Cellular sodium concentration and vasoconstrictor state in hypertension

The sodium content of peripheral blood leucocytes was estimated in two separate investigations of the relationship between cellular sodium content and the vasoconstrictor state. In the first study various parameters of forearm blood flow were measured in a group of 31 normal subjects. A positive correlation was found between peripheral vascular resistance and leucocyte sodium content (p less than 0.05), and a negative correlation between venous compliance (VV60) and leucocyte sodium content (p less than 0.001). In the second study the leucocyte sodium content of 14 patients with essential hypertension was investigated before and after treatment with the calcium antagonist verapamil. The sodium content was found to be abnormally high, as previously described, and treatment with verapamil was found to reverse the defect. Both studies indicate a link between cell sodium content and the vasoconstrictor state, and the results are discussed in light of current theory.

Does potassium lower blood pressure by increasing sodium excretion? A metabolic study in patients with mild to moderate essential hypertension

Potassium chloride (96 mmol potassium/day) in the form of 12 Slow K tablets/day in 10 patients on an intake of 150 mmol sodium and 80 mmol potassium produced a cumulative sodium loss of 110 mmol by the 12th day of potassium supplementation. At the same time there was attenuation of the expected increase in plasma renin activity appropriate for such a sodium loss. The lack of rise in plasma renin activity and hence angiotensin II combined with sodium loss may account at least in part for the observed blood pressure fall. No change in ouabain-sensitive or total white cell sodium efflux rate constant was found. An effect of an increase in plasma potassium on the sodium pump cannot be excluded as the white cell sodium efflux rate constant was measured in a fixed external potassium concentration. There was no evidence from plasma noradrenaline measurements that increasing potassium intake reduces sympathetic activity in the resting state.

Recovery of renal function after prolonged dialysis and transplantation

Out of 250 patients with renal failure, seven (2.8%) treated by regular haemodialysis alone (four) or given cadaveric allografts (three) later showed recovery of function of their own kidneys lasting from one to four years. In the patients receiving haemodialysis alone recovery was easily recognised from their serum creatinine concentrations, but in those with transplants recovery was discovered unexpectedly during radionuclide scanning. These findings suggest that recovery of renal function may be more common than generally recognised, which should be borne in mind when beginning renal replacement treatment and particularly when contemplating bilateral nephrectomy.

Reversible renal failure due to captopril in a patient with transplant artery stenosis. Case report

A patient who was subsequently shown to have stenosis of the artery to a transplanted kidney sustained three episodes of impaired renal function during treatment with low doses of captopril. On each occasion this was reversed by withdrawal of therapy. The effect was not related to reduction of blood pressure since lower pressures were recorded during treatment with minoxidil, without deterioration of renal function. A possible mechanism involving blockade of the intrarenal renin-angiotensin system is discussed.

The effects of alterations in the external sodium concentration on human leucocyte sodium and potassium transport in vitro

Human leucocytes incubated in tissue culture fluid of low-sodium concentration (2 mM; iso-osmolarity maintained with choline chloride) reached a new equilibrium within 1 hour and lost approximately 25% of intracellular potassium and 70% of intracellular sodium. The rate constant for ouabain-sensitive sodium efflux fell by more than 50% and the ouabain-insensitive rate constant increased nearly threefold in the low-sodium medium. Total sodium efflux fell in proportion to internal sodium whereas ouabain-insensitive sodium efflux remained unchanged. A reduction in external sodium from 140 to 2 mM was associated with a 75% fall in sodium influx. In the low-sodium medium ouabain-sensitive potassium influx exceeded ouabain-sensitive sodium efflux and no ouabain-sensitive potassium efflux could be demonstrated. Ouabain-insensitive potassium influx and that portion of potassium efflux which is dependent on external potassium fell in parallel in low-sodium cells, suggesting reduced activity of a ouabain-insensitive K:K exchange system.

Increased sodium content and altered sodium transport in thymocytes of spontaneously hypertensive rats

1. The intracellular sodium content and the sodium efflux rate constant have been determined in vitro in thymocytes derived from the Okamato-Aoki strain of spontaneously hypertensive rats. 2. A strong positive correlation between the systolic blood pressure and the sodium content of thymocytes was observed (r = 0.59, n = 39, P less than 0.001). 3. The rate constant for total sodium efflux was negatively correlated with systolic blood pressure (r = -0.43, n = 45, P less than 0.005) and this was due to a fall in the ouabain-sensitive component of sodium efflux. 4. Sodium efflux, influx and the thymocyte potassium content were not related to the blood pressure.

