Hormonal mechanisms in blood pressure reduction during hemodialysis in patients with chronic renal failure.

To elucidate the hormonal mechanisms of blood pressure (BP) reduction during hemodialysis in patients with chronic renal failure (CRF), we performed this study using 7 normotensive (NT) and 17 hypertensive (HT) patients who were strictly matched in age, body weight, body weight gain from the last HD, and duration of HD. Blood pressure, pulse rate, plasma norepinephrine (NE), and plasma dopamine levels were used as indices of sympathetic nerve activity, before, at 50% of hemodialysis (HD) and at 100% of HD (at the end of HD) on the third day after the last HD. As hemodialytic BP reduction was defined as BP decline of more than 10% in pre-HD mean BP, in normotensive patients with CRF, hemodialytic BP reduction was recognized in 0/7 (0%) at 50% of HD and 4/7 (57%) at 100% of HD, and in hypertensive patients it was recognized in 3/17 (18%) at 50% of HD and 4/17 (24%) at 100% of HD. Percentile changes in plasma NE levels increased slightly following hemodialysis in normotensive patients with hemodialytic BP reduction and in hypertensives without BP reduction, while those in normotensives without BP reduction and in hypertensives with BP reduction did not change. However, percentage changes in plasma dopamine (DA) levels decreased significantly at the end of HD (NT; p < 0.05, HT; p < 0.01) following hemodialysis in both normotensive and hypertensive patients with hemodialytic BP reduction, while changes in patients without BP reduction, percentage changes in DA did not change (patients with BP reduction vs. patients without BP reduction). In conclusion, hemodialytic BP reduction may be predisposed by abnormal sympathetic nerve responsiveness.