Potassium depletion is a risk factor for cardiovascular diseases, including hypertension, and frequently is encountered in patients with end-stage renal disease. Since the treatment of end-stage renal disease might result in K+ depletion and postdialysis hypokalemia, we investigated the relationship between acute K+ removal by hemodialysis and changes in blood pressure at the completion of treatment compared with predialysis and 1-hour postdialysis blood pressure. The effects of three different dialysate potassium concentrations ([K+]d; 1.0, 2.0, and 3.0 mmol/L) were investigated in 11 patients. Hemodialysis-induced K+ removal, serum [K+], total body K+, and blood pressure were measured. The use of 1.0, 2.0, or 3.0 mmol/L [K+]d resulted in the removal of 77.0 +/- 6.5, 54.5 +/- 7.9, and 42.5 +/- 9.9 mmol of K+ per treatment, respectively (P < 0.05, [K+]d 1.0 v [K+]d 3.0). Predialysis and postdialysis serum [K+] were 4.9 +/- 0.2 and 3.6 +/- 0.1 mEq/L for 1.0 mmol/L [K+]d, 5.1 +/- 0.3 and 3.9 +/- 0.1 mEq/L for 2.0 mmol/L [K+]d, and 5.3 +/- 0.3 and 4.2 +/- 0.2 mEq/L for 3.0 mmol/L [K+]d, respectively (P < 0.001 for each [K+]d). The baseline total body K+ corrected for gender, age, and race was 92% of predicted normal level and did not change significantly with the use of different [K+]d. Blood pressure decreased during hemodialysis as excess fluid was removed, regardless of [K+]d. Significant increases in blood pressure did occur 1 hour postdialysis compared with levels measured at the completion of treatment ("rebound hypertension") when hemodialysis was performed with 1.0 and 2.0 mmol/L, but not with 3.0 mmol/L [K+]d.(ABSTRACT TRUNCATED AT 250 WORDS)