Deletion polymorphism of the angiotensin-converting enzyme gene is independently associated with left ventricular mass and geometric remodeling in systemic hypertension

Erythrocyte calpain activity and left ventricular mass in essential hypertension

BACKGROUND

Calpains are cytoplasmic proteases widely distributed among eucaryotic cells. Low levels of calpain activity were found in hypertrophic hearts from hypertensive rats, but its role in hypertrophic hearts from human hypertensives is unknown. Therefore, calpain activity was investigated in erythrocytes from essential hypertensive patients in relation to their left ventricular mass.

OBJECTIVE

To study the role of calpain activity in the development of left ventricular hypertrophy (LVH) in human essential hypertension.

METHODS

A total of 115 hypertensives (72 untreated and 43 with treatment interrupted for at least 4 months) were included in the study. Calpain I activity was measured in human erythrocytes and LVH was measured as left ventricular mass index (LVMI) by M-mode echocardiography.

RESULTS

Values are given as mean+/-SEM. The hypertensives (97 men and 18 women) were 43.5+/-0.9 years old with mild to moderate levels of hypertension (systolic/diastolic blood pressure of 147.9+/-1.4/98.7+/-0.9 mmHg) and relatively recent LVH onset (3.5+/-0.5 years). An inverse relation between LVMI and erythrocytic calpain activity was present in all (P = 0.0023, R2 = 7.9%). This relation was still present considering only untreated hypertensives (P = 0.008; R2 = 9.7%), but was lost in the 43 previously treated hypertensives. Moreover, in the untreated hypertensives, after excluding the possible confounding effects of sex, age, body mass index, blood pressure and duration of hypertension, a stepwise regression showed that only two variables remained significantly related to LVMI: calpain (F = 6.23) and mean arterial pressure (F = 4.689). No relations were found between LVMI and calpastatin activity either in the whole population, or in treated or untreated hypertensives.

CONCLUSIONS

If we assume that the level of erythrocyte calpain activity mirrors the level in cardiomyocytes, these data seem to suggest that increased protein degradation by calpain may prevent the development of LVH in hypertensive patients. This effect is independent of the duration and severity of hypertension.

The application of molecular genetic techniques to the study of hypertensive diseases

The techniques of modern molecular genetics are shedding new light on hypertension and its sequelae. This article discusses techniques which have identified genes associated with hypertension and have pointed the way toward identifying the full cohort of genes operative in all forms of human hypertension. These techniques have expanded understanding of the pathophysiology of hypertension as well as its prevention.

Association of angiotensin-converting enzyme gene I/D polymorphism with change in left ventricular mass in response to physical training

BACKGROUND

The absence (deletion allele [D]) of a 287-base pair marker in the ACE gene is associated with higher ACE levels than its presence (insertion allele [I]). If renin-angiotensin systems regulate left ventricular (LV) growth, then individuals of DD genotype might show a greater hypertrophic response than those of II genotype. We tested this hypothesis by studying exercise-induced LV hypertrophy.

METHODS AND RESULTS

Echocardiographically determined LV dimensions and mass (n=140), electrocardiographically determined LV mass and frequency of LV hypertrophy (LVH) (n=121), and plasma brain natriuretic peptide (BNP) levels (n=49) were compared at the start and end of a 10-week physical training period in male Caucasian military recruits. Septal and posterior wall thicknesses increased with training, and LV mass increased by 18% (all P<.0001). Response magnitude was strongly associated with ACE genotype: mean LV mass altered by +2.0, +38.5, and +42.3 g in II, ID and DD, respectively (P<.0001). The prevalence of electrocardiographically defined LVH rose significantly only among those of DD genotype (from 6 of 24 before training to 11 of 24 after training, P<.01). Plasma brain natriuretic peptide levels rose by 56.0 and 11.5 pg/mL for DD and II, respectively (P<.001).

CONCLUSIONS

Exercise-induced LV growth in young males is strongly associated with the ACE I/D polymorphism.