Genzou Takemura

Augmented expression of atrial natriuretic polypeptide gene in ventricle of human failing heart.

To elucidate the expression of the atrial natriuretic polypeptide (ANP) gene in the ventricle of the human failing heart, we have measured ANP and ANP messenger RNA (ANPmRNA) levels in left ventricular aneurysm obtained at operation, biopsy specimens of left ventricles from dilated cardiomyopathy (DCM) and autopsy samples of old myocardial infarction (OMI) and DCM hearts, and compared the levels with those in the normal ventricle. The ANP level (mean +/- SE) was 17.5 +/- 6.9 ng/g in the normal ventricle, and increased to 660.3 +/- 122.2 ng/g in the left ventricular aneurysm tissues and to 3,138.6 +/- 1,642.1 ng/g in the biopsy specimens of the DCM ventricle. These levels were approximately 40 and 200 times higher than in the normal ventricle. The increase of ANP levels was observed in both infarcted and noninfarcted regions of the OMI heart, and in the entire ventricle of the DCM heart. A significant positive correlation was found between the ANP level in aneurysm tissues and pulmonary capillary wedge pressure (r = 0.85). The ANPmRNA level in the left ventricular aneurysm showed about a 10-fold increase compared with that in the normal heart and reached 23% of that in the atrium of the same heart. A similar increase in the ANPmRNA level was observed in the entire ventricle of DCM. These data clearly indicate that the expression of the ANP gene in the ventricle is augmented in the failing heart in accordance with the severity of heart failure. In the atrium of the failing heart, ANP and ANPmRNA levels were only two times higher than those in the normal atrium. Thus, the augmentation in the expression of the ANP gene was more prominent in the ventricle than in the atrium. Taking tissue weight into account, the total content of ANPmRNA in the ventricle of the failing heart is much the same as that in the normal atrium. The ratio of the ANP level to the ANPmRNA level in the ventricle is much smaller than that in the atrium. These results suggest more rapid secretion of ANP after synthesis in the ventricle. These findings demonstrate that the expression of the ANP gene is augmented in the human ventricle of the failing heart and suggest that the ventricle becomes a substantial source of circulating ANP in congestive heart failure.

Expression and distribution of atrial natriuretic peptide in human hypertrophic ventricle of hypertensive hearts and hearts with hypertrophic cardiomyopathy.

To investigate the ventricular expression of atrial natriuretic peptide (ANP) in human hypertrophic hearts, we conducted an immunohistochemical study of 130 endomyocardial biopsy specimens obtained from the right side of the ventricular septum (RVB), left ventricular free wall (LVB), or both from a total of 80 patients: 44 patients with hypertrophic cardiomyopathy (HCM), 14 with apical hypertrophic cardiomyopathy (APH), 13 with hypertensive hearts (HHD), and nine without hypertrophy (controls). No patients had apparent congestive heart failure. ANP was not seen in ventricular myocytes in controls but was identified in biopsy specimens of hypertrophic hearts, and its distribution was characteristic in each hypertrophic group: 15 RVB (37%) and two LVB (7%) of the HCM group, one RVB (7%) and two LVB (18%) of the APH group, and zero RVB (0%/) and five LVB (46%) of the HHD group. Clinical data (including echocardiographic, hemodynamic, and angiographic data) were not directly related to ventricular ANP expression in HCM, APH, or HHD with one exception. In HHD patients, LVB specimens with ANP showed greater ventricular wall thickness than LVB specimens without ANP. According to histological data, however, the ANP-present RVB specimens of HCM or ANP-present LVB specimens of HHD had greater myocyte size than did the ANP-absent specimens. In addition, in HCM patients, the ANP-present RVB specimens showed more severe fibrosis and myofiber disarray than did the ANP-absent specimens. We conclude that a failing state and hemodynamic overload are not likely to be indispensable for ANP expression in human hypertrophic ventricles and that ventricular ANP expression occurs as a response to disease-specific changes: hemodynamic overload in HHD and histological changes such as myocardial fiber disarray, hypertrophy of myocytes, and fibrosis in HCM, which may reflect the characteristic distribution of intraventricular ANP.

Ventricular expression of atrial natriuretic polypeptide and its relations with hemodynamics and histology in dilated human hearts. Immunohistochemical study of the endomyocardial biopsy specimens.

