Acid-base transport in Henle's loop: the effects of reduced renal mass and diabetes.

The loop of Henle (LOH) is an important site of renal acidification. Using the in vivo microperfusion technique of LOH combined with quantitative polymerase chain reaction (PCR) performed on isolated thick ascending limbs (TAL), we demonstrated that the Na + -H + exchanger is the main transport mechanism involved, although a small, but significant contribution from the H+-ATPase also occurs. Among the various Na+-H+ exchanger isoforms we have evidenced that NHE3 is expressed and functionally active along the TAL. Since the LOH is exposed to osmotic stress, bicarbonate transport was also measured under medullary hypotonicity conditions, which led to the stimulation of bicarbonate reabsorption. We demonstrated that the LOH can participate in the tubular adaptation to an increased filtered bicarbonate load by increasing net LOH bicarbonate transport. In this setting, at the molecular level, mRNA and protein abundance of NHE3 were also stimulated, and coincided with an increase in NHE3 activity. Finally, NHE3 expression and abundance was highly stimulated in the early phase of diabetes, which is characterized by increased glomerular filtration rate (GFR).

Blood pressure and progression of renal failure in the elderly.

There are a lack of studies about elderly patients with chronic renal failure (CRF). We studied 22 patients, aged 64 to 74 years, who were diagnosed with hypertensive nephropathy (HN), defined as a diastolic blood pressure (DBP) < 95 mm Hg and a basal creatinine clearance (CCr) of 52 +/- 6 ml/min/1.73 m2. During the minimum two-year follow-up, the progression of renal failure (RF) was analyzed by the plotted slope of CCr versus time. Patients were divided into two groups, each administered one of two different drugs, Ca antagonists (group I) and angiotensin converting enzyme (ACE) inhibitors (group II). The DBP in both groups was lowered by the end of the study. The mean arterial pressure (MAP) was less in group I (97.35 +/- 5.98 mm Hg) than in group II (108.3 +/- 9.95 mm Hg). The decline in renal function was a mean rate of -0.62 +/- 0.36 ml/min/month in group I and -1.03 +/- 0.17 ml/min/month in group II. In conclusion, we show that patients who were on ACE inhibitors exhibited a greater MAP and a greater decline in renal function compared with the patients who were on Ca antagonist therapy. We also found that patients who were younger than 70 years old had better control of their blood pressure rates and less of a rate of decline in renal function than their older counterparts.

Histidine for treatment of uraemic anaemia.

A group of 28 uraemic patients on dialysis treatment were given daily supplements of histidine by mouth. Plasma amino-acid concentration, plasma iron, serum transferrin, packed cell volume, and reticulocyte count were all measured before and after two months of histidine supplementation. The treatment raised the plasma histidine concentration and at the same time there was a rise in transferrin and iron levels and packed cell volume. Reticulocyte counts fell after two months of histidine supplementation.