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Electrolytic lesion of the medio-ventral septal (MVS) area produces, 3 days after the surgery, a remarkable increase of daily diuresis and water intake in the rat. This polyuria and polydipsia is associated with decreased levels of circulating radioimmunoassayable vasopressin. In addition, if these lesioned animals were water-deprived (48 h), the usual vasopressin release observed in sham-lesioned and normal controls was markedly blunted. These results suggest that the MVS area exerts a modulatory control on vasopressin secretion both in basal and thirst-evoked conditions.

A metabolic study was performed in 28 patients with bilateral recurrent calcium-containing renal staghorn calculi and chronic pyelonephritis ("obstructive nephropathy"). Fourteen had normal GFR and 14 mild renal insufficiency. Ten normal subjects were used as controls. Under basal conditions, polyuria and negative sodium balance were commonly observed in patients with obstructive nephropathy and normal renal function. After an acute acid load (NH4Cl) an acidifying defect, i.e. high values for urine pH and reduced excretion of titratable acid and ammonium, was observed in 64% of patients with normal GFR and in 71.4% of those with renal insufficiency. During intravenous infusion with neutral sodium phosphate, the urine pH changed little but the rate of excretion of titratable acid increased in direct proportion to that of urinary phosphate in both groups of patients. These results, associated with the finding of normal blood pH in almost all patients, lead to the conclusion that an incomplete Type 1 or "distal" renal tubular acidosis is a frequent complication of obstructive nephropathy secondary to bilateral nephrolithiasis. The anatomical abnormalities of renal tubules and collecting ducts and the superimposed interstitial nephritis might be the pathogenetic factors responsible for the acidifying defect and for the impairment in sodium and water conservation.

In two dogs with pituitary-dependent hyperadrenocorticism, adrenocorticolysis with o.p'-DDD led to the disappearance of the signs and symptoms except for the polyuria. After a modified water-deprivation test the osmoregulation of vasopressin release was studied by hypertonic saline infusion. In both dogs the hypertonicity, thus induced, resulted in very minimal responses of the vasopressin secretion.

From the analysis of several studies published from 1979 to 1986 comprising 1,172 patients, we estimated that glomerular filtration rate (GFR) was normal in 85% of unselected patients on chronic lithium therapy. The remaining 15% of patients displayed only mild reduction in GFR, clustering at approximately 60 mL/min. Thus, the data available to date do not support earlier concerns that long-term lithium therapy could eventuate into renal insufficiency. The most prevalent renal effect of lithium is impairment of concentrating ability, which we estimated to be present in at least 54% of 1,105 unselected patients on chronic lithium therapy. This defect translated into overt polyuria in only 19% of unselected cases. A renal lesion confined to the collecting tubule has been described in humans who have taken lithium for short periods of time. This lesion may represent the collecting tubule's response to the intracellular accumulation of lithium, which interferes with cAMP formation and results in an early and probably reversible inhibition of antidiuretic hormone (ADH)-mediated water transport. However, long-term lithium therapy may induce a progressive and partly irreversible defect in concentrating ability. The potential risk for dehydration associated with lithium-induced polyuria, as well as the discomfort inherent to this side effect, deserves evaluation and consideration for therapeutic intervention. Amiloride has additional advantages over conventional treatment of nephrogenic diabetes insipidus using thiazide diuretics. The action of amiloride on ADH-mediated water transport seems specific in as much as it is capable of preventing the uptake of lithium in high resistance epithelia and thereby prevents the inhibitory effect of intracellular lithium on water transport. Unlike thiazides, amiloride has a weak natriuretic effect and is less likely to increase plasma lithium levels by causing volume contraction. In addition, amiloride, by conserving potassium, obviates the need for potassium supplementation that is usually required to prevent hypokalemia when thiazides are used to treat lithium-induced polyuria. Since amiloride may prevent chronic intracellular lithium accumulation in the collecting tubule, future studies should elucidate whether amiloride also has a role in preventing lithium-induced chronic tubulo-interstitial damage.

