ACE and angiotensinogen gene genotypes and left ventricular mass in athletes

Cardiodiagnostic sex-specific differences of the female athlete in sports cardiology

The cardiovascular care of highly active individuals and competitive athletes has developed into an important focus within the field of sports medicine. An evolving understanding of exercise-induced cardiovascular remodeling in athletes has led to a more robust characterization of physiologic adaptation versus pathological dysfunction, but this distinction is often challenging due to diagnostic commonalities. Current data reflects sporting-focused analyses of mainly male athletes, which may not be easily applicable to the female athletic heart. Increasingly female-specific cardiac dimensional and physiologic data are starting to emerge from comparative studies that may be utilized to address this growing need, and further guide individualized care. Here, we review current literature evaluating female-specific cardiovascular adaptations of the athletic heart, and formulate a discussion on cardiac remodeling, cardiodiagnostic findings, etiologic mechanisms, limitations of currently available data, and direction for future research in the cardiovascular care of female athletes.

Diagnostic electrophysiological study in a highly trained young woman with presyncopal symptoms during exercise: a case report

Right ventricular outflow tract (RVOT) ventricular tachycardia (VT) is frequent and occurs in patients without structural heart disease, especially in highly trained athletes. Most of the studies on cardiac adaptations to exercise have been investigated in male athletes. Women, however, are increasingly participating in sports and electrical and structural adaptations in male and female athletes differ significantly. These cardiac adaptations dissimilarities between males and females have potential implications in diagnosing certain types of arrhythmias. We present here a case of a 35-year-old highly-trained woman endurance athlete that attended the clinic complaining about chest pain and dyspnea on exertion, dizziness and presyncope occurring during maximum-intensity exercise training sessions. An exercise stress testing was performed on cycle ergometer. The test elapsed normally until the patient reached a heart rate of 169 bpm, when she presented identical symptoms to those described during the first interview in the clinic. A wide-complex and notched QRS tachycardia was observed in the inferior leads, inferior axis leads and transition from leads V4 to V5, suspending the test immediately. The patient was referred to perform an electrophysiological study and eventually radiofrequency catheter ablation in order to eliminate the culprit VT. Precocity occurred in the posterior lateral wall of the RVOT, immediately below the pulmonary valve. Radiofrequency application in the arrhythmogenic focus suppressed all ectopic activity despite maintaining isoproterenol infusion. After 30 minutes, the effect was maintained, and the ectopic focus was successfully ablated. The recognition of this clinical entity in females may be challenging since cardiac remodeling in response to exercise may be invaluable due to their biological, anatomical, and hormonal characteristics. In effect, electrical and structural adaptations in males and females may differ considerably. Both exercise stress testing and diagnostic electrophysiological study represent essential and invaluable tools to reach a final diagnosis, especially in highly trained females.

The Female Athlete's Heart: Facts and Fallacies

Purpose of the review

For many years, competitive sport has been dominated by men. Recent times have witnessed a significant increase in women participating in elite sports. As most studies investigated male athletes, with few reports on female counterparts, it is crucial to have a better understanding on physiological cardiac adaptation to exercise in female athletes, to distinguish normal phenotypes from potentially fatal cardiac diseases. This review reports on cardiac adaptation to exercise in females.

Recent findings

Recent studies show that electrical, structural, and functional cardiac changes due to physiological adaptation to exercise differ in male and female athletes. Women tend to exhibit eccentric hypertrophy, and while concentric hypertrophy or concentric remodeling may be a normal finding in male athletes, it should be evaluated carefully in female athletes as it may be a sign of pathology. Although few studies on veteran female athletes are available, women seem to be affected by atrial fibrillation, coronary atherosclerosis, and myocardial fibrosis less than male counterparts.

Summary

Males and females exhibit many biological, anatomical, and hormonal differences, and cardiac adaptation to exercise is no exception. The increasing participation of women in sports should stimulate the scientific community to develop large, longitudinal studies aimed at a better understanding of cardiac adaptation to exercise in female athletes.

How does stress possibly affect cardiac remodeling?

The aim of this study was to evaluate the predictive value of adrenocorticotropic hormone (ACTH), cortisol and ACTH receptor polymorphism (ACTHRP) for left ventricular (LV) remodeling. Thirty-six elite male athletes, as chronic stress adaptation models, and twenty sedentary age and sex-mached subjects emabarked on standard and tissue Doppler echocardiography to assess cardiac parameters at rest. They performed maximal cardiopulmonary test, which was used as an acute stress model. ACTH and cortisol were measured at rest (10min before test), at beginning, at maximal effort, at 3rd min of recovery, using radioimmunometric and radioimmunoassey techniques, respectively. Promoter region of ACTHR gene (18p11.2) was analysed from blood samples using reverse polymerization reaction with the analysis of restriction fragment length polimorphisam by SacI restriction enzyme. Normal genotype was CTC/CTC, heterozygot for ACTHRP CTC/CCC and homozygot CCC/CCC. In all participants, ACTH and cortisol increased during acute stress, whereas in recovery ACTH increased and cortisol remained unchanged. 49/56 examiners manifested CTC/CTC, 7/56 CTC/CCC and 0/56 CCC/CCC. There was no difference in ACTHRP frequency between groups (χ(1)(2)=0.178, p=0.67). LV mass (LVM) and LV end-diastolic volume (LVVd) were higher in athletes than in controls (p<0.01) and lower in CTC/CTC than in CTC/CCC genotype (219.43±46.59(SD)g vs. 276.34±48.86(SD)g, p=0.004; 141.24±24.46(SD)ml vs. 175.29±37.07(SD)ml, p=0.002; respectively). In all participants, predictors of LVM and LVVd were ACTH at rest (B=-1.00,-0.44; β=-0.30,-0.31; p=0.026,0.012, respectively) and ACTHRP (B=56.63,34; β=0.37,0.40; p=0.003,0.001, respectively). These results demonstrate that ACTH and ACTHRP strongly predict cardiac morphology suggesting possible regulatory role of stress system activity and sensitivity in cardiac remodeling.

