Abstract-In 76 patients with heart failure (HF) (New York Heart Association [NYHA] classes I through IV) and in 15 control subjects, cardiac angiotensin II (Ang II) generation and its relationship with left ventricular function were investigated by measuring aorta-coronary sinus concentration gradients of endogenous angiotensins and in a part of patients by studying 125 I-labeled Ang I kinetics. Gene expression and cellular localization of the cardiac renin-angiotensin system components, the density of AT 1 and AT 2 on membranes and isolated myocytes, and the capacity of isolated myocytes for synthesizing the hypertrophying growth factors insulin-like growth factor-I (IGF-I) and endothelin (ET)-1 were also investigated on 22 HF explanted hearts (NYHA classes III and IV) and 7 nonfailing (NF) donor hearts. Ang II generation increased with progression of HF, and end-systolic wall stress was the only independent predictor of Ang II formation. Angiotensinogen and angiotensin-converting enzyme mRNA levels were elevated in HF hearts, whereas chymase levels were not, and mRNAs were almost exclusively expressed on nonmyocyte cells. Ang II was immunohistochemically detectable both on myocytes and interstitial cells. Binding studies showed that AT 1 density on failing myocytes did not differ from that of NF myocytes, with preserved AT 1 /AT 2 ratio. Conversely, AT 1 density was lower in failing membranes than in NF ones. Ang II induced IGF-I and ET-1 synthesis by isolated NF myocytes, whereas failing myocytes were unable to respond to Ang II stimulation. This study demonstrates that (1) the clinical course of HF is associated with progressive increase in cardiac Ang II formation, (2) AT 1 density does not change on failing myocytes, and (3)

Abstract-Physiological hypertrophy represents the adaptive changes of the heart required for supporting the increased hemodynamic load in regularly trained healthy subjects. Mechanisms responsible for the athlete's hypertrophy still remain unknown. In 15 trained competitive soccer players and in 15 healthy men not engaged in sporting activities (sedentary control subjects) of equivalent age, we investigated the relationship among cardiac growth factor formation, cardiac sympathetic activity, and left ventricular morphology and function. Cardiac formation of insulin-like growth factor (IGF)-I, endothelin (ET)-1, big ET-1, and angiotensin (Ang) II was investigated at rest by measuring artery-coronary sinus concentration gradients. Cardiac sympathetic activity was studied by [ 3 H]norepinephrine (NE) kinetics. Cardiac IGF-I, but not ET-1, big ET-1, and Ang II, formation was higher in athletes than in control subjects (PϽ0.01). NE levels in arterial and peripheral venous blood did not differ between groups. In contrast, coronary sinus NE concentration was higher in athletes than in control subjects (PϽ0.01). Cardiac, but not total systemic, NE spillover was also increased in athletes (PϽ0.01), whereas cardiac [ 3 H]NE reuptake and clearance were not different. Echocardiographic modifications indicated a volume overload-induced hypertrophy associated with increased myocardial contractility. Multivariate stepwise analysis selected left ventricular mass index as the most predictive independent variable for cardiac IGF-I formation and velocity of circumferential fiber shortening for cardiac NE spillover. In conclusion, increased cardiac IGF-I formation and enhanced sympathetic activity selectively confined to the heart appear to be responsible for the physiological hypertrophy in athletes performing predominantly isotonic exercise. Key Words: insulin-like growth factor-I Ⅲ norepinephrine Ⅲ sympathetic nervous system Ⅲ exercise Ⅲ hypertrophy, left ventricular T he heart sustains an increased hemodynamic load by adjusting its mass independently of whether the enhanced workload is due to physiological activity or to pathological alterations in the cardiovascular system. There is much evidence that the development of myocardial hypertrophy results from the interaction of mechanical forces (the increased workload) and cardiac growth factors. The hemodynamic overload leads to myocardial cellular stretch and strain that in turn induce gene expression of cardiac growth factors. 1,2 In regularly trained healthy subjects, both isotonic and isometric exercise cause cardiac changes resulting in modifications of the ventricular chambers and in a notable enhancement of heart performance. These modifications, called physiological hypertrophy or athlete's hypertrophy, are required for sustaining the tremendous increase in cardiac output during exercise. Cardiac growth factors involved in the development of physiological hypertrophy in humans are still unknown, and their knowledge might also be relevant for better understanding the mech...

