Bartter's syndrome--observations on the pathophysiology.

The pathophysiology of Bartter's syndrome affecting seven adults has been investigated. (1) Saralasin infusion caused a fall in blood pressure in all patients, suggesting that angiotensin was contributing to the maintenance of blood pressure. (2) Following a water load, urinary chloride concentrations and osmolality were both low. No positive evidence for a defect in chloride reabsorption in the ascending limb of the loop of Henle was obtained. (3) The effect of high and low dietary sodium on plasma sodium, potassium, chloride, magnesium, renin activity, aldosterone, 6-keto-PGF1a, thromboxane B2, urinary kallikrein, platelet function and erythrocyte membrane cation transport were studied. A variety of responses was observed. Sodium restriction increased (or sodium loading decreased), plasma renin activity, aldosterone, 6-keto-PGF1a, urinary kallikrein and the platelet aggregation abnormality in some, but not all, individuals. (4) Treatment with indomethacin was undertaken in all patients and studied in detail in one patient. There was weight gain, increase in plasma sodium and potassium, decrease in capillary pH, positive sodium and potassium balance, and decrease in plasma renin activity, 6-keto-PGF1a, thromboxane B2 and urinary kallikrein. Hypomagnesaemia and excessive urinary magnesium loss persisted unchanged. (5) A variety of abnormalities of erythrocyte membrane cation transport was found and these persisted during high- and low-sodium, and high-potassium intakes; and during treatment with indomethacin, despite correction of intracellular sodium and potassium concentrations. Bartter's syndrome is associated with an abnormality of erythrocyte membrane sodium and potassium transport. Many of the other metabolic abnormalities may be the consequence of potassium and sodium depletion.