Impact of ethnicity on cardiac adaptation to exercise

The increasing globalization of sport has resulted in athletes from a wide range of ethnicities emerging onto the world stage. Fuelled by the untimely death of a number of young professional athletes, data generated from the parallel increase in preparticipation cardiovascular evaluation has indicated that ethnicity has a substantial influence on cardiac adaptation to exercise. From this perspective, the group most intensively studied comprises athletes of African or Afro-Caribbean ethnicity (black athletes), an ever-increasing number of whom are competing at the highest levels of sport and who often exhibit profound electrical and structural cardiac changes in response to exercise. Data on other ethnic cohorts are emerging, but remain incomplete. This Review describes our current knowledge on the impact of ethnicity on cardiac adaptation to exercise, starting with white athletes in whom the physiological electrical and structural changes--collectively termed the 'athlete's heart'--were first described. Discussion of the differences in the cardiac changes between ethnicities, with a focus on black athletes, and of the challenges that these variations can produce for the evaluating physician is also provided. The impact of ethnically mediated changes on preparticipation cardiovascular evaluation is highlighted, particularly with respect to false positive results, and potential genetic mechanisms underlying racial differences in cardiac adaptation to exercise are described.

Association of left ventricular mass with the AGTR1 A1166C polymorphism

BACKGROUND

The A1166C polymorphism is located within the microRNA-155 binding site of the human angiotensin II (Ang II) type-1 receptor (AGTR1) gene. The C allele interferes with the base-pairing complementariness between AGTR1 mRNA and microRNA-155 and thereby increases AGTR1 protein expression in vitro. We hypothesized that left ventricular (LV) mass is associated with the AGTR1 A1166C polymorphism.

METHODS

Among 708 individuals (mean age, 49.4 years; 51.8% women) randomly recruited in a white European population, we measured LV structure by two-dimensional guided M-mode echocardiography, the AGTR1 A1166C polymorphism and the 24-h urinary aldosterone. We applied a mixed model to assess phenotype-genotype associations while adjusting for covariables and accounting for relatedness.

RESULTS

The AA (49.1%), AC (42.8%), and CC (8.1%) genotypes were in Hardy-Weinberg equilibrium. Using a recessive model, CC homozygotes compared to A-allele carriers showed significant increases (P < 0.021) in LV mass index (+5.78 ± 2.25 g/m(2)), mean wall thickness (MWT) (+0.48 ± 0.15 mm), interventricular septum (IVS) (+0.60 ± 0.18 mm) and posterior wall thickness (PWT) (+0.34 ± 0.15 mm), but lower 24-h urinary aldosterone excretion (geometric mean, 22.4 vs. 19.0 nmol; P = 0.050). Sensitivity analyses in 552 participants untreated for hypertension were confirmatory.

CONCLUSIONS

LV mass index is associated with the AGTR1 A1166C polymorphism. Further research should clarify to what extent this association might be mediated via different expression of AGTR1 as modulated by microRNA-155.

Influences of the G2350A polymorphism in the ACE gene on cardiac structure and function of ball game players

Background

Except for the I/D polymorphism in the angiotensin I-converting enzyme (ACE) gene, there were few reports about the relationship between other genetic polymorphisms in this gene and the changes in cardiac structure and function of athletes. Thus, we investigated whether the G2350A polymorphism in the ACE gene is associated with the changes in cardiac structure and function of ball game players. Total 85 healthy ball game players were recruited in this study, and they were composed of 35 controls and 50 ball game players, respectively. Cardiac structure and function were measured by 2-D echocardiography, and the G2350A polymorphism in the ACE gene analyzed by the SNaPshot method.

Results

There were significant differences in left ventricular mass index (LVmassI) value among each sporting discipline studied. Especially in the athletes of basketball disciplines, indicated the highest LVmassI value than those of other sporting disciplines studied (p < 0.05). However, there were no significant association between any echocardiographic data and the G2350A polymorphism in the ACE gene in the both controls and ball game players.

Conclusions

Our data suggests that the G2350A polymorphism in the ACE gene may not significantly contribute to the changes in cardiac structure and function of ball game players, although sporting disciplines of ball game players may influence the changes in LVmassI value of these athletes. Further studies using a larger sample size and other genetic markers in the ACE gene will be needed.

