AIM: To compare the protective effects of tongxinluo, a Chinese medicine, and carvedilol and valsartan on myocardium microvascular endothelial function and integrity after late reperfusion of acute myocardial infarction (AMI) in rabbits. METHODS: Forty-eight rabbits were randomly assigned to the following groups: (1) sham operated rabbits; (2) ischemia-reperfusion (I-R) controls; (3) tongxinluo (1.0 g?kg~ -1?d~ -1); (4) carvedilol (5 mg?kg~ -1?d~ -1); (5) valsartan (10 mg?kg~ -1?d~ -1) and (6) ticlopidine + aspirine (30 and 20 mg?kg~ -1?d~ -1, respectively) groups. After 3 d of drug treatment, the left coronary artery in the rabbit was ligated for 2 h and loosed subsequently for another 2 h. The serum levels of nitric oxide (NO_2~-/NO_3~-) and endothelin (ET) at baseline before AMI, 2 h after both AMI and reperfusion were examined. Also, the number of circulating endothelial cells (CEC), MI size and percentage myocardium focal bleeding incidence were determined 2 h after reperfusion. RESULTS: (1) The baseline level of NO_2~-/NO_3~- was significantly higher in tongxinluo group than that in other groups (all P

(0.05)). The sensitivity and the agreement rate were best at dose of Dob 10 ?g?kg~(-1)?min~(-1) with (86.5)% and (86.5)% (Kappa(0.71)), respectively. When Isoket combined with Dob 3,5 ?g?kg~(-1)?min~(-1), the sensitivities and the agreement rates were both significantly improved than either one used (both P

OBJECTIVETo 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.

METHODSForty 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).

CONCLUSIONThe 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.

Animals ; Drugs, Chinese Herbal ; therapeutic use ; Endothelin-1 ; biosynthesis ; blood ; genetics ; Female ; Male ; Myocardial Reperfusion Injury ; drug therapy ; metabolism ; Myocardium ; metabolism ; Phytotherapy ; RNA, Messenger ; biosynthesis ; genetics ; Random Allocation ; Swine ; Swine, Miniature

OBJECTIVESTo compare the effects of losartan, enalapril and their combination in the prevention of left ventricular remodeling (LVRM) after acute myocardial infarction (AMI) in the rat.

METHODSAMI model was induced in female SD rats by ligating left coronary artery. Forty-eight hours after the procedure, 83 surviving rats were randomized into one of the following 4 groups : 1) AMI control group (n = 19), 2) losartan group (n = 22, 3 mg x kg(-1) x d(-1)), 3) enalapril group (n = 20, 1 mg x kg(-1) x d(-1)), 4) losartan-enalapril combinative group (n = 22, 3 and 1 mg x kg(-1) x d(-1) respectively). 5) Sham-operated group (n = 10) and 6) normal rats group (n = 10) were selected randomly to serve as non-infarction controls. Losartan and enalapril were delivered by direct gastric gavage. After 4 weeks of medical therapy, hemodynamic studies were performed in each group, then the rat hearts were fixed with 10% formalin and pathologic analysis on them was performed. Complete experimental data was obtained in 56 rats, comprising 1) AMI controls (n = 11), 2) losartan group (n = 10), 3) enalapril group (n = 10), 4) the combination of losartan and enalapril group (n = 11), 5) sham-operated group (n = 6) and 6) normal controls (n = 8).

