H. W. Hays

Hyperthyroidism and Liver Function in Relation to B Vitamins

Conclusions 1. Using a standard diet, with yeast of a known vitamin content, the liver functions of dogs was studied at two levels of thyroid feeding. 2. The production of the abnormal liver function in hyperthyroid dogs bears a causal relationship to the yeast in the diet.

Effect of Cortical Hormone upon Blood