Aging might increase myocardial ischemia / reperfusion-induced apoptosis in humans and rats

Abstract

Previous studies indicated aging results in the significant cardiac function decreasing and myocardial apoptosis increasing in normal humans or rats. Additionally, animal experiments demonstrated aging increased myocardial ischemia / reperfusion (MI/R)-induced apoptosis. However, whether more myocardial apoptosis happen in the old acute myocardial infarction (AMI) patients is unclear. Reperfusion injury-induced apoptosis is an important cause of heart failure. This study determined the effect of aging upon myocardial apoptosis and cardiac function in patients suffering AMI. All enrolled AMI patients received percutaneous coronary intervention therapy. Volunteers and AMI patients were assigned to four groups: adult (age <65, n = 24) volunteers, elderly (age ≥65, n = 21) volunteers, adult (age <65, n = 29) AMI patients, and elderly (age ≥65, n = 36) AMI patients. Blood samples were obtained from all study participants. Plasma apoptotic markers (soluble form of Fas, tumor necrosis factor alpha, and interleukin 6) levels were determined. Cardiac function was evaluated with echocardiogram and Killip class. Due to lack of a direct apoptotic assay method in live human subjects, an additional animal experiment was performed. Both young (2 months) and old (24 months) rats were subjected to 30-min myocardial ischemia and 3 (for TUNEL/caspase activity apoptotic assay) or 24-h (for cardiac function determination) reperfusion. Compared to adult patients, the elderly patients manifested decreased cardiac function and increased plasma apoptotic marker levels significantly. The animal experiment results (cardiac function and plasma apoptotic markers assays) were consistent with the human result data. Animal TUNEL staining and caspase activity measurement revealed a higher myocardial apoptotic ratio in the older rat group. Aging exacerbated MI/R injury in humans and rats. Differential myocardial apoptosis may play a vital role in mediating the observed effects.

Fig. 1

The grouping of clinical trial

Fig. 2

Aging associated with decreased cardiac function in healthy volunteers and AMI patients. a Left ventricular ejection fraction (LVEF), b left ventricular fractional shortening (LVFS), and c E/A value depict volunteer data. d LVEF, e LVFS, f E/A value, and g Killip class depict AMI data. Adult indicates adult group; elderly indicates the elderly group. Total for the following groups: adult volunteers—24, old volunteers—21, adult patients—29, and old patients—36. Data expressed as mean ± SD. *P < 0.05, **P < 0.01 vs. adult group

Fig. 3

Aging associated with decreased cardiac function in rats after 24-h reperfusion. a Effects of aging upon left ventricular systolic pressure (LVSP). b Left ventricular end diastolic pressure (LVDEP). c, d Rate of rise of left ventricular pressure (±dp/dt). Young indicates young sham group; old indicates old sham group; young MI indicates young I/R group; old MI indicates old I/R group. n = 8 in each group. Data expressed as mean ± SD. *P < 0.05, **P < 0.01 vs. adult group, ^##P<0.01 vs. young MI group

Fig. 4

Effects of aging upon MI/R injury in humans and rats. Top Representative photomicrographs of Evans blue–triphenyltetrazolium chloride (TTC) staining in sectioned rat heart tissue. Bottoma Bar chart of myocardial infarct size (IS) expressed as percentage of area at risk (AAR) of the ischemic-reperfused myocardium. b Plasma cTnI concentration in different rat groups. c Plasma cTnI concentration in AMI patients 24 h, 3 days, and 5 days after PCI. Data were expressed as mean ± SD. *P < 0.05, **P < 0.01 vs. young/adult group, ^##P<0.01 vs. young MI group

Fig. 5

Effects of aging upon I/R-induced myocardial apoptosis in rats. Top Representative photomicrographs of TUNEL staining in all four groups. Total nuclei were labeled with DAPI (blue) and apoptotic nuclei appear green by TUNEL staining. a TUNEL-positive myocytes. b Caspase-3 activity. n = 8 in each group. Data expressed as mean ± SD. *P < 0.05, **P < 0.01 vs. young group, ^##P<0.01 vs. young MI group

Fig. 6

Aging increased plasma apoptotic markers (sFas, TNF-α, and IL-6) in patients 24 h, 3 days, and 5 days after PCI. Patient plasma a sFas, b TNF-α, and c IL-6 concentrations. Total for the following groups: adult volunteers—24, elderly volunteers—21, adult patients—29, and elderly patients—36. Data expressed as mean ± SD. *P < 0.05, **P < 0.01 vs. adult group

Fig. 7

Aging increased plasma apoptotic markers (sFas, TNF-α, and IL-6) in rats after 24 h I/R. Rat plasma a sFas, b TNF-α, and c IL-6 concentrations. n = 8 in each group. Data expressed as mean ± SD. *P < 0.05, **P < 0.01 vs. young group, ^##P<0.01 vs. young MI group