Catherine S. Delea

The effect of high-sodium and low-sodium intakes on blood pressure and other related variables in human subjects with idiopathic hypertension

Nineteen patients with hypertension in whom all known causes of blood pressure elevation had been ruled out were classified as salt-sensitive or nonsalt-sensitive from the changes in blood pressure with changes in sodium intake from 9 meq to 249 meq/day. With the diet containing 249 meq sodium per day, there were no statistically significant differences in plasma sodium, potassium, chloride, aldosterone, cortisol or renin activity, or in urinary potassium, aldosterone or 17-hydroxycorticosteroids between the two groups. The salt-sensitive patients retained more sodium on the high-sodium diet than did the patients who were not sensitive to salt (nonsalt-sensitive); accordingly, sodium induced more weight gain in the salt-sensitive patients.

Factors influencing blood pressure in salt-sensitive patients with hypertension

Abstract Eighteen patients with hypertension in whom all known causes of elevated blood pressure levels had been ruled out were studied during a low-sodium diet for seven days, a high-sodium diet for seven days and after the oral administration of furosemide. They were classified as salt-sensitive (SS) or nonsalt-sensitive (NSS) from the increase in 24-hour averages of mean blood pressure with changes in sodium intake from 9 meq to 249 meq/day (15.1 ± 1.2 (SE) mm Hg (SS) versus 2.7 ± 0.9 mm Hg (NSS), (p 2 (PGE 2 ) which decreased (p 2 , whereas NSS patients showed increases (p

Successful treatment of recurrent nephrolithiasis (calcium stones) with cellulose phosphate.

Abstract Sixteen patients with absorptive hypercalciuria and nephrolithiasis ate a low-calcium diet and were given cellulose phosphate (5 g twice to three times per day orally). In all 16 cases urinary calcium decreased, usually to values below 200 mg per day, and in 13 cases, the state of saturation of urine with respect to brushite (the nidus of calcium stones) also decreased, often from supersaturation to undersaturation. Clinically, renal-stone formation virtually ceased. The treatment was well tolerated, and no serious side effects have been observed. Serum concentration of parathyroid hormone and bone density by 125I-photon absorption did not change significantly or remained within the normal range. Thus, in these patients with an enhanced intestinal absorption of calcium, hypercalciuria may be corrected, and stone formation prevented, by a low-calcium diet and inhibition of calcium absorption with cellulose phosphate. (N Engl J Med 290:175–180, 1974)

Arterial Sodium Content in Experimental Congestive Heart Failure

This study sought to determine whether the electrolyte content of peripheral arteries is altered in experimental congestive heart failure (CHF) and whether such change, if present, would help to explain the abnormal vascular stiffness seen in human CHF. The concentrations of sodium (Na+) and potassium (K+) were determined in samples of aorta (Ao) and femoral arterial branches (FA) of 17 dogs. Six had ascites due to CHF produced by rapid ventricular pacing (left ventricular end-diastolic pressure [LVEDP] 26.2 mm Hg and maximal velocity of myocardial shortening [Vmax] 2.39 circumferences/sec). In the 11 animals in the control group pacing was stopped prior to the onset of CHF or the animals were not paced (LVEDP, 8.8 mm Hg and Vmax, 2.98 circumferences/sec). In CHF, mean Ao Na+ was 38.0 ± 2.3 mEq/100 g dry weight and FA Na+ was 44.2 ± 3.2 mEq/100 g. These were significantly higher than similar samples taken from the 11 normal dogs (Na+, 31.9 ± 1.6 [P < 0.05] and 31.9 ± 1.8 [P < 0.01] mEq/100 g, respectively...