To investigate the mechanism of expression of atrial natriuretic polypeptide (ANP) in human ventricles, we conducted an immunohistochemical study of ANP in biventricular endomyocardial biopsy specimens obtained from a total of 49 patients with cardiac dilatation due to dilated cardiomyopathy (21 patients), postmyocarditis (18 patients), or volume overload (five patients) and subjects with no dilatation as controls (five patients). Four-micron thick sections were stained by an indirect immunoperoxidase method using monoclonal antibody to alpha-human ANP as the primary antibody. The frequency of ANP-present myocytes was calculated in each specimen and compared with clinical, echocardiographic, hemodynamic, angiographic, and histologic parameters. ANP-present myocytes were noted in all of the 21 patients with dilated cardiomyopathy, in 11 of the 18 patients with postmyocarditis, in four of the five patients with volume overload, and in zero of the five controls. The mean percentage of ANP-present myocytes was significantly greater in the left-side specimens (35 +/- 37%) than in the right-side ones (2 +/- 4%). The percentage of ANP-present myocytes in the left-side specimens significantly correlated with peak systolic or end-diastolic wall stress (r = 0.67 and 0.58), left ventricular end-systolic or end-diastolic volume index (r = 0.75 and 0.69), or left ventricular end-diastolic pressure (r = 0.42) and inversely correlated with ejection fraction (r = -0.73), systolic left ventricular wall thickness (r = -0.58), or cardiac index (r = -0.30). Expression of ANP was rarely seen in the cases with normal wall stresses, normal ejection fraction, normal volume, or normal myocyte size. However, it was seen frequently even in hearts with normal levels of left ventricular end-diastolic pressure and cardiac index (compensated hearts). The percent of ANP-present myocytes in both sides significantly correlated with size of myocytes (r = 0.48 at right and r = 0.57 at left side) or degree of fibrosis (r = 0.45 at right and r = 0.48 at left side). These results suggest that ANP expression is augmented in the dilated ventricles regardless of the causes of dilatation and that the augmentation is a compensatory mechanism as prevention against decompensation responding to reduced contractility, excess of wall stresses, or both, concomitantly occurring with cardiac dilatation and myocardial hypertrophy.

Acceleration of cell necrosis following reperfusion after ischemia in the pig heart without collateral circulation

A study of whether reperfusion accelerates cell death was performed in 35 pig hearts without collateral circulation. In 15 animals, the distal one-third of the left anterior descending coronary artery was occluded for 1 hour followed by 1-, 3-, or 7-hour reperfusion in 5 animals each. As controls, 5 hearts each were examined after 1, 2, 4 and 8 hours of occlusion of the artery without reperfusion. Heart rate and aortic pressure before and during occlusion and reperfusion did not change in any group. The subepicardial and subendocardial regional blood flow decreased to almost zero in all hearts after occlusion (85 +/- 1 to 2 +/- 2) but recovered during reperfusion (65 +/- 15 ml/100 g/min). Specimens were histologically examined by an enzyme method using nitrotetrazolium blue, an immunohistochemical method using myoglobin antibody, by staining with hematoxylin-eosin and Massons trichrome. In the control hearts, clear demarcation of the infarct area was observed 4 hours after occlusion. However, in the reperfusion group, clear demarcation of the infarct was seen after 1-hour reperfusion, namely, 2 hours after the onset of infarct. Demarcation was seen not only in the tissue with contraction band necrosis, but also in the tissue with coagulation necrosis. Therefore, it is concluded that reperfusion accelerates cell death due to both contraction band necrosis and coagulation necrosis.

Response of large and small coronary arteries of pigs to intracoronary injection of acetylcholine: angiographic and histologic analysis

With coronary arteriography we examined the effect of acetylcholine (ACh) on large and small coronary arteries. ACh (12.5 to 200 micrograms) was injected into the right coronary arteries of 10 pigs during left ventricular pacing. The percentage of narrowing of the epicardial major coronary artery was used as an indicator of the constriction of the large coronary arteries, and the time required for the contrast medium to reach the posterior descending coronary artery from the ostium of the right coronary artery (blood-flow delay) was used as an indicator of the constriction of the same coronary arteries. A small dose of ACh (12.5 to 100 micrograms) induced mild narrowing (14 to 41%) of the epicardial major coronary artery and a marked blood-flow delay of over 7.0 sec (control: less than or equal to 1.8 sec) in all 10 pigs. A large dose of ACh (100 to 200 micrograms) caused over 75% narrowing of the epicardial major coronary artery and a marked blood-flow delay in 4 of the 10 pigs. When the marked blood-flow delay appeared, the perfused right ventricular myocardium became macroscopically anemic (ischemic). The constriction of large and small coronary arteries was not prevented by diphenhydramine (H1 blocker: 100 mg i.v.), but was prevented by pretreatment with atropine (1.0 mg i.v.). The intracoronary injection of histamine (1.5 mg) in 5 pigs constricted the epicardial major coronary artery over 75% in 2 pigs, 50 to 75% in 1 pig, and 25 to 50% in 2 pigs, but there was no evidence of blood-flow delay. Neither methoxamine nor norepinephrine caused any significant coronary artery narrowing. The histology of the large and small coronary arteries was examined quantitatively with an image analyzer. The coronary artery showed no intimal thickening, and the endothelium was intact on light microscopic examination. The % area of the smooth muscle layer (media) to the calculated total vascular area, and the ratio of the calculated medial thickness to the calculated inner radius (h/Ri) were 64 +/- 7% (mean +/- SD) and 0.69 +/- 0.16, respectively, in the small coronary arteries less than 100 microns in external diameter, 47 +/- 9% and 0.39 +/- 0.12 in the small coronary arteries 100 to 2000 microns in external diameter, and 34 +/- 4% and 0.24 +/- 0.03 in the large right coronary arteries over 2000 microns in external diameter; the % area of the media and the h/Ri showed a negative correlation with the size of the coronary arteries.(ABSTRACT TRUNCATED AT 400 WORDS)

Hypertrophy of surviving myocytes overlying the infarct in human old myocardial infarctions with abnormal Q waves.

