Stephen J. Walter

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1. The mechanism of the antidiuretic effect of hydrochlorothiazide in diabetes insipidus was studied in anaesthetized Brattleboro rats with the hereditary hypothalamic form of the disease. 2. The antidiuresis caused by acute administration of hydrochlorothiazide followed an increase in sodium excretion and was associated with a significant fall in the(More)
The validity of the lithium clearance technique as a measure of end-proximal fluid delivery was assessed using micropuncture in sodium-replete, Inactin-anesthetized Sprague-Dawley rats. Three groups of animals were used: controls, amiloride treated, and furosemide treated. Diuretic-induced salt and water losses were replaced. Fractional lithium excretion(More)
1. Renal function in anaesthetized Brattleboro rats with hereditary hypothalamic diabetes insipidus was studied with micropuncture techniques before, and 1-3 h after, a single injection of hydrochlorothiazide. 2. In rats given hydrochlorothiazide and kept in sodium and water balance, total glomerular filtration rate and superficial nephron filtration rate(More)
1. The marked reduction in fractional lithium excretion (FELi) which accompanies chronic sodium depletion was investigated using free-flow micropuncture in anaesthetized rats which had been maintained in a sodium-depleted state for 8-10 days. 2. Compared with previous values in sodium-replete rats, sodium depletion was associated with small reductions in(More)
1. Brattleboro rats with hereditary diabetes insipidus were maintained in metabolism cages for 12-14 days. During the final 5-7 days hydrochlorothiazide was added to the food of half the animals, resulting in a sustained antidiuresis. At the end of this time all rats were anaesthetized and their renal function was investigated. 2. Water, sodium and(More)
1. In order to identify the tubular sites responsible for the reduced fractional excretion of lithium (FELi) during potassium depletion, free-flow micropuncture was performed in anaesthetized rats that had been fed a low potassium (low-K+) diet or a control diet for 5-6 days. FELi in low-K+ rats was 0.09 +/- 0.02, compared with 0.25 +/- 0.01 in control(More)
1. Inulin clearance and lithium clearance (used as a marker of end-proximal fluid delivery) were measured in unrestrained conscious rats without the use of catheters. Lithium was added to the food and [14C]inulin was administered via an osmotic minipump implanted in the peritoneal cavity; blood was sampled from the tail. 2. Urinary excretion rates and body(More)
BACKGROUND Although it is known that moderate-to-high doses of the neurohypophysial hormones oxytocin and vasopressin are natriuretic, doubts remain over the identity of the receptors responsible. To address this issue, we have used highly selective antagonists of oxytocin and vasopressin receptors in animals with elevated endogenous circulating levels of(More)
The cardiovascular effects of an acute haemorrhage (2% of the body weight) were studied over a 60 min period in three groups of rats: (a) Brattleboro rats with hereditary hypothalamic diabetes insipidus (b.d.i.) lacking circulating vasopressin, (b) control rats of the parent Long Evans (l.e.) strain, and (c) l.e. rats treated with an antagonist of the(More)
The renal effects of glibenclamide were investigated using free flow micropuncture techniques in anesthetized Sprague-Dawley rats. Intravenous infusion of the drug (3 mg/hr) evoked a natriuresis and diuresis; potassium excretion remained unchanged. Fractional reabsorption in the proximal convoluted tubule in glibenclamide-infused rats did not differ(More)