Abstract-The aim of the present study was to investigate whether and which cardiac growth factors are involved in human hypertrophy, whether growth factor synthesis is influenced by overload type and/or by the adequacy of the hypertrophy, and the relationships between cardiac growth factor formation and ventricular function. Cardiac growth factor formation was assessed by measuring aorta-coronary sinus concentration gradient in patients with isolated aortic stenosis (nϭ26) or regurgitation (nϭ15) and controls (nϭ12). Gene expression and cellular localization was investigated in ventricular biopsies using reverse transcriptase-polymerase chain reaction and in situ hybridization. Cardiac hypertrophy with end-systolic wall stress Ͻ90 kdyne/cm 2 was associated with a selective increased formation of insulin-like growth factor (IGF)-I in aortic regurgitation and of IGF-I and endothelin (ET)-1 in aortic stenosis. mRNA levels for IGF-I and preproET-1 were elevated and mainly expressed in cardiomyocytes. At stepwise analysis, IGF-I formation was correlated to the mean velocity of circumferential fiber shortening (rϭ0.86, PϽ0.001) and ET-1 formation to relative wall thickness (rϭ0.82, PϽ0.001). When end-systolic wall stress was Ͼ90 kdyne/cm 2 , IGF-I and ET-1 synthesis by cardiomyocytes was no longer detectable, and only angiotensin (Ang) II was generated, regardless of the type of overload. The mRNA level for angiotensinogen was high, and the mRNA was exclusively expressed in the interstitial cells. Ang II formation was positively correlated to end-systolic stress (rϭ0.89, PϽ0.001) and end-diastolic stress (rϭ0.84, PϽ0.001). Multivariate stepwise analysis selected end-systolic stress as the most predictive variable and left ventricular end-diastolic pressure as the independent variable for Ang II formation (rϭ0.93, PϽ0.001). In conclusion, the present results indicate that the course of human left ventricular hypertrophy is characterized by the participation of different cardiac growth factors that are selectively related both to the type of hemodynamic overload and to ventricular function. (Circ Res. 1999;85:57-67.) Key Words: myocardial hypertrophy Ⅲ aortic valve disease Ⅲ endothelin-1 Ⅲ insulin-like growth factor-I Ⅲ angiotensin II

Abstract-Mechanical factors play a key role in activation of cardiac growth factor response in hemodynamic overload, and both cooperate in myocardial remodeling. The present study was performed to investigate whether a different growth factor response is activated in the right and left ventricles in aortocaval fistula and its effects on regional myocardial adaptation. Relations between regional growth factor expression (angiotensin II, insulin-like growth factor-I, and endothelin-1), myocyte shape changes, and collagen deposition were investigated at mRNA and peptide levels in adult pigs after the creation of an aortocaval fistula distal to the renal arteries (nϭ15) and in sham-operated animals (nϭ15). The role of angiotensin II was investigated by the administration of angiotensin-converting enzyme inhibitor or angiotensin II receptor antagonist. In the left ventricle, pure volume overload was accompanied by persistent increase of insulin-like growth factor-I mRNA expression, peptide concentration (2.2-fold versus sham at 3 months, PϽ0.05), and significant increase of myocyte length (ϩ29% at 3 months, PϽ0.05). Conversely, the mixed pressure-volume overload faced by the right ventricle resulted in significant regional overexpression of all growth factors investigated (angiotensin II, insulin-like growth factor-I, and endothelin-1), with corresponding increase of myocyte diameter and length and collagen deposition (ϩ117% at 3 months). Collagen accumulation in the right ventricle as well as the increase in right ventricular end-diastolic pressure at the 3-month observation were inhibited by angiotensin II antagonism. The left and right ventricles respond differently to aortocaval fistula, and local growth factor expression is closely related to the regional myocardial adaptation.

