O. Hall

Comparative Effectiveness of Glucose and Sucrose in Enhancement of Hypersalimentation and Salt Hypertension.

Summary The quantity of 1% saline consumed and the development of salt hypertension in rats were comparably enhanced by addition of either glucose or sucrose in 5% concentration to the drinking solution. Cardiac hypertrophy and lesions were equivalently increased. A curious, and as yet unexplained finding, is that whereas kidney enlargement accompanied consumption of either saline or sucrose-saline solution, such was not the case with glucose-saline. Here the kidney weight did not exceed that of controls, and reno-vascular lesions although present were less pronounced than when other saline solutions were drunk.

Immunity of Fischer 344 rats to salt hypertension

Abstract Female Fischer 344 rats sensitized to the development of salt hypertension by unilateral nephrectomy were given water, 1% NaCl solution or 5% sucrose + 1% NaCl solution to drink. Rats on saline alone drank about twice the fluid volume of those on water, whereas those on the sucrose-saline solution drank four to six times as much. No Fischer 344 rats ever developed hypertension, defined as a systolic pressure exceeding 150 mm Hg, during the six months of the study. However, the group on saline averaged slightly higher arterial pressures than those on water on 13 of the 14 occasions that blood pressure was measured, and the average pressure over the entire experimental period was also significantly increased. The rats on sucrose-saline had a group mean blood pressure which was always significantly higher than that of the group on water and usually greater also than that of the group on saline, and the average pressure over the entire experimental period was significantly augmented above that in either of the other groups. Rats on either of the saline solutions also had a slight but significant degree of heart and kidney enlargement, greatest in the sucrose-saline group, which is attributed to the higher pressures developed, even though they remained within the normotensive range.

Polyvinyl Alcohol Nephrosis Relationship of Degree of Polymerization to Pathophysiologic Effects.

Summary Polyvinyl alcohol of 3 different molecular weights, 37,000, 133,000 and 185,-000, was injected daily and subcutaneously into rats on a high NaCl intake. The lowest molecular weight material was not demonstrated in any of the tissues examined and, over the period studied, produced only mild elevation of blood pressure in a third of the animals which received it. High molecular weight PVA infiltrated a number of organs and tissues. Most prominently it affected renal glomeruli causing swelling and multiplication of endothelial and epithelial cells and often crescent formation. Mild hypertension affected half of the animals and heart, kidneys, liver and spleen were enlarged. Neither polymer caused polydipsia. The intermediate polymer produced severe polydipsia, a nephrotic syndrome associated with ascites and edema, severe hypertension, marked renal damage with severe glomerulonephritis, often hemorrhagic, and widespread cardiovascular lesions. The pathologic effects depend more upon the molecular size than upon chemical structure.

Resistance of Fischer 344 rats to deoxycorticosterone hypertension

Abstract Implantation of one 40 mg pellet of DOCA causes hypertension in the majority of young female Sprague-Dawley rats within three weeks without removal of a kidney or adding salt to the diet. Similar identically-treated Fischer 344 rats remain normotensive. If one kidney is removed and 1% saline is given to drink, the hormone dosage causes hypertension in rats of both strains, although even here Fischer 344 rats develop the disorder more slowly and less severely. It is concluded that for rat strains resistant to mineralocorticoid hypertension, sensitization is necessary for its induction, whereas for susceptible strains it is not. Fischer 344 rats appear to have higher levels of resting serum renin activity than Sprague-Dawley rats, but the relationship that this bears to hypertension susceptibility is unknown.

Persistence of desoxycorticosterone-induced hypertension in the nephrectomized rat.

Summary The blood pressure of rats rendered hypertensive by treatment with desoxycorticosterone acetate continues to rise following total nephrectomy. Hypertension of this type is not dependent upon a renal mechanism for its maintenance and it is not a. consequence of renal vascular damage which is a later development. The relationship of the adrenal cortex to certain forms of clinical hypertension is discussed.

Growth effects of desoxycorticosterone and cortisone with special reference to compensatory renal hypertrophy.

Summary 1. In a dosage of 2 mg/day cortisone completely halted body growth and produced adrenal atrophy and slight cardiac hypertrophy. Kidney size in intact cortisone-treated rats increased by 25% which, since it occurred in the absence of an increase in body weight, resulted in kidneys which were disproportionately large in relation to body size. 2. Doca in the same dosage was without effect on body weight or heart weight. Slight adrenal atrophy and moderate enlargement of the kidneys in intact animals was observed. 3. Compensatory renal hypertrophy was greatest in controls and diminished to the same extent by either Doca or cortisone. It was suppressed to the greatest extent, but not completely prevented, by a restriction of food intake to a level permitting only maintenance of a static body weight.

Comparative ability of certain sugars and honey to enhance saline polydipsia and salt hypertension.

Summary Sucrose, maltose, fructose and honey, each at a 5% concentration in 1% sodium chloride solution used as drinking fluid, were compared in respect to their ability to influence saline consumption and the development of arterial hypertension. Honey was without detectable effect on either of these. The pure sugars, in the order of increasing effectiveness fell into the order sequence fructose, maltose and sucrose. Only sucrose significantly increased consumption of saline throughout the experiment, and was unquestionably the most effective carbohydrate in promoting saline ingestion and in enhancing salt hypertension. The data available from several sources indicate that it is neither sweetness, as the term is commonly understood, nor the calorie value which endows certain sugar solutions with the appeal they have for rats.

INCREASED SENSITIVITY TO X-IRRADIATION EXHIBITED BY STRESSED RATS

Electroshock stress applied prior to x irradiation does not affect survival or survival rate of rats exposed to 640 r, whereas if applied efterward it decreases both. Stress incurred by rats during shipment to the laboratory, followed shortly by irradiation, reduces their survival and increases montality rate. Variations in the duration and intensity of stress incident to the handling of animals in order to irra diate them might well contribute to the severity of injury sustained. This could account, in pad, for variations in survival rate and survival from group to group at the LD/sub 50/ level as reported by others and noted. The stresses used in this study were limited to a relatively brief period either pre- or postirradiation. In this way biologic exhaustion and biologic adaptation were minimized. This is in contrast to most studies, in which stress has either been applied for weeks or months, before or after x irradiation, or has been imposed to a degree which left the subjects in a state of exhaustion. (auth)

Endocrine factors affecting weight and ascorbic acid content of rat preputial glands.

Summary 1. The normal level of ascorbic acid in the preputial glands of the young male rat is 60 mg %. 2. Adrenalectomy (3 wks) induces preputial gland hypertrophy, which is partially prevented by DCA. 3. Severe stress produces a depletion of preputial ascorbic acid, which is accentuated in hypothyroid animals. 4. Hypophysectomized rats (24 hr) have a level of preputial ascorbic acid which is 78% that of controls.

Sodium excretory response to acute salt loading and induction of adrenal-regeneration hypertension in Fischer 344 rats.

Abstract Previous studies have shown Fischer 344 rats to be extremely resistant, if not immune to the development of salt hypertension. This is true even under the severe experimental conditions that overcome the very low susceptability of other strains such as the Long-Evans. These studies were confirmatory and also showed that the resistance could not be attributed to the ability of Fischer 344 rats to excrete salt more effectively than hypertension-prone SPD animals. Fischer 344 rats are normally susceptible to adrenal-regeneration, and not resistant to hypertension as such. Certain attributes and characteristics of strains showing resistance to salt hypertension are compared and contrasted.