3 Tongxinluo groups, the changes of LVSP, +/- dp/dt(max), CO and LVEDP were the same as those in the control group 3 hours after AMI, and 60 minutes after reperfusion, +/- dp/dt(max), CO and LVEDP were recovered significantly in the high-dose group to degrees better than those in the control group (all P < 0.05). (2) In the control group, the LS values measured by MCE in vivo and by pathological evaluation were similar (P > 0.05), and the SNR was 78.5% by MCE in vivo and was 82.3% by pathological evaluation with the final NS reaching 98.5% of LS. There was no significant difference in LS by both MCE and pathological evaluation between the Tongxinluo groups and control group, though the values of SNR by both methods in the medium and high-dose groups were 41.1% and 42.4% and 24.1% and 25.0% respectively, all significantly lower than those in the control group and low-dose group (P < 0.05 or P < 0.01) with the values in the high-dose group being significantly lower than those in the median-dose group (P < 0.05 and P < 0.01). The final NS of pathological evaluation was also significantly decreased to 90.2%and 81.2% of LS (P < 0.05). In the control group, CBV was significantly decreased to 45.8% and 50.6% of the baseline value immediately at the beginning of reperfusion and 60 minutes after reperfusion (both P < 0.01). In the high-dose group, CBV was also significantly decreased to 76% and 73.5% of the baseline value immediately at the beginning of reperfusion and 60 minutes after reperfusion (both P < 0.05), however, both significantly higher than those in the control group (both P < 0.01). CONCLUSION: Tongxinluo is effective in preventing myocardial no-reflow, improving left ventricular function and reducing infarct area during AMI and reperfusion.