Influence of the CYP11B2 -344C/T polymorphism on plasma aldosterone, sodium excretion and blood pressure responses to aerobic exercise training in middle-aged to older prehypertensives

Abstract

Aldosterone influences renal Na+ handling and normal blood pressure (BP) regulation but if consistently elevated, aldosterone may contribute to the development of hypertension. A few studies have found that as with BP, plasma aldosterone (PA) levels can change with aerobic exercise training (AEX) in hypertensives, but the response of these phenotypes to AEX vary by individual. The CYP11B2 (-344C/T) gene polymorphism has been associated with variability in both blood pressure and urinary and PA levels among hypertensives and may help explain the response of these phenotypes to AEX. The purpose of this study was to determine if the -344C/T polymorphism was associated with changes in PA levels, 24-hour Na+ excretion and BP after 6 months of AEX in middle-aged to older White prehypertensives. 23 Caucasian disease free, sedentary prehypertensives completed a standardized AEX program. All participants followed the AHA Step 1 diet. Blood samples were collected under fasting and supine conditions and PA was measured by RIA. The T and C allele frequencies were 0.61 and 0.39, respectively. There were 9 participants in the TT genotype group and 13 in the TC+CC genotype group. The TC+CC genotype group tended to decrease PA levels (−39±21 pg/ml, p=0.09) and had a greater reduction in PA levels with AEX than the TT genotype group after accounting for baseline plasma aldosterone levels (TC+CC −47±8 pg/ml; TT: −23±10 pg/ml, p<0.001). The TC+CC genotype group significantly decreased systolic BP (−4±2 pg/ml, p=0.03) and had a greater reduction in systolic BP with AEX than the TT genotype group after accounting for baseline systolic BP (TC+CC −4±1pg/ml; TT: −2±2 mm Hg, p<0.02). Neither genotype group changed diastolic BP or 24 hour Na+ excretion and there was no difference in the change in diastolic BP and 24-hour Na+ excretion between the two genotype groups. Based on this preliminary evidence, the presence of the C allele among prehypertensives is associated with a greater reduction in plasma aldosterone and systolic BP with AEX.