Leukocyte Intracellular pH and Na/H Antiporter Activity in Uraemia and Type I Diabetes Mellitus

Abstract

The leukocyte Na/H antiporter has been studied in patients with end-stage renal failure on maintenance haemodialysis. Thirteen non-diabetic haemodialysis patients (CRF group) and eight haemodialysis patients with diabetic nephropathy (CRF-DM group) were investigated. Measurements were made using the pH-sensitive fluorescent dye bis (carboxyethyl) carboxyfluorescein (BCECF). The initial intracellular pH (pHi), intracellular buffering capacity, and Na/H antiporter Vmax (at pHi = 6.0) have been recorded in bicarbonate-free solutions. The mean initial intracellular pH in the CRF group was 7.34 (SD 0.05, P less than 0.004) and this was significantly less than the CRF-DM group (7.42, SD 0.07) and normal controls (7.43, SD 0.09, n = 25). The mean intracellular buffering capacity was normal in the CRF and CRF-DM groups. The mean Na/H antiporter Vmax was also normal in the CRF and CRF-DM groups (56.5, SD 9.9; and 56.8, SD 12.8, mmol/l per min respectively compared to 55.2, SD 8.8, mmol/l per min in controls). These data are discussed with reference to the reported high values of Na/H antiporter Vmax in diabetic patients with early nephropathy. This abnormality does not appear to be present in end-stage diabetic nephropathy.

Lymphocytic Intracellular pH and Na⁺/H⁺ Exchanger Activity in Hemodialysis Patients

“…Our data are partly at variance with those of Poli de Figueiredo et al [4], who showed normal Na+/H + anti porter activity in nondiabetic uremic HD patients; how ever, they did find reduced Na+/H + antiporter activity in diabetic HD patients in comparison with nonuremic dia betic controls, indirectly confirming a depressing effect of uremia on Na+/H + exchanger activity. In another recent study there was an increase of both Na+/H + activity and protein density in red blood cells [23].…”

“…in the absence of HCO 3/CO2) was lower than normal in lympho cytes from HD patients. It is worth noting that also other investigations showing intracellular acidosis in uremia [4,5] were performed in peripheral lymphocytes kept in Hepes solution. Thus, it would appear that uremic cells are somehow unable to properly regulate pH; in the absence of the physiological buffer HCO3/CO2.…”

“…Recently, pH; in both erythrocytes [3] and peripheral leukocytes [4,5] from nondiabetic hemodialysis (HD) patients has been shown to be lower than in healthy sub-jects. However, other investigations in man [6][7][8][9][10] and in animals [1 1 , 1 2 ] have found normal pH; in uremia.…”

Analysis of the Spectroscopic Aspects of Cationic Dye Basic Orange 21

“…pH: is known to vary within a cell, [31][32][33] and hence raise the question of whether different levels of acidity might differently affect intracellular BO21 color, as it is a pH sensitive chromophore. 34,35 Given that intracellular pH ranges from about 5 to 8, 33 the absorption spectra of 10µM BO21 in PBS with pH levels ranging from 5.15 to 7.94 was measured, relevant area ratios d1/d2 were calculated and results depicted in Figure 3.…”

“…This is known to vary within a cell − and hence raise the question as to whether different levels of acidity might differently affect the intracellular BO21 color, as it is a pH-sensitive chromophore. , Given that intracellular pH ranges from about 5 to 8, the absorption spectra of 10 μM BO21 in PBS with pH levels ranging from 5.15 to 7.94 was measured; relevant area ratio d1/d2 was calculated, and the results are depicted in Figure . As can be seen, except for a negligible decrease in its intensity (at high pH), the nature of BO21 absorption spectra is insensitive to the pH values within said range, a finding which is further strengthened by the constancy of ratio d1/d2 (Figure right panel).…”