The ACE gene and human performance: 12 years on

Some 12 years ago, a polymorphism of the angiotensin I-converting enzyme (ACE) gene became the first genetic element shown to impact substantially on human physical performance. The renin-angiotensin system (RAS) exists not just as an endocrine regulator, but also within local tissue and cells, where it serves a variety of functions. Functional genetic polymorphic variants have been identified for most components of RAS, of which the best known and studied is a polymorphism of the ACE gene. The ACE insertion/deletion (I/D) polymorphism has been associated with improvements in performance and exercise duration in a variety of populations. The I allele has been consistently demonstrated to be associated with endurance-orientated events, notably, in triathlons. Meanwhile, the D allele is associated with strength- and power-orientated performance, and has been found in significant excess among elite swimmers. Exceptions to these associations do exist, and are discussed. In theory, associations with ACE genotype may be due to functional variants in nearby loci, and/or related genetic polymorphism such as the angiotensin receptor, growth hormone and bradykinin genes. Studies of growth hormone gene variants have not shown significant associations with performance in studies involving both triathletes and military recruits. The angiotensin type-1 receptor has two functional polymorphisms that have not been shown to be associated with performance, although studies of hypoxic ascent have yielded conflicting results. ACE genotype influences bradykinin levels, and a common gene variant in the bradykinin 2 receptor exists. The high kinin activity haplotye has been associated with increased endurance performance at an Olympic level, and similar results of metabolic efficiency have been demonstrated in triathletes. Whilst the ACE genotype is associated with overall performance ability, at a single organ level, the ACE genotype and related polymorphism have significant associations. In cardiac muscle, ACE genotype has associations with left ventricular mass changes in response to stimulus, in both the health and diseased states. The D allele is associated with an exaggerated response to training, and the I allele with the lowest cardiac growth response. In light of the I-allele association with endurance performance, it seems likely that other regulatory mechanisms exist. Similarly in skeletal muscle, the D allele is associated with greater strength gains in response to training, in both healthy individuals and chronic disease states. As in overall performance, those genetic polymorphisms related to the ACE genotype, such as the bradykinin 2 gene, also influence skeletal muscle strength. Finally, the ACE genotype may influence metabolic efficiency, and elite mountaineers have demonstrated an excess of I alleles and I/I genotype frequency in comparison to controls. Interestingly, this was not seen in amateur climbers. Corroboratory evidence exists among high-altitude settlements in both South America and India, where the I allele exists in greater frequency in those who migrated from the lowlands. Unfortunately, if the ACE genotype does influence metabolic efficiency, associations with peak maximal oxygen consumption have yet to be rigorously demonstrated. The ACE genotype is an important but single factor in the determinant of sporting phenotype. Much of the mechanisms underlying this remain unexplored despite 12 years of research.

Renin-angiotensin-aldosterone genotype influences ventricular remodeling in infants with single ventricle

BACKGROUND

We investigated the effect of polymorphisms in the renin-angiotensin-aldosterone system (RAAS) genes on ventricular remodeling, growth, renal function, and response to enalapril in infants with single ventricle.

METHODS AND RESULTS

Single ventricle infants enrolled in a randomized trial of enalapril were genotyped for polymorphisms in 5 genes: angiotensinogen, angiotensin-converting enzyme, angiotensin II type 1 receptor, aldosterone synthase, and chymase. Alleles associated with renin-angiotensin-aldosterone system upregulation were classified as risk alleles. Ventricular mass, volume, somatic growth, renal function using estimated glomerular filtration rate, and response to enalapril were compared between patients with ≥2 homozygous risk genotypes (high risk), and those with <2 homozygous risk genotypes (low risk) at 2 time points: before the superior cavopulmonary connection (pre-SCPC) and at age 14 months. Of 230 trial subjects, 154 were genotyped: Thirty-eight were high risk, and 116 were low risk. Ventricular mass and volume were elevated in both groups pre-SCPC. Ventricular mass and volume decreased and estimated glomerular filtration rate increased after SCPC in the low-risk (P<0.05), but not the high-risk group. These responses were independent of enalapril treatment. Weight and height z-scores were lower at baseline, and height remained lower in the high-risk group at 14 months, especially in those receiving enalapril (P<0.05).

CONCLUSIONS

Renin-angiotensin-aldosterone system-upregulation genotypes were associated with failure of reverse remodeling after SCPC surgery, less improvement in renal function, and impaired somatic growth, the latter especially in patients receiving enalapril. Renin-angiotensin-aldosterone system genotype may identify a high-risk subgroup of single ventricle patients who fail to fully benefit from volume-unloading surgery. Follow-up is warranted to assess long-term impact.

CLINICAL TRIAL REGISTRATION

http://www.clinicaltrials.gov. Unique identifier: NCT00113087.

Polymorphisms of renin-angiotensin system genes as a risk factor for high-altitude pulmonary oedema

The genes of the renin—angiotensin system (RAS) play an important role in the regulation of pulmonary vascular tone. Although studies on individual genes polymorphisms have reported association with high-altitude pulmonary oedema (HAPE), studies on multiple genes or epistasis are lacking. We therefore investigated the association of the RAS polymorphisms with HAPE. In a case-control design, we screened 163 HAPE-resistant/controls (HAPE-r) and 160 HAPEpatients (HAPE-p) of Indian origin for eight polymorphisms of four RAS genes, ACE, AGT, AGTR1 and AGTR2. Significant difference in genotype and allele frequencies of the ACE I/D and AGT M235T polymorphisms was observed between HAPE-p and HAPE-r ( p < 0.05). In three-locus haplotype analysis of AGT the haplotype GTM was significantly higher in HAPE-p (29%) and haplotype GTT in HAPE-r (27%) after Bonferroni correction ( p < 0.006). The differences were insignificant for polymorphisms from AGTR1 and AGTR2. The MDR (multifactor dimensional reduction) approach for gene—gene interaction depicted individual polymorphism M235T as the best disease predicting model (cross validation consistency, CVC = 10/10). We found a significant association of D allele of ACE and M allele of AGT with HAPE. The findings are supported at the haplotypic level as well as through nested genetic interaction between the RAS gene polymorphisms using the MDR approach.

