SALT AND WATER-RETENTION AND CALCIUM BLOCKADE IN UREMIA

Blood pressure, echocardiography, and aortic and peripheral arterial pulse-wave velocity were studied in 40 hypertensive patients on long-term hemodialysis during a 24-week administration of nitrendipine (1,4-dihydro-2,6-dimethyl-4-[m-nitrophenyl]-3,5-pyridine-dicarboxylic acid ethyl methylester) monotherapy. In a double-blind placebo-randomized study, nitrendipine effectively lowered the blood pressure (p<0.001) before hemodialysis without causing postdialysis hypotension. The antihypertensive effect of nitrendipine was greater in patients with significant salt and water retention, as indicated by interdialytic body weight gain (ΔBW), that is, a significant correlation was observed between ΔBW and the decrease in blood pressure (r=0.72; p<0.001). The antihypertensive effect was not related to age, pretreatment plasma renin activity, or serum-ionized calcium concentration. After nitrendipine, a time-related decrease in aortic (p<0.005) and femoral (p<0.05) pulse-wave velocity was observed with a significant time-treatment interaction (p<0.01). Nitrendipine treatment did not influence left ventricular mass (which was positively correlated with ΔBW; p<0.01) but was associated with an increase in the left ventricular ejection fraction. The increase in ejection fraction was correlated with changes in aortic pulse-wave velocity (r=0.548; p<0.02) but not with changes in blood pressure (r=0.352; p=0.19) or ΔBW. This study shows that in patients on hemodialysis, 1) the antihypertensive effect of nitrendipine is related to sodium and water retention, 2) the long-term administration of nitrendipine increases aortic distensibility but does not influence left ventricular hypertrophy, and 3) the increase in aortic distensibility is associated with an improvement in left ventricular function.