The role of renal proximal tubule transport in the regulation of blood pressure

The electrogenic sodium/bicarbonate cotransporter 1 (NBCe1) on the basolateral side of the renal proximal tubule plays a pivotal role in systemic acid-base homeostasis. Mutations in the gene encoding NBCe1 cause severe proximal renal tubular acidosis accompanied by other extrarenal symptoms. The proximal tubule reabsorbs most of the sodium filtered in the glomerulus, contributing to the regulation of plasma volume and blood pressure. NBCe1 and other sodium transporters in the proximal tubule are regulated by hormones, such as angiotensin II and insulin. Angiotensin II is probably the most important stimulator of sodium reabsorption. Proximal tubule AT(1A) receptor is crucial for the systemic pressor effect of angiotensin II. In rodents and rabbits, the effect on proximal tubule NBCe1 is biphasic; at low concentration, angiotensin II stimulates NBCe1 via PKC/cAMP/ERK, whereas at high concentration, it inhibits NBCe1 via NO/cGMP/cGKII. In contrast, in human proximal tubule, angiotensin II has a dose-dependent monophasic stimulatory effect via NO/cGMP/ERK. Insulin stimulates the proximal tubule sodium transport, which is IRS2-dependent. We found that in insulin resistance and overt diabetic nephropathy, stimulatory effect of insulin on proximal tubule transport was preserved. Our results suggest that the preserved stimulation of the proximal tubule enhances sodium reabsorption, contributing to the pathogenesis of hypertension with metabolic syndrome. We describe recent findings regarding the role of proximal tubule transport in the regulation of blood pressure, focusing on the effects of angiotensin II and insulin.

Agricultural accidents in a flammulina velutipes culture / 日本農村医学会雑誌

Flammulina velutipes culture is a flourishing agriculture in Nakano city. People who are 7.5% in all family are employed in flammulina velutipes culture. They use many kinds of machines therefor occasionally they are injured by them. We pick up the patients who were involved in agricultural accidents from 1978 to 1987 and analyzed statistically.<BR>Results obtained are as follows.<BR>1. Patients in accidents of flammulina velutipes culture account for 40% in all agricultual accidents.<BR>2. The compression machine's accident is a lot of the cause of flammulina velutipes culture's accident.<BR>3. The agricultural accidents appeared chiefly in 40 years and 50 years persons.<BR>4. The accidents were observed most frequently in winter-season, but rare in summer-season.<BR>5. The hand injuries are 90% in all part of injuries, rt. hand is 65% in hand jnjuries.