Association of echocardiographic left ventricular structure with the ACE D/I polymorphism: a meta-analysis

Introduction: In a previous meta-analysis, we derived pooled estimates for the association of left ventricular mass (LVM) and hypertrophy (LVH), as diagnosed by electrocardiography or echocardiography, with the ACE D/I polymorphism. We updated this meta-analysis until May 2009 only considering echocardiographic phenotypes.

Methods: We computed pooled estimates from a random-effects model.

Results: Across 38 studies, both DD homozygotes ( n = 2440) and DI heterozygotes ( n = 4310) had higher ( p ≤ 0.002) LVM or LVM index than II homozygotes ( n = 2229). Across 21 studies with available data, this was due to increased mean wall thickness (MWT) with no difference in left ventricular internal diameter (LVID). Standardised differences (DD versus II) were 0.39 ( p < 0.001) for LVM, 0.34 ( p = 0.009) for MWT, and 0.066 ( p = 0.26) for LVID. Across 16 studies (4894 participants), the pooled odds ratios of LVH (versus II homozygotes) were 1.11 ( p = 0.29) and 1.02 ( p = 0.88) for the DD and DI genotypes, respectively. Sensitivity analyses were confirmatory.

Conclusions: Our meta-analysis supports the hypothesis that the enhanced ACE activity associated with the D allele is associated with higher LV mass. Smaller sample size might explain the lack of significant association with LVH.

ACE and AGTR1 polymorphisms and left ventricular hypertrophy in endurance athletes

OBJECTIVE

This study aimed to evaluate the role of angiotensin type 1 receptor gene (AGTR1) polymorphism (A1166C) in left ventricular hypertrophy (LVH) mediated by the angiotensin-converting enzyme (ACE) in endurance athletes.

METHODS

A group of 74 white, healthy male endurance athletes, aged between 25 and 40 yr, were enrolled in this study. All of them participated primarily in isotonic sports, training for at least >10 h x wk(-1), for at least 5 yr. The ACE genotype (insertion [I] or deletion [D] alleles) was ascertained by polymerase chain reaction (DD in 35, ID in 36, and II in 3). Group II was excluded from the analysis because of its small size. No difference was found between the two groups as regards age, blood pressure, HR, and echocardiographic data.

RESULTS

The left ventricular mass index (LVMI) was significantly higher in group DD rather than in group ID (P = 0.029). The group DD showed a slightly higher prevalence of subjects with LVH (LVMI > 131 g x m(-2); 62.9%) than group ID (44.4%, P = 0.120). No association was found between ACE-DD and LVH (odds ratio (OR) = 2.12, 95% confidence interval = 0.82-5.46). Concerning the role of AGTR1 polymorphism, the highest LVMI was found in 15 athletes with ACE-DD and AGTR1-AC/CC genotypes (150 +/- 23 g x m(-2)); the lowest value of LVMI was found in the case of ACE-ID and AGTR1-AA (127 g x m(-2) +/- 18 g x m(-2)), whereas LVMI in subjects with ACE-DD + AGTR1-AA was similar to that in the ACE-ID + AGTR1-AC/CC group (134 +/- 18 g x m(-2) vs 133 +/- 20 g x m(-2), P = 0.880). The presence of ACE-DD + AGTR1 + AC/CC was strongly associated with LVH (OR = 4.6, P = 0.029). Moreover, subjects with LVH showed longer left ventricular isovolumetric relaxation time and higher end-systolic wall stress. The latter was strongly correlated to LVMI (r = 0.588), especially in the presence of ACE-DD + AGTR1 + AC/CC (r = 0.728).

CONCLUSIONS

LVMI may be greater in the presence of ACE- DD and AGTR1-AC/CC polymorphisms.

Cardiovascular adaptation, functional capacity and Angiotensin-converting enzyme I/D polymorphism in elite athletes

INTRODUCTION AND OBJECTIVES

Angiotensin-converting enzyme (ACE) is associated with the development of cardiac hypertrophy and improved physical fitness. The objective of this study was to investigate the relationship between the ACE gene insertion/deletion (I/D) polymorphism and adaptation to sports training.

METHODS

The study included 299 elite Spanish athletes (193 men and 106 women) from 32 different sports disciplines, which were grouped according to their static and dynamic components. All participants underwent body composition analysis, Doppler echocardiography at rest, and ergospirometry. Their ACE genotype was determined using the polymerase chain reaction.

RESULTS

The most common genotype in both males and females was the deletion-insertion (DI) heterozygote (57.5% and 54.7%, respectively), followed by the DD homozygote (30.6% and 34.9%), and the II homozygote (11.9% and 10.4%). Differences in morphometric and functional cardiac adaptation were observed between the different sports disciplines, but there was no statistically significant relationship with the ACE I/D polymorphism. Moreover, when athletes with different genotypes were compared, the only differences observed were between the DD and DI groups in female athletes, who differed in body mass index and longitudinal right atrial dimension.