These experiments were aimed at investigating renal behavior towards chloride, as distinct from sodium, during dietary deprivation of these ions in adrenalectomized rats. Adrenalectomized and shamoperated control rats were maintained on saline for 3 wk, then chloride conservation during a very low chloride intake was assessed both with an abundant sodium intake (as buffered sodium phosphate in the drinking water) and after subsequent withdrawal of sodium. When sodium intake was high, there was no difference in chloride conservation between adrenalectomized and control animals, and sodium balance and weight were maintained similarly in both groups. At the same time, both experimental and control rats developed significant hypokalemia and elevation of the plasma bicarbonate levels as compared to other control rats ingesting a normal diet. In another group of adrenalectomized rats sodium phosphate was withdrawn, after normal chloride conservation was observed, and the low-salt diet continued. Negative sodium balance developed and was associated with a negative chloride balance, whereas sham-operated rats continued to conserve sodium and chloride. In further studies during polyuria, both adrenalectomized and control rats developed urinary chloride concentrations of less than 1 meq/liter. Thus adrenalectomized rats can maintain chloride balance on a low chloride, high sodium intake, in contrast to their inability to conserve sodium on a low-sodium intake. It is concluded that renal tubular reabsorption of chloride in adrenalectomized rats is adequate to establish and maintain very low urinary chloride concentrations, which may imply active chloride transport in the papillary collecting duct despite the absence of adrenocortical hormone. In addition, the typical renal response to chloride deprivation, enhanced loss of potassium and accelerated reabsorption of bicarbonate, is not dependent on adrenocortical hormones.

A patient exhibited brain damage, polyuria, and refractory hypernatremia after myocardial infarction and cardiopulmonary arrest. Serum vasopressin levels were relatively fixed and inappropriately low for the elevated serum osmolality. Hypernatremia persisted despite administration of vasopressin; after vasopressin was discontinued, serum sodium value was corrected with small doses of furosemide and replacement of free water. In her case, impairment of osmotic homeostasis could not be attributed to either simple resetting or complete destruction of osmoreceptors; metabolic normalization required an unusual therapeutic approach.

We have experienced with 50 cases of parasellar tumors, four cases of which had persistent thirst, polydipsia, polyuria, and reversible temporary hyponatremia secondary to hypernatriuresis. The mechanism of the syndrome in these four cases could not be explained by either that of the syndrome of hypernatremia or of the so-called SIADH. We tentatively named this syndrome as "CEREBRAL POLYURIC HYPONATREMIA" and the criteria of this syndrome as as follows: 1) persistent thirst, polydipsia polyuria, 2) reversible temporary hyponatremia secondary to hypernatriuresis, 3) exception of the following items--administration of uretic drugs, renal and adrenal dysfunction, hyperglycemia, hyperlipemia, overadministration of water, and poor administration of NaCl. The mechanism of this syndrome is presumed as follows: 1) compression by a tumor or surgical attack to the anterior hypothalamus, 2) disturbance of the mechanism of ADH secret-on, 3) extrasecretion of natriuretic factor possibly produced in the anterior hypthalamus, and 4) preservation of the thirst center.

Renal, glomerular and tubular, factors responsible for the volume control of extracellular liquid were examined. The part played by angiotensin II in mediating the compensation of this liquid losses was studied in patients with spontaneous polyuria due to diencephalo-posthypophyseal diabetes insipidus or psychogenic polydipsia and healthy subjects with induced hypotonic polyuria. It was noted that: 1) acute expansion elicited a natriuretic response and increased distal sodium load, due to an increase in filtrate and relative inhibition of proximal reabsorption, or proximal inhibition if the filtrate was unchanged. The efficiency of distal sodium transport was often unchanged. 2) Return to sodium balance parity during prolonged expansion of volume, was accomplished by varying renal means, in accordance with the experimental model employed. Distal reabsorption was essentially depressed during prolonged saline load (secondary hypoaldosteronism). When protracted mineralcorticoid treatment was used, however, distal reabsorption was high, even in the escape stage, and its saturation required marked augmentation of the sodium load reaching the distal tubules. 3) Depletion of volume caused by protracted natriuretic treatment in spontaneous polyuria reduced both diuresis and sodium excretion. This resistance to the natriuretic effect of the drug followed intrarenal compensation that reduced the distal sodium load and encouraged reabsorption in some distal sites (secondary hyperaldosteronism). 4) Infusion of angiotensin II in sub- or pauci-pressor doses causes an isosmotic sodium saving, since it reduced the glomerular filtrate and increases the fraction of filtrate reabsorbed by the proximal tubules; the tubular effect is likely secondary to increased vascular, especially postglomerular resistance. In the healthy subject, angiotensin II leads to antidiuresis referable, on account of its intensity and longer time cycle, to ADH release angiotensin-dependent.

