2--7--bis(carboxyethyl)-5(6)-carboxyfluorescein and Kidney-Failure--Chronic

Cytosolic pH (pHi) and Na+/H+ exchange activity were measured in lymphocytes from 22 patients with mild chronic renal failure, and 21 age- and sex-matched normotensive healthy control subjects using the fluorescent dye technique. The basal pHi in resting lymphocytes was not significantly different in both groups tested (control, pHi 7.18 +/- 0.04; patients with mild chronic renal failure, 7.17 +/- 0.05). The initial rate of pHi recovery immediately after intracellular acidification with 100 mmol/l propionic acid, representing the maximum Na+/H+ exchange activity, was significantly higher in lymphocytes from patients with mild chronic renal failure (7.10 +/- 0.52 dpHi/s, mean +/- SEM) when compared with control subjects (5.42 +/- 0.47 dpHi/s; p < 0.05). No significant correlation between Na+/H+ exchange activity and blood pressure could be obtained in patients with mild chronic renal failure. Furthermore, there was no relationship of Na+/H+ exchange activity to cytosolic pH or extracellular pH. It is concluded that an enhanced Na+/H+ exchange activity can be detected in patients with mild chronic renal failure and may not be related to the significant abnormalities of electrolyte and acid-base metabolism commonly observed in patients with end-stage renal failure or on hemodialysis.

Topics: Acid-Base Equilibrium; Acidosis; Adult; Bicarbonates; Blood Pressure; Female; Fluoresceins; Fluorescent Dyes; Humans; Hydrogen-Ion Concentration; Kidney Failure, Chronic; Kidney Function Tests; Lymphocytes; Male; Middle Aged; Propionates; Sodium-Hydrogen Exchangers

The Na+/H+ exchange antiport activity was measured in lymphocytes from 16 patients with end-stage renal failure pre- and postdialysis. In addition the effect of the patients' plasma on lymphocytes from healthy subjects was tested. Resting pH (pHi) was not significantly different in lymphocytes pre- and postdialysis. On the other hand, the Na+/H+ exchange activity was significantly lower in lymphocytes before hemodialysis (6.22 +/- 0.73 x 10(-3) pHi/s) than after hemodialysis (9.32 +/- 1.58 x 10(-3) pHi/s; n = 16; p < 0.05). The buffer capacity was not significantly different before and after hemodialysis. The incubation of lymphocytes from healthy control subjects with plasma from patients with end-stage chronic renal failure significantly reduced the lymphocytic Na+/H+ exchange activity. The addition of ultrafiltrate also significantly reduced the Na+/H+ exchange activity in lymphocytes from healthy control subjects. The study indicates the existence of an endogenous inhibitor of the Na+/H+ exchange that is accumulated in plasma from patients with end-stage chronic renal failure.

Topics: Adult; Female; Fluoresceins; Fluorescent Dyes; Humans; Hydrogen-Ion Concentration; Kidney Failure, Chronic; Lymphocytes; Male; Renal Replacement Therapy; Sodium-Hydrogen Exchangers

We have evaluated intracellular pH (pHi) and Na+/H+ exchanger activity in peripheral lymphocytes from 16 patients on regular acetate hemodialysis. All the patients were taking oral NaHCO3 supplementation (30 mmol/day), to maintain predialysis arterial blood acid-base status within normal range (pH 7.36 +/- 0.02, PHCO3- 23.3 +/- 1.2 mM, pCO2 40.9 +/- 1.4 mm Hg). pHi was measured, using the fluorescent probe BCECF (2',7'-bis-carboxyethyl-5,6-carboxyfluorescein), both in nominal absence of bicarbonate (Hepes solution, pH 7.4; n = 10) and in the presence of HCO3-/CO2 buffer system (pH 7.4, [HCO3-] 25 mM, pCO2 40 mm Hg; n = 6). Predialysis pHi did not differ from controls when measured in the presence of HCO3-/CO2 (7.28 +/- 0.04 vs. 7.29 +/- 0.04, p = NS), but was lower in dialysis patients than in normal subjects (7.11 +/- 0.04 and 7.20 +/- 0.02, respectively; p < 0.05) when measured in Hepes solution. This suggested that bicarbonate-independent pHi regulation was abnormal in dialysis patients. To further characterize this abnormality of pHi regulation, lymphocytes were exposed to ethylisopropylamiloride, a specific Na+/H+ antiporter inhibitor, in Hepes solution; this maneuver induced a significantly lower decrement in pHi (0.04 +/- 0.04 vs. 0.15 +/- 0.03, p < 0.05) in dialysis patients than in controls, indicating reduced Na+/H+ exchanger activity in the patients. The rate of pHi recovery during the first 30 s after induction of various degrees of cell acidification (pHi range 6.2-7.0), which in the absence of HCO3-/CO2 is dependent on Na+/H+ exchanger activity, was also reduced in the patients as compared to controls (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adult; Aged; Amiloride; Cell Separation; Female; Flow Cytometry; Fluoresceins; Fluorescent Dyes; Humans; Hydrogen-Ion Concentration; Kidney Failure, Chronic; Male; Middle Aged; Renal Dialysis; Sodium Bicarbonate; Sodium-Hydrogen Exchangers; T-Lymphocytes