CONCLUSIONS

The ACE I/D polymorphism did not appear to influence cardiovascular adaptation in response to training. However, the DI genotype was the most common, probably because the sample was biased by being made up of elite athletes.

Influence of angiotensinogen and angiotensin-converting enzyme polymorphisms on cardiac hypertrophy and improvement on maximal aerobic capacity caused by exercise training

BACKGROUND

The allele threonine (T) of the angiotensinogen has been associated with ventricular hypertrophy in hypertensive patients and soccer players. However, the long-term effect of physical exercise in healthy athletes carrying the T allele remains unknown. We investigated the influence of methionine (M) or T allele of the angiotensinogen and D or I allele of the angiotensin-converting enzyme on left-ventricular mass index (LVMI) and maximal aerobic capacity in young healthy individuals after long-term physical exercise training.

DESIGN

Prospective clinical trial.

METHODS

Eighty-three policemen aged between 20 and 35 years (mean+/-SD 26+/-4.5 years) were genotyped for the M235T gene angiotensinogen polymorphism (TT, n = 25; MM/MT, n = 58) and angiotensin-converting enzyme gene insertion/deletion (I/D) polymorphism (II, n = 18; DD/DI, n = 65). Left-ventricular morphology was evaluated by echocardiography and maximal aerobic capacity (VO2peak) by cardiopulmonary exercise test before and after 17 weeks of exercise training (50-80% VO2peak).

RESULTS

Baseline VO2peak and LVMI were similar between TT and MM/MT groups, and II and DD/DI groups. Exercise training increased significantly and similarly VO2peak in homozygous TT and MM/MT individuals, and homozygous II and DD/DI individuals. In addition, exercise training increased significantly LVMI in TT and MM/MT individuals (76.5+/-3 vs. 86.7+/-4, P = 0.00001 and 76.2+/-2 vs. 81.4+/-2, P = 0.00001, respectively), and II and DD/DI individuals (77.7+/-4 vs. 81.5+/-4, P = 0.0001 and 76+/-2 vs. 83.5+/-2, P = 0.0001, respectively). However, LVMI in TT individuals was significantly greater than in MM/MT individuals (P = 0.04). LVMI was not different between II and DD/DI individuals.

CONCLUSION

Left-ventricular hypertrophy caused by exercise training is exacerbated in homozygous TT individuals with angiotensinogen polymorphism.

Local renin-angiotensin system regulates left ventricular hypertrophy induced by swimming training independent of circulating renin: a pharmacological study

INTRODUCTION

This study addressed the role of the local renin-angiotensin system (RAS) in the left ventricular hypertrophy (LVH) induced by swimming training using pharmacological blockade.

MATERIALS AND METHODS

Female Wistar rats treated with enalapril maleate (60 mg.kg(-1).d( -1), n=38), losartan (20 mg.kg(-1).d(-1), n=36) or high salt diet (1% NaCl, n=38) were trained by two protocols (T1: 60-min swimming session, 5 days per week for 10 weeks and T2: the same T1 protocol until the 8(th) week, then 9(th) week they trained twice a day and 10(th) week they trained three times a day). Salt loading prevented activation of the systemic RAS. Haemodynamic parameters, soleus citrate synthase (SCS) activity and LVH (left ventricular/body weight ratio, mg/g) were evaluated.

RESULTS

Resting heart rate decreased in all trained groups. SCS activity increased 41% and 106% in T1 andT2 groups, respectively. LVH was 20% and 30% in T1 andT2 groups, respectively. Enalapril prevented 39% of the LVH in T2 group (p<0.05). Losartan prevented 41% in T1 and 50% inT2 (p<0.05) of the LVH in trained groups. Plasma renin activity (PRA) was inhibited in all salt groups and it was increased in T2 group.

CONCLUSIONS

These data provide evidence that the physiological LVH induced by swimming training is regulated by local RAS independent from the systemic, because the hypertrophic response was maintained even when PRA was inhibited by chronic salt loading. However, other systems can contribute to this process.

Keeping pace with ACE: are ACE inhibitors and angiotensin II type 1 receptor antagonists potential doping agents?