Polyuria subsequent to pituitary surgery was studied in 64 cases. Most cases of postoperative polyuria were due to diabetes insipidus. These cases showed a triphasic pattern in daily urinary volume. Observation of hourly urinary volume in polyuria revealed four diurnal patterns of urinary excretion: rhythmic, continuous, transient, and unspecific. Clinical observation of diurnal patterns has an advantage, in terms of simplicity of procedure, in immediately determining the nature of the polyuria, prognosticating diabetes insipidus, and eliminating inappropriate procedures in treatment. Indomethacin suppository is considered to be a favorable agent in reducing polyuria without disturbing the diurnal pattern in diabetes insipidus.

The effect of water deprivation on lithium clearance was studied in rats with lithium-induced polyuria. During a 3-hr period of water deprivation, the rats lost water in amounts corresponding to about 10% of body weight. Lithium clearance fell to about 25% of the level observed in rats which were not water deprived. During shorter periods of water deprivation, the fall of lithium clearance was less. The decrease of lithium clearance was partly due to a fall of inulin clearance and partly due to a fall of fractional excretion of lithium. The decrease of the two variables contributed to the same extent to the decrease of lithium clearance. The findings support the suggestion that insufficient intake of water in patients with lithium-induced polyuria may lead to a rapid lowering of lithium clearance and, hence, to a rise of the serum lithium concentration and development of intoxication.

Water balance studies were performed in 7 experimental dogs before and during a period of cortisol-induced polyuria and in one dog with spontaneous hyperadrenocorticism before and after removal of an adrenocortical carcinoma. Measurements of urine and plasma osmolality and plasma arginine vasopressin concentration were made at regular intervals during the water deprivation studies. The results indicate that cortisol does not block the release of vasopressin but interferes with its action in the kidney.

The role of renal tubules was explored by two kinds of experiments: (1) inhibition of the tubular reabsorption of insulin by induced polyuria; (2) suppression of insulin filtration by ureter clamping; 1. Anaesthetized dogs maintained in normoglycaemia by glucose compensation were infused with crystalline and 125I-insulins. Polyuria was induced by: (1) saline-bicarbonate infusion; (2) furosemide with saline-bicarbonate infusion to replace urine losses; (3) massive infusion of mannitol. Inulin and paraminohippuric acid were used to estimate the glomerular filtration rate and the renal plasma flow. The permeability of the glomerular wall (pore radius and total area of the pores per unit of path length) was determined by measuring the sieving curve of 131I-polyvinyl-pyrrolidone fractions during basal and treatment periods. Mannitol infusion was able to bring the insulin/inulin clearance ratio up the values of the sieving coefficient of insulin (insulin filtration rate) without modifying the permeability of the glomerular wall; saline infusion displayed a similar effect; furosemide, only a minute one although it induced a more marked polyuria. 2. Clamping of the left ureter was performed on dogs with catheters inserted into the artery, the left renal vein, the pelvis and a renal lymphatic vessel. Almost complete suppression of the glomerular filtration was achieved. It slightly increased the high insulinic concentration of the renal lymph, entailed a 1/3 decrease in the extraction ratio of insulin and reduced by half its renal clearance. In conclusion, the tubules participate to the catabolism of insulin by two different mechanisms: (1) an uptake from the tubular fluid which can be inhibited by diuretics exerting their main action on the proximal tubules; (2) a direct catabolism from the interstitial fluid resulting from the large permeability of the peritubular capillaries to insulin.