A MAP OF BLOOD AND URINARY CHANGES RELATED TO CIRCADIAN VARIATIONS IN ADRENAL CORTICAL FUNCTION IN NORMAL SUBJECTS

I t is well known that many physiological functions exhibit 24-hour or approximately 24-hour (circadian) periodicity.* It is not clear what relationship the temporal phase within the day for each of these variables bears to that of the others, or the extent to which this relationship is a fixed one. This relationship has been termed “internal t The numbers of circulating leukocytes and the urinary excretion of water and salt and of adrenal corticosteroids and their metabolites are known to manifest such periodicity in normal subjectse6-11 The present study was designed to obtain data on a relatively homogeneous group of normal subjects so that a circadian “map” may be constructed for blood and urinary changes known or thought to be related to cyclic changes in adrenal function. Such a map should serve three purposes: (1) i t should aid in the design of physiological experiments so that changes resulting from a treatment may be clearly distinguished from those resulting from spontaneous fluctuations;12 (2) temporal relationships between maxima and minima for different variables may provide valuable information as to whether one physiological event may or may not be dependent on another; and (3) such a map may provide temporal reference standards that allow better definition of disease states. Thus, if the periodic change in a given function is dependent on periodic change in the secretion of an endocrine gland, evidence of an absence of such fluctuation may be of aid diagnostically in establishing non-function, or continuous non-fluctuating (or unpredictably fluctuating) overfunction of the gland. When in either case the secretion of the gland loses its circadian periodicity, a map of other variables may serve to define which of them owes its rhythmic behavior to the cyclic behavior of the gland in question.

Chronobiology of blood pressure.

Blood pressure in normal and hypertensive subjects shows circadian variability with the minima during the hours of sleep. The factors influencing blood pressure show circadian variability, in particular, plasma and urinary aldosterone, plasma deoxycorticosterone and urinary sodium (factors implicated in cardiac output), angiotensin II as measured by plasma renin activity, plasma and urinary epinephrine and norepinephrine, and plasma and urinary prostaglandins of the E series (factors implicated in peripheral resistance). Direct causal relationships have not been established. The treatment of hypertensive subjects in relation to the circadian variability is reviewed.

The treatment of osteoporosis with calcium infusions: Clinical studies

Abstract An increase in the serum calcium (Ca) concentration normally suppresses parathyroid function and stimulates the secretion of thyrocalcitonin. Hypercalcemia resulting from intravenous administration of Ca should therefore lead to a net retention of Ca. This hypothesis was tested in six patients with osteoporosis. After twelve Ca infusions, four patients showed clinical improvement, net Ca retention, enhanced bone formation and reduced bone resorption and an increase in the gastrointestinal absorption of Ca. These effects persisted for many months after Ca infusions were stopped. If calcium given in this way leads to a prolonged suppression of parathyroid function and a comparably enhanced stimulation of thyrocalcitonin secretion, it may reverse the metabolic errors that constitute osteoporosis.

Control of calcium absorption: Effect of sodium chloride loading and depletion

In six out of eight patients with normal parathyroid function and in two subjects with hypoparathyroidism, sodium chloride loading was shown to increase calcium absorption as measured by the 47Ca absorption test. Although no significant change was seen in the renal and fecal excretion of calcium, a slight decrease in total serum calcium did occur with increased sodium intake. The change in calcium absorption was not accompanied by a detectable change in calcium balance. Therefore, a compensatory change in gastrointestinal calcium secretion must have occurred. Sodium intake has an effect on calcium in the gastrointestinal tract, which is independent of parathyroid hormone. Sodium intake should be considered when results of studies of calcium metabolism are compared.

Neurodegenerative disorders and hyperaldosteronism.

Elevated plasma renin (3 patients) and aldosterone secretion rates (4 patients) have been found in patients with the syndrome of “ophthalmoplegia plus.” Autopsy in one of the patients revealed subacute necrotizing encephalopathy, hyperplasia of the juxtaglomerular apparatus, and nodular hyperplasia of the zona glomerulosa of the adrenal gland. Three of the patients had hypokalemia during the present admission and the fourth patient had hypokalemia in the past. Two of the patients also had hypomagnesemia. Spironolactone given to one patient corrected the hypokalemia but had no effect on the hypomagnesemia. It is suggested that hyperaldosteronism should be looked for in patients with the syndrome of “ophthalmoplegia plus”.

Idiopathic edema: II. Pathogenesis of edema in patients with hypoalbuminemia

Abstract Patients with idiopathic edema, previously shown to have a significantly subnormal total circulating albumin level and a significantly subnormal plasma volume, were found to have abnormally large amounts of the neurohumoral transmitter norepinephrine in the urine, an abnormally high plasma renin activity when supine which increased still further when they assumed the upright posture, and hypersecretion of aldosterone. The subnormal plasma volume and the increase in adrenergic activity apparently produced thereby, presumably increased plasma renin activity and, in turn, the secretion of aldosterone. An increase in adrenergic discharge to the kidney and an increase in circulating aldosterone can both increase the reabsorption of sodium by the renal tubules and could therefore be the basis for the excessive sodium retention and edema which is characteristic of these patients.