In the decade since the angiotensin-converting enzyme (ACE) gene was first proposed to be a 'human gene for physical performance', there have been numerous studies examining the effects of ACE genotype on physical performance phenotypes such as aerobic capacity, muscle function, trainability, and athletic status. While the results are variable and sometimes inconsistent, and corroborating phenotypic data limited, carriers of the ACE 'insertion' allele (the presence of an alu repeat element in intron 16 of the gene) have been reported to have higher maximum oxygen uptake (VO2max), greater response to training, and increased muscle efficiency when compared with individuals carrying the 'deletion' allele (absence of the alu repeat). Furthermore, the insertion allele has been reported to be over-represented in elite athletes from a variety of populations representing a number of endurance sports. The mechanism by which the ACE insertion genotype could potentiate physical performance is unknown. The presence of the ACE insertion allele has been associated with lower ACE activity (ACEplasma) in number of studies, suggesting that individuals with an innate tendency to have lower ACE levels respond better to training and are at an advantage in endurance sporting events. This could be due to lower levels of angiotensin II (the vasoconstrictor converted to active form by ACE), higher levels of bradykinin (a vasodilator degraded by ACE) or some combination of the two phenotypes. Observations that individuals carrying the ACE insertion allele (and presumably lower ACEplasma) have an enhanced response to training or are over-represented amongst elite athletes raises the intriguing question: would individuals with artificially lowered ACEplasma have similar training or performance potential? As there are a number of drugs (i.e. ACE inhibitors and angiotensin II type 1 receptor antagonists [angiotensin receptor blockers--ARBs]) that have the ability to either reduce ACEplasma activity or block the action of angiotensin II, the question is relevant to the study of ergogenic agents and to the efforts to rid sports of 'doping'. This article discusses the possibility that ACE inhibitors and ARBs, by virtue of their effects on ACE or angiotensin II function, respectively, have performance-enhancing capabilities; it also reviews the data on the effects of these medications on VO2max, muscle composition and endurance capacity in patient and non-patient populations. We conclude that, while the direct evidence supporting the hypothesis that ACE-related medications are potential doping agents is not compelling, there are insufficient data on young, athletic populations to exclude the possibility, and there is ample, albeit indirect, support from genetic studies to suggest that they should be. Unfortunately, given the history of drug experimentation in athletes and the rapid appropriation of therapeutic agents into the doping arsenal, this indirect evidence, coupled with the availability of ACE-inhibiting and ACE-receptor blocking medications may be sufficiently tempting to unscrupulous competitors looking for a shortcut to the finish line.

High plasmatic angiotensin-converting enzyme (ACE) activity is not correlated with training-induced left ventricular growth in ACE congenic rats

AIM

The aim of this study was to determine the influence of angiotensin-converting enzyme (ACE) genotype on left ventricular growth after endurance training, in ACE congenic rats with plasma ACE activity twice as high as the donor strain (LOU), thus mimicking the ACE I/D polymorphism observed in humans.

METHODS

LOU and congenic rats (n = 12) were submitted to an endurance training on a treadmill for 7 weeks, while similar LOU and congenic rats (n = 10) constituted the control groups. Blood pressure, skeletal muscle citrate synthase activity, plasma and left ventricular ACE activity were assessed, and echocardiography was performed before and after the training.

RESULTS

Angiotensin-converting enzyme plasmatic activity of congenic rats (188.2 +/- 26.6 in controls and 187.1 +/- 22.6 IU in trained rats respectively) was twofold that of the LOU strain (91.9 +/- 23.3 in controls, and 88.3 +/- 18.1 IU in trained rats respectively). After training, congenic and LOU rats showed a similar significant increase in citrate synthase activity (P < 0.05), and in the left ventricular mass/body mass ratio x 10(3): 3.7 +/- 0.3 and 3.6 +/- 0.6 in the trained congenic and LOU groups, respectively, vs. 3.0 +/- 0.1 and 2.9 +/- 0.2 in the control congenic and LOU groups respectively (P < 0.05). There was no significant correlation between ACE plasma activity and left ventricular mass in trained or untrained congenic rats.

CONCLUSION

We conclude that training-induced left ventricular growth is not associated with plasma ACE activity in congenic rats.

RAAS gene polymorphisms influence progression of pediatric hypertrophic cardiomyopathy

Hypertrophic Cardiomyopathy (HCM) is a disease with variable rate of progression. Young age is an independent risk factor for poor outcome in HCM. The influence of renin-angiotensin-aldosterone (RAAS) genotype on the progression of HCM in children is unknown. Children with HCM (n = 65) were enrolled prospectively across two centers (2001-2005). All subjects were genotyped for five RAAS gene polymorphisms previously associated with LV hypertrophy (pro-LVH): AGT M235T, ACE DD, CMA-1903 A/G, AGTR1 1666 A/C and CYP11B2-344 C/T. Linear regression models, based on maximum likelihood estimates, were created to assess the independent effect of RAAS genotype on LV hypertrophy (LVH). Forty-six subjects were homozygous for <2 and 19 were homozygous for > or =2 pro-LVH RAAS polymorphisms. Mean age at presentation was 9.6 +/- 6 years. Forty children had follow-up echocardiograms after a median of 1.5 years. Indexed LV mass (LVMI) and LV mass z-scores were higher at presentation and follow-up in subjects with > or =2 pro-LVH genotypes compared to those with <2 (P < 0.05). Subjects with > or =2 pro-LVH genotypes also demonstrated a greater increase in septal thickness (IVST) and in LV outflow tract (LVOT) obstruction on follow-up (P < 0.05). On multivariate analysis, a higher number of pro-LVH genotypes was associated with a larger effect size (P < 0.05). Pro-LVH RAAS gene polymorphisms are associated with progressive septal hypertrophy and LVOT obstruction in children with HCM. Identification of RAAS modifier genes may help to risk-stratify patients with HCM.

