Effect of hydratation on renal water and sodium excretion in patients with renal arterial stenosis (S) and essential hypertension (EH).

Water and electrolyte excretion after a large water load and a small Na load was studied in a group of healthy volunteers (C) and in patients with renal arterial stenosis (S) and essential hypertension (EH). It was found that both groups of hypertensive patients reacted to this stimulus by higher Na, Cl, Ca and Mg excretion tan group C. In the two hypertension groups, cumulative Na excretion was comparable in size, but cumulative water excretion was significantly greater in group EH than in group S. The results indicate that these differences can be attributed to different localization of reduced Na reabsorption in the nephron. Signs of a decrease in Na resorption were found in the distal part of the nephron in both hypertension groups, but in the EH group they were also found in the proximal part.

Changes in circadian sodium excretion in patients with essential hypertension and with renal artery stenosis.

In groups of healthy volunteers (C), patients with essential hypertension (EH), and patients with renal arterial stenosis (S), the following indicators were followed during 12-hour daytime (d) and nighttime (n) intervals: mean BP, endogenous creatinine clearance Ccr (GF), excretion of sodium (UNaV) and potassium (UKV), and their excretion fractions (CNa/GF and CK/GF). The d/n ratios of both UNaV and CNa/GF were significantly lowered in both groups of hypertensive persons as against the controls (1.5): in the EH, to 1.1, and in the S, to 0.8 on the average. Positively correlated with the value of the d/n ratio of the sodium excretion are the changes in the d/n ratios of water and solute excretions. The daytime potassium excretion exceeded the nighttime values in both groups of hypertensive persons. The d/n ratios of UKV and CK/GF were, however, significantly lowered as compared to the control values. These signs of disturbances of the circadian excretion of Na and K in EH and S exhibited no correlations with the values, or rhythms, of the mean BP, GF, or dietary uptake of sodium. The results do not indicate that the antihypertensive drugs used (alpha-methyldopa, dihydralazine, reserpine) would influence the circadian rhythm of Na excretion. The factors responsible for the disturbances of the circadian rhythms of Na and K excretion in hypertensive subjects have not yet been revealed.