Background We studied the frequency of insertion-deletion polymorphism of the ACE gene in patients with arterial hypertension and associations of this polymorphism with blood pressure profiles, albuminuria, and sodium sensitivity recognized as markers of early cardiovascular events.
Material and methods The study group consisted of 69 patients with stage I or II essential arterial hypertension according to the Polish Arterial Hypertension Society. Patients were hospitalized and were given a controlled diet in 7-day cycles containing 100-120 mmol, 10-20 mmol, and 220-240 mmol of sodium per day. 24 h urine collection was started on day 6 and 7 of the high- and low-sodium diet cycle. We measured urine volume and excretion of sodium, potassium, creatinine, and albumin. 24 h blood pressure monitoring according to ABPM was started on day 7 of the high- and low-sodium diet cycle. During each diet cycle venous blood was sampled and ARO, ALDO, sodium, potasssium, and creatinine concentrations were determined using routine laboratory methods. 10 ml venous blood was obtained on a single occasion and DNA was isolated for PCR assessment of I/D polymorphism of the ACE gene.
Results A higher frequency of the DD genotype and D allele was noted in sodium-sensitive patients. During the low-sodium cycle, sodium-sensitive patients regardless of the I/D genotype demonstrated similar UAE, Ccr, UNa, UK, Uvol, mean 24 h, day and night blood pressure values, as well as nocturnal dip in blood pressure (N/D). During the high-sodium cycle, 24MAP, DMAP, NMAP and STD increased and the nocturnal dip in blood pressure decreased significantly in the genotype groups. The mean N/D value was nevertheless smaller in DD patients. UAE and Ccr increased to a greater extent during the high-sodium diet in DD patients. In DD patients as compared with ID/II patients, ARO and ALDO were modestly but significantly higher on the low-sodium diet and the rise in ARO and ALDO values was significantly suppressed on the high-sodium diet.
Conclusions 1. The deletion genotype (DD) is found more often in Caucasian sodium-sensitive hypertensive patients.
2. High-sodium diet induced a smaller nocturnal dip in blood pressure, greater albuminuria, and smaller reduction in ARO and ALDO values in DD hypertensive patients, suggesting that hypertension combined with a high-sodium diet will over a shorter period of time produce cardiovascular and renal complications in patients with the DD genotype.