Effect of extracellular potassium on the transport of sodium and potassium in rat thymocytes

1. The effect of extracellular potassium on the transport of sodium and potassium in rat thymocytes has been studied in vitro. 2. A significant increase in the rate constant for total and ouabain-sensitive sodium efflux was demonstrated at an extracellular potassium concentration of 1 mmol/l as compared with that at either 0 or 2 mmol/l. 3. At potassium concentrations below 3 mmol/l ouabain-sensitive sodium influx was observed suggesting sodium-sodium exchange catalysed by the sodium pump. 4. Both total and ouabain-insensitive potassium efflux rose with external potassium. A small ouabain-sensitive potassium efflux was observed at all levels of external potassium studied. 5. Total and ouabain-insensitive potassium influx increased with external potassium, but did not appear to saturate. Ouabain-sensitive potassium influx reached a maximum at an external potassium concentration of 2 mmol/l then decreased with increasing external potassium.

The relationship between leucocyte and muscle zinc in health and disease

1. A significant correlation between leucocyte and muscle zinc contents was observed in control patients and in patients with generalized diseases. 2. As muscle contains a large proportion of the whole-body zinc, it is suggested that leucocyte zinc content may be a useful indicator of tissue zinc status.

The effect of antihypertensive therapy on abnormal leucocyte sodium transport in essential hypertension

Sodium transport in leucocytes of essential hypertensives was studied in physiological media. Untreated hypertensives have depressed values for the total and ouabain-sensitive sodium efflux rate constant. Treatment with diuretics abolished this abnormality. These results are compatible with the presence of a circulating inhibitor of sodium transport in essential hypertension.

Zinc transport in normal human leucocytes: dependence upon media composition

1. The transport of zinc has been studied in normal human leucocytes incubated in both a tissue culture medium and Krebs buffer. 2. 65Zn influx is characterized by an initial rapid phase followed by a slower influx. 65Zn influx is directly dependent upon the extracellular zinc concentration. 3. Net zinc influx could only be demonstrated in Krebs buffer at zinc concentrations in excess of 4.3 mumol/l and in tissue culture fluid at zinc concentrations in excess of 43.1 mumol/l. 4. A 65Zn efflux rate constant of approximately 1.0 per h was observed in both 4.3 and 15.4 mumol of zinc/l of Krebs buffer or tissue culture fluid. 5. In a zero external zinc Krebs buffer the 65Zn efflux rate constant fell to 0.57 per h and was accompanied by a small net zinc efflux.

Reversible renal failure in malignant hypertension

Acute renal failure requiring dialysis to sustain life may be due to malignant hypertension. If the blood pressure is controlled during a period of dialysis, then it is possible that the renal lesions may heal, with some recovery of renal function. This report describes eight patients with acute renal failure due to malignant hypertension who required temporary dialysis. In all eight cases adequate control of blood pressure was achieved and all recovered renal function such that dialysis could be discontinued. The longest period of follow-up was five years, and one patient achieved a creatinine clearance of 23 ml/min. Renal histology, available in five cases, showed changes of malignant hypertension only, with no evidence of other renal lesions. A review of the literature is presented and the potentially reversible nature of acute oliguric renal failure due to malignant hypertension is emphasized.

Reduced leucocyte zinc in liver disease

The zinc content of peripheral blood leucocytes has been measured in normal controls and in three groups of patients with liver disease. A significant reduction in leucocyte zinc, but not erythrocyte zinc, was observed in patients with primary biliary cirrhosis, alcoholic cirrhosis, and active chronic hepatitis. It is suggested that the nucleated tissues of some patients with liver disease are therefore zinc deficient, and that leucocyte zinc may prove of value in the assessment of the zinc status of such patients.

Effect of acid-base changes on the intracellular sodium, potassium and water content of human leucocytes in vitro

1. Leucocytes were isolated from blood of healthy volunteer subjects and incubated in media of which the bicarbonate, PCO2 and pH composition were varied. 2. The intracellular sodium, potassium and water content of leucocytes were virtually unaffected by the acid-base composition of the media used.