Abstract-Only scarce information is available on the activity and modifications of the cardiac endothelin (ET)-1 system in heart failure due to ischemic (ICM) or idiopathic dilated (DCM) cardiomyopathy. The activity of the ET-1 system was investigated by measuring cardiac ET-1 and big ET-1 formation and quantifying cardiac mRNA for prepro-ET-1 (ppET-1), ET-converting enzyme-1, and ET A and ET B receptors both in myocardium and in isolated myocytes using Northern blot, reverse transcription-polymerase chain reaction, and in situ hybridization in 22 patients with DCM and 20 with ICM who underwent cardiac transplantation and in 7 potential heart transplant donors (nonfailing hearts). Notwithstanding a similar increase of plasma ET-1 in the 2 groups, cardiac ET formation, mRNA levels for ppET-1, and ET A and ET B receptors were higher on both the myocardium and isolated myocytes from ICM than on those from DCM hearts (PϽ0.001 for all). ppET-1 and ET-converting enzyme-1 mRNAs were expressed on myocytes and endothelial and interstitial cells in ICM, whereas in DCM and nonfailing hearts they were mainly expressed on nonmyocyte cells. In both ICM and DCM, the ET A mRNA signal was expressed on both myocytes and nonmyocyte cells, whereas ET B mRNA was almost exclusively localized on nonmyocyte cells. ET A -and ET B -specific receptor binding was increased on both myocytes and cardiac membranes, showing a positive correlation with left ventricular ejection fraction in ICM (rϭ0.78 and 0.70) but not in DCM patients. The present results show that human ventricular myocytes express all of the components of the ET-1 system, which is selectively upregulated in ICM patients and appears to be functionally important in the maintenance of cardiac function. (Circ Res. 2000;86:377-385.)Key Words: endothelin Ⅲ heart failure Ⅲ myocytes Ⅲ receptors Ⅲ RNA E ndothelin (ET)-1 is a multifunctional peptide that exerts pleiotropic activities, including arterial and venous constriction, direct positive inotropic and chronotropic effects on isolated heart, and growth effects on vascular smooth muscle cells, fibroblasts, and isolated cardiomyocytes. 1 Prepro-ET-1 (ppET-1) mRNA is expressed by both rat and human cardiac myocytes and interstitial cells that synthesize and secrete mature ET-1. [2][3][4] The protease that catalyzes the conversion (ET-converting enzyme, ECE) from the 38-residue inactive intermediate big ET-1 to achieve ET-1 is expressed in the endocardium and myocardium. 5 The differing biological activities of ET-1 appear to be mediated through 2 receptor subtypes (ET A and ET B ), 6 which are both present in the human myocardium and that of other species. 7 Thus, a complete ET-1 system is represented in human myocardium.Cardiac ppET-1 mRNA expression and ET-1 synthesis have been found to be increased in experimental hypertrophy by pressure overload 8 -10 and in experimental models of congestive heart failure (CHF), [11][12][13] thus suggesting that the cardiac ET-1 system may be involved in cardiac diseases.There have been very f...

To investigate the time sequence of cardiac growth factor formation, echocardiographic and hemodynamic measurements were performed at scheduled times, and mRNAs for angiotensinogen, prepro-endothelin-1 (ppET-1), and insulin-like growth factor I (IGF-I) were quantified with RT-PCR and localized with in situ hybridization in pigs (fluothane anesthesia) by use of pressure or volume overload (aortic banding and aorta-cava fistula, respectively). Relative peptide formation was also measured by radioimmunoassay. In pressure overload, angiotensinogen and ppET-1 mRNA overexpression on myocytes (13 times vs. sham at 3 h and 112 times at 6 h, respectively) was followed by recovery (12 h) of initially decreased (0.5-6 h) myocardial contractility. In volume overload, contractility was not decreased, the angiotensinogen gene was slightly upregulated at 6 h (6.7 times), and ppET-1 was not overexpressed. IGF-I mRNA was overexpressed on myocytes (at 24 h) in both volume and pressure overload (14 times and 37 times, respectively). In the latter setting, a second ppET-1 overexpression was detectable on myocytes at 7 days. In conclusion, acute cardiac adaptation responses involve different growth factor activation over time in pressure versus volume overload; growth factors initially support myocardial contractility and thereafter induce myocardial hypertrophy.