Small gene effect and exercise training-induced cardiac hypertrophy in mice: an Ace gene dosage study

Small gene effects influence complex phenotypes in a context dependent manner. Here we evaluated whether increasing dosage of the angiotensin I converting enzyme ( Ace) gene influence exercise-induced cardiac hypertrophy. Mice harboring one, two, three, and four copies of the Ace gene were assigned to sedentary (S1–4) and swimming exercise-trained (T1–4) groups (1.5 h twice daily, 5 days/wk, 4 wk). Exercising resulted in comparable bradycardia and elevated skeletal muscle citrate synthase activity, while blood pressure remained unchanged. Left ventricle mass index and cardiomyocyte diameter were similar among sedentary mice and the magnitude of their increase associated to exercising was not influenced by the Ace genotype (T1: 12.6 and 17.9%, T2: 15.2 and 13.8%, T3: 16.9 and 20%, T4: 17 and 19%, respectively). Plasma renin activity (PRA) levels were higher in one vs. three or four copies mice (4.89 ± 0.5 vs. 2.43 ± 0.6 and 2.12 ± 01.1 ng/ml Ang I, P < 0.05), while cardiac ACE activity was higher in three vs. two or one copy mice (5,946 ± 590.8 vs. 2,951.5 ± 328.3 and 3,504.1 ± 258.9 μF·min−1·ml−1, P < 0.05). With exercise, PRA remained unchanged in each group, while cardiac immunostaining for Ang II reached comparable levels. In summary: 1) exercise training led to similar aerobic adaptation regardless of the Ace genotype, and 2) higher number of Ace gene copies per se, which alters cardiac ACE activity, did not influence basal cardiac mass or, most importantly, the magnitude of swimming-induced cardiac hypertrophy. Collectively, these data indicate that small isolated genetic disturbances in ACE cardiac levels can be well compensated under physiological perturbations.

The genetics of left ventricular remodeling in competitive athletes

Left ventricular (LV) remodeling in competitive athletes is a complex phenomenon, in which genetic and environmental determinants are implicated. In recent years, several investigations have demonstrated an association between LV remodeling and the angiotensin-converting enzyme (ACE I/D) and/or angiotensinogen (AGT M/T) polymorphism, with athletes with the DD and/or TT alleles, respectively, showing the greatest increase in LV mass, independent from other determinants. However, the impact of the known genetic determinants on LV remodeling is at present incomplete, and comparative assessment of the genetic and environmental factors, such as the type and intensity of athletic conditioning, suggests that genetic determinants may explain up to one-quarter of the overall variability of LV dimensions. A better understanding of genetic factors may provide an insight into the pathways producing physiological cardiac remodeling, and will be important in understanding the intrinsic nature and clinical significance of the extreme LV morphologic changes observed in highly trained and elite athletes.

Gene-nutrition interaction in human performance and exercise response

Recent advances in human performance research have revealed new insight into the many factors that influence how an individual responds to exercise training. Response to exercise interventions is often highly variable among individuals, however, and exercise response may be mediated in large part by variation in genes and nutrition and by gene-environment interactions. It is well established that the quality and quantity of nutritional intake play a critical role in response to training and in athletic performance. The body's adaptation to exercise is also the result of changes in expression of genes mediated not only by exercise but by multiple factors, including the interaction between exercise, components of dietary intake, and genetic variation. This review explores the effects of genetic variation and gene-nutrition interactions in response to exercise training and athletic performance.

Genes and human elite athletic performance

Physical fitness is a complex phenotype influenced by a myriad of environmental and genetic factors, and variation in human physical performance and athletic ability has long been recognised as having a strong heritable component. Recently, the development of technology for rapid DNA sequencing and genotyping has allowed the identification of some of the individual genetic variations that contribute to athletic performance. This review will examine the evidence that has accumulated over the last three decades for a strong genetic influence on human physical performance, with an emphasis on two sets of physical traits, viz. cardiorespiratory and skeletal muscle function, which are particularly important for performance in a variety of sports. We will then review recent studies that have identified individual genetic variants associated with variation in these traits and the polymorphisms that have been directly associated with elite athlete status. Finally, we explore the scientific implications of our rapidly growing understanding of the genetic basis of variation in performance.

ACE I/D Polymorphism and Cardiac Adaptations in Adolescent Athletes

PURPOSE

The aim of this cross-sectional study was to determine whether there is a correlation between left ventricular hypertrophy (LVH) and angiotensin converting enzyme (ACE) insertion/deletion (I/D) polymorphism in adolescent athletes.

METHODS

Seventy-five competitive soccer players (aged 15 +/- 1.2 yr) and 52 untrained control subjects (aged 15 +/- 1.6 yr) were examined with echocardiography (echo) and bioelectrical impedance analysis. The ACE genotype of all subjects was determined by PCR and correlated with left ventricular mass (LVM) indices.

RESULTS

Allele frequencies were comparable between athletes and controls. Body surface area (BSA), fat-free mass (FFM), and all mean echo measurements were significantly greater in athletes than in controls. LVM and LVM indices for both BSA and FFM were all significantly greater in athletes than in controls (LVM 195.3 +/- 32 g vs 165.3 +/- 37.6 g; LVM/BSA 115.5 +/- 18.9 g x mq(-1) vs 95 +/- 18.2 g x mq(-1); LVM/FFM 3.5 +/- 0.5 vs 3 +/- 0.54, P < 0.001 for the three variables). Left ventricular hypertrophy was found in 17 (23%) athletes. There was no correlation between ACE I/D polymorphism and athletes with LVH as the II and DD genotype frequencies were identical (41%). However, in athletes with LVH, the presence of the D allele was associated with a greater LVM index than compared to homozygous II genotype (LVM = 145 +/- 7.6 g x mq(-1) in DD+ID group vs 135 +/- 2.9 g x mq(-1) in II group, P = 0.008).