RESULTSThere were no significant differences among the 4 AMI groups in MI size (41.7% to approximately 43.4%, all P > 0.05). Compared with sham group, the left ventricular (LV) end diastolic pressure (LVEDP), volume (LVV), long and short axis length (L and D), as well as LV absolute and relative weight (LVAW and LVRW) in AMI group were all significantly increased (P < 0.05 to approximately 0.001); whereas the maximum left ventricular pressure rising and dropping rates (+/- dp/dt) and their corrected values by LV systolic pressure (+/- dp/dt/LVSP) were significantly reduced (all P < 0.001), indicating LVRM occurred and LV systolic and diastolic function impaired after AMI. Compared with AMI group, LVEDP, LVV, LVAW and LVRW were all significantly decreased (P < 0.05 to approximately 0.001); while +/- dp/dt/LVSP were significantly enhanced in all 3 treatment groups (P < 0.05 to approximately 0.001) except -dp/dt/LVSP in losartan group (P > 0.05). There were no significant differences in the above indices among the 3 treatment groups (all P > 0.05).

CONCLUSIONBoth losartan and enalapril can prevent from LVRM after AMI in the rat and improve LV function with equivalent effects. There seems no additive effect when the 2 drugs are used in combination.

Animals ; Antihypertensive Agents ; pharmacology ; Drug Synergism ; Enalapril ; pharmacology ; Female ; Losartan ; pharmacology ; Myocardial Infarction ; physiopathology ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Ventricular Function, Left ; drug effects ; Ventricular Remodeling ; drug effects

OBJECTIVETo compare the effects of high, middle and low doses of enalapril in preventing left ventricular remodeling (LVRM) after acute myocardial infarction (AMI) in rats, especially evaluating the efficacy of low dose enalapril.

METHODSAMI was induced by ligating the left coronary artery in 149 female SD rats. 48 hours after the procedure, the 97 surviving rats were randomized to one of the following four groups: (1) AMI controls (n = 24), (2) high-dose (10 mg x kg(-1) x d(-1), n = 25), (3) middle-dose (1 mg x kg(-1) x d(-1), n = 23), and (4) low-dose (0.1 mg x kg(-1) x d(-1), n = 25) enalapril groups. In addition, sham-operated (n = 13) and normal rats (n = 10) were randomly selected to serve as non-infarction controls. Enalapril was delivered by direct gastric gavage. After 4 weeks of therapy, hemodynamic studies were performed, then the rat hearts were fixed with 10% formalin and pathology analysis was performed. Exclusive of the dead rats and those with MI size < 35% or > 55%, complete experimental data were obtained from 67 rats, which were comprised of (1) AMI controls (n = 13), (2) high-dose enalapril (n = 13), (3) middle-dose enalapril (n = 12), (4) low-dose enalapril (n = 12), (5) sham-operated (n = 8) and (6) normal (n = 9) groups.

RESULTSThere were no significant differences among the four AMI groups in infarction size (all P > 0.05). Compared with the sham-operated group, the left ventricular (LV) end diastolic pressure (LVEDP), volume (LVV), absolute and relative weight (LVAW, LVRW) in AMI group were all significantly increased (all P < 0.001), while maximum LV pressure rising and dropping rates (+/- dp/dt) and their corrected values by LV systolic pressure (+/- dp/dt/LVSP) were all significantly reduced in the AMI control group (P < 0.01 - 0.001), indicating LVRM occurred and LV systolic and diastolic functions were impaired. Compared with the AMI group, LVEDP, LVV, LVAW and LVRW were all significantly decreased in the three enalapril groups (control P < 0.001), with the reduction of LVEDP, LVV and LVAW being more significant in high-dose than in low-dose enalapril groups (all P < 0.05), and the +/- dp/dt/LVSP were significantly increased only in the high and middle-dose enalapril groups (P < 0.01).

CONCLUSIONSHigh, middle and low doses of enalapril were all effective in preventing LVRM after AMI in the rat, with low dose enalapril being effective and high dose superior. As for LV functional improvement, only high and middle-dose enalapril were effective.

Angiotensin-Converting Enzyme Inhibitors ; administration & dosage ; pharmacology ; Animals ; Dose-Response Relationship, Drug ; Enalapril ; administration & dosage ; pharmacology ; Female ; Myocardial Infarction ; physiopathology ; Rats ; Rats, Sprague-Dawley ; Ventricular Remodeling ; drug effects