This study of seven healthy young subjects was designed both to establish whether endothelin-1 (ET-1) is involved in the homeostasis of blood volume and to clarify the relationship between plasma and urinary ET-1. Acute volume expansion (+17%) caused increases in venous blood pressure (+4.4 mmHg) and the plasma concentration of ET-1 (+129%) and a decrease (-99%) in the urinary excretion of ET-1. Volume depletion (-8.5%) provoked an increase in the plasma concentration of ET-1 without altering the urinary excretion of ET-1. Passive elevation of an arm resulting in a local decrease of venous blood pressure (-17 mmHg) elicited an increase of the local formation of ET-1, with a 10-fold increase in the venous-arterial gradient compared with the opposite arm, which lay at the level of the heart. The increased local formation of ET-1 was blunted by volume expansion. The results indicate that 1) plasma ET-1 and urinary ET-1 represent two different endothelin-generating systems, both of which are involved in the regulation of blood volume, and 2) plasma ET-1 appears to be an important mechanism for the long-lasting adaptations of venous wall tension to changes in blood volume.

. Increased renal endothelin formation is associated with sodium retention and increased free water clearance. Am. J. Physiol. 275 (Heart Circ. Physiol. 44): H1070-H1077, 1998.-To investigate whether renal endothelin (ET)-1 participates in water and sodium handling, we investigated the influence of different sodium intakes on renal production of ET-1 in eight healthy subjects. The functional relationship with the reninangiotensin system was also studied. Renal ET-1 formation is affected by sodium intake, because 1 wk of high sodium decreased urinary ET-1 excretion (Ϫ34%, P Ͻ 0.05), whereas a low-sodium diet increased ET-1 excretion (66%, P Ͻ 0.05) and mRNA expression for preproendothelin-1 in epithelial cells of medullary collecting ducts and endothelial cells of the peritubular capillary network. Increased ET-1 renal synthesis was associated with sodium retention and increased free water clearance. Urinary ET-1 excretion changes from normal to low-sodium diet were negatively related to contemporary changes in sodium excretion (r ϭ 0.97, P Ͻ 0.05) and were positively correlated with free water clearance (r ϭ 0.97, P Ͻ 0.05). These correlations were maintained during angiotensin-converting enzyme inhibition, which only partially reduced ET-1 renal excretion. These results indicate that renal ET-1 production is indeed modulated by varying sodium intakes and may exert a role in sodium and water handling. sodium balance; renal function; urine; angiotensin II ABUNDANT EXPRESSION of endothelin (ET)-1 peptide and mRNA for its precursor, preproendothelin-1 (prepro-ET-1), have been found in the vascular endothelium of the renal vascular bed, including glomerular capillaries, arterioles, and peritubular capillaries (15,24). Subsequent studies have demonstrated that ET-1 is present in high concentrations in the inner medulla of the kidney (24), where ET-1 receptors are also located (5), and that ET-1 secretion is not limited to vascular endothelium, because primary epithelial cell cultures derived from the renal tubule secrete abundant amounts of ET-1 (10). ET-1 secretion in the renal medulla is highly compartmentalized in tubules with the following secretion hierarchy: inner medullary collecting ducts (IMCD) Ͼ medullary thick ascending limb Ͼ cortical collecting ducts Ͼ proximal tubule (11,29).The physiological activities of ET-1 on renal sodium and water handling still remain to be clarified (11). Convincing evidence exists that ET-1 may inhibit arginine vasopressin (AVP)-stimulated water reabsorption in the collecting ducts. Several studies have demonstrated that ET-1 binding to the ET B receptor subtype reduces Na ϩ -K ϩ -ATPase activity in the IMCD (34) and inhibits vasopressin-stimulated cAMP accumulation and water transport on isolated cortical collecting ducts from rats (23, 30). These and other studies (11,29) indicate that ET-1 might regulate water reabsorption independently of its effects on Na ϩ reabsorption or renal hemodynamics.Studies investigating the activity of ET-1 on sodium reabsorption have given confl...