No abstract

Defect in renal salt excretion may play an important role in the pathogenesis of hypertension. We examined sodium (Na+) uptake by brush border membrane (BBM) vesicles of young (6 week old) spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY) of the same age. SHR had lower urinary Na+ excretion (223.1 +/- 9.3 vs. 266.3 +/- 3.7 microEq/day/100 g, N = 8, P less than 0.01) and higher systolic blood pressure (98.9 +/- 1.2 vs. 82.9 +/- 1.8 mm Hg, N = 8, P less than 0.01) than WKY. BBM vesicle Na+ uptake, measured by rapid filtration technique, was higher in SHR when compared to WKY (1.44 +/- 0.03 vs. 1.01 +/- 0.06 nmol/mg/5 sec, N = 4, P less than 0.01). This increase in Na+ influx was apparent only in the present of an outward-directed proton (H+) gradient and was abolished by 1 mM amiloride. BBM permeability to H+ as assessed by acridine orange quenching was not different between SHR and WKY. Kinetic analyses of the amiloride-sensitive BBM Na+ uptake revealed a higher Vmax (2.13 +/- 0.27 vs. 0.70 +/- 0.30 nmol/mg/5 sec, N = 4, P less than 0.01) and a higher km for Na+ (3.55 +/- 0.32 vs. 1.23 +/- 0.14 mM, N = 4, P less than 0.05) in SHR. These findings thus demonstrate an intrinsic derangement in BBM Na+ transport in young SHR which is characterized by increased Na+/H+ antiport activity. This alteration in antiport activity is not attributable to changes in membrane permeability to H+, and is characterized by higher Vmax and km.(ABSTRACT TRUNCATED AT 250 WORDS)

Successful treatment of patients with end-stage renal failure requires, in addition to dialysis, strict control of dietary, fluid and medication intake. In the present study we measured, in 50 chronic hemodialysis patients, serum potassium (K), serum phosphate (PO₄) and interdialytic weight gain as indices of diet, medication and fluid compliance, respectively. Dietary compliance did not correlate with fluid or medication compliance, whereas fluid intake and medication compliance were related (p = 0.01). Age, time on dialysis, place of birth and whether the patient came accompanied or not to the dialysis unit were the main variables affecting serum K levels. Sex, ethnic origin and education significantly affected serum PO₄. Sex, place of birth, marital status, number of children and years of education affected fluid intake. The compliance of the hemodialysis patient with different aspects of his regimen is thus multifactorial. Attempts to improve compliance and thus reduce morbidity and mortality should be aimed at identifying the population with low compliance and exposing them to educational programs.

Thirty-six haemodialysis patients on treatment for more than six months were studied for residual renal function (RRF). Twenty patients were anuric. The remaining 16 patients with RRF excreted 35-1600 ml urine/day with creatinine clearance ranging 0.17-6.95 ml/min. Patients with RRF were on dialysis therapy for shorter periods than those with anuria (25.5 +/- 18.5 vs. 101.7 +/- 14.2 months, p = 0.001). Twelve out of 20 anuric patients had had previous renal transplantation, whereas none of those with RRF had been transplanted (p = 0.0006). Interdialytic weight gain, serum potassium and phosphate were lower in patients with RRF. Serum phosphate and uric acid were correlated with their respective urinary excretion rates (p = 0.013 and 0.005, respectively), but interdialytic weight gain could not be correlated with urinary output. Creatinine clearance significantly correlated with urinary excretion of potassium, sodium, phosphate and uric acid. In this series of patients a previous unsuccessful renal transplantation was an important factor in the loss of RRF. The presence of RRF contributed to the regulation of the blood levels of phosphate and the excretion rate of potassium, sodium and uric acid.

No abstract