CONCLUSIONS

The results of the study show that significant changes occur in cardiac morphology and function in adolescent athletes. Interestingly, the ACE I/D polymorphism was associated with the degree of cardiac hypertrophy but not with the occurrence of LVH itself.

The ACE/DD genotype is associated with the extent of exercise-induced left ventricular growth in endurance athletes

OBJECTIVES

We studied the impact of the angiotensin-converting enzyme (ACE)/DD genotype on morphologic and functional cardiac changes in adult endurance athletes.

BACKGROUND

Trained athletes usually develop adaptive left ventricular hypertrophy (LVH), and ACE gene polymorphisms may regulate myocardial growth. However, little is known about the impact of the ACE/DD genotype and D allele dose on the cardiac changes in adult endurance athletes. METHODS; Echocardiographic studies (including tissue Doppler) were performed in 61 male endurance athletes ranging in age from 25 to 40 years, with a similar period of training (15.6 +/- 4 h/week for 12.6 +/- 5.7 years). The ACE genotype (insertion [I] or deletion [D] alleles) was ascertained by polymerase chain reaction (DD = 27, ID = 31, and II = 3). Athletes with the DD genotype were compared with their ID counterparts.

RESULTS

The DD genotype was associated with a higher left ventricular mass index (LVMI) than the ID genotype (162.6 +/- 36.5 g/m(2) vs. 141.6 +/- 34 g/m(2), p = 0.031), regardless of other confounder variables. As a result, 70.4% of DD athletes and only 42% of ID athletes met the criteria for LVH (p = 0.037). Although systolic and early diastolic myocardial velocities were similar in DD and ID subjects, a more prolonged E-wave deceleration time (DT) was observed in DD as compared with ID athletes, after adjusting for other biologic variables (210 +/- 48 ms vs. 174 +/- 36 ms, respectively; p = 0.008). Finally, a positive association between DT and myocardial systolic peak velocity (medial and lateral peak S(m)) was only observed in DD athletes (p = 0.013, r = 0.481).

CONCLUSIONS

The ACE/DD genotype is associated with the extent of exercise-induced LVH in endurance athletes, regardless of other known biologic factors.

Polymorphisms in the RAS and cardiac function

Since the discovery of the polymorphism in the angiotensin converting enzyme (ACE) and the consequences of this polymorphism on the activity levels of the enzyme, numerous association studies have been performed. However, these investigations do not often adhere to the most stringent criteria for such studies. The initial study reporting a positive association of the ACE polymorphism and myocardial infarction showed an increased risk of the DD genotype. This initial association was eventually refuted by a large, well conducted association study, which found a risk ratio of 1.02 after combining their own data with all published data. Although such large, well conducted association studies have not been performed in left ventricular (LV) hypertrophy, the association between DD genotype and hypertrophy is more convincing with a 192% excess risk of LV hypertrophy in untreated hypertensives. The role of ACE genotype in LV growth is well established, especially in athletes. In heart failure, large studies or meta-analyses have not been performed, because most studies have selected different end-points. This hampers a proper meta-analysis of the results obtained in associations with heart failure. As most association studies do not fulfill the criteria for good association studies and use too small sample sizes, it remains important to perform a meta-analysis to add meaning to the results of such studies. Above all, it is important to obey the rules set for association studies, large sample size, small P values, report associations that make biological sense and alleles that affect the gene product in a physiologically meaningful way.

Cardiac hypertrophy and remodeling in relation to ACE and angiotensinogen genes genotypes in Chinese dialysis patients

BACKGROUND

Genetic polymorphisms of the angiotensinogen (AGT) and angiotensin-converting enzyme (ACE) genes are associated with increased risk of hypertension and left ventricular hypertrophy (LVH) in hypertensive subjects. However, the extent to which these polymorphisms are related to LVH and remodeling in dialysis patients remains unknown.

METHODS

Two hundred and forty-six end-stage renal disease (ESRD) patients on peritoneal dialysis and 183 control subjects, all of Chinese origin, were genotyped for the ACE insertion/deletion (I/D) and the AGT M235T gene polymorphisms. Left ventricular mass index (LVMi) and relative wall thickness were measured using echocardiography.

RESULTS

Prevalence of ACE DD and AGT TT genotype was 14% and 83%, respectively, in ESRD patients and did not differ significantly from controls. A total percentage of 95% of our patients had LVH (171 with concentric and 63 with eccentric hypertrophy). Adjusting for age, gender, body mass index, duration of dialysis, diabetes, renal diagnosis, hematocrit, systolic and diastolic blood pressure, dialysis urea clearance, residual glomerular filtration rate, and use of converting enzyme inhibitors or angiotensin receptor blockers, AGT TT genotype remained independently associated with greater LVMi (coefficient = 28.73; 95% CI, 5.72 to 51.75; P = 0.015) and relative wall thickness (coefficient = 0.072; 95% CI, 0.022 to 0.122; P = 0.005) than MT/MM genotypes. LVMi and relative wall thickness did not differ significantly among patients with DD, DI, and II genotypes. No statistical significant interaction was noted between ACE and AGT gene polymorphism in relation to LVMi and relative wall thickness.

CONCLUSION

Polymorphism of the AGT M235T gene but not ACE I/D gene is associated with greater LVMi and relative wall thickness, indicating more concentric LVH, in Chinese peritoneal dialysis patients. Possible synergistic effects between AGT and ACE gene polymorphism require further evaluation in a larger population.