The time course of hypertrophy of surviving myocytes overlying the infarct after the onset was examined and the hypertrophy was analyzed in relation to the transmural extent of infarct in 34 autopsied hearts with Q wave infarction. The 34 hearts were divided into 4 groups according to the length of time between the onset of infarction and death. This was less than 5 days in group 1 (n = 10), 20-30 days in group 2 (n = 7), 40-60 days in group 3 (n = 7), and 12-24 months in group 4 (n = 10). To clarify the regional hypertrophy of myocytes overlying the infarct, the size of the surviving myocytes in the outer third of the left ventricular wall in the 1-cm wide central zone of the infarct was compared with that of the myocytes in the outer third of the left ventricular wall without infarction (control wall) in the same heart. To exclude factors which stimulate the hypertrophy of the whole left ventricle, the ratio of the monocyte diameter in the infarcted wall to that in the control wall was examined. It was 1.0 +/- 0.0 (mean +/- SD) in group 1, 1.0 +/- 0.1 in group 2, 1.2 +/- 0.1 in group 3, and 1.3 +/- 0.1 in group 4. The ratio was significantly higher in group 3 than in group 1 and 2, and was highest in group 4. In group 4, the corrected percentage transmural extent of infarct indicating the original transmural extent of infarct at the acute stage was 63 + 8%, and this transmural extent correlated positively with the ratio of myocyte diameter.(ABSTRACT TRUNCATED AT 250 WORDS)

Failure to reduce infarct size by intracoronary infusion of recombinant human superoxide dismutase at reperfusion in the porcine heart: Immunohistochemical and histological analysis

Failure to Reduce Infarct Size by Intracoronary Infusion of Recombinant Human Superoxide Dismutase at Reperfusion in the Porcine Heart: Immunohistochemical and Histological Analysis. Journal of Molecular and Cellular Cardiology (1991) 23, 1287-1296. We quantitatively determined the extent of infarction and contraction band necrosis in porcine hearts, and analyzed the distribution of administered recombinant human superoxide dismutase (h-SOD) in the myocardium using a polyclonal antibody to h-SOD. After 1 hour of occlusion, h-SOD was infused for the first 30 min of reperfusion in SOD group, while pigs received only arterial blood in control group. The extent of infarction or contraction band necrosis was not significantly different between SOD group and control group. Positive staining by polyclonal antibody to h-SOD was detected only in the infarcted area in SOD group. Thus, h-SOD only entered irreversibly damaged myocytes and neither diminished reperfusion injury nor reduced infarct size in pigs.

Influence of propranolol on high energy phosphate and tissue acidosis in regional ischemic myocardium of pigs: assessment with arterial pressure and respiration gated in vivo 31-phosphorus magnetic resonance spectroscopy

In an attempt to define the metabolic abnormalities of the ischemic myocardium, the changes in high energy phosphates, inorganic phosphate and intracellular pH were serially and quantitatively evaluated in ischemic porcine hearts having no collateral circulation, using arterial pressure and respiration gated in vivo 31P magnetic resonance spectroscopy. The protocol was also modified for propranolol pretreatment (0.6 mg/kg intravenously) to define its effect on the metabolism of ischemic myocardium. In the non-treated group, creatine phosphate was rapidly depleted by 10 minutes after ischemia; by 40 minutes, ATP and intracellular pH gradually decreased to 10 +/- 11% of control and to 5.90 +/- 0.26, respectively, and inorganic phosphate rose to 303 +/- 43% of control. In the propranolol treated group, the concentrations of creatine phosphate and ATP were higher, and those of inorganic phosphate and tissue pH were similar compared with controls during 40 minutes of ischemia. This suggests that the beneficial effect of propranolol on the ischemic myocardium is due to the preservation of ATP, an essential energy resource for numerous enzymatic reactions in viable myocardium.

Relationship between ventricular expression of atrial natriuretic polypeptide gene and hemodynamic parameter in old myocardial infarction.

&NA; Using Northern blot analysis and radioimmunoassay, we measured atrial natriuretic polypeptide (ANP) messenger RNA and ANP levels in the ventricle in patients with old myocardial infarction and investigated the relationship between ventricular ANP synthesis and hemodynamic parameters. Levels of ANP messenger RNA and ANP were markedly increased in the left ventricular aneurysm, and a positive correlation was observed between the ANP level in the left ventricular aneurysm and pulmonary capillary wedge pressure (r = 0.85, p < 0.05). These findings indicate that ANP synthesis in the ventricle is increased in accordance with the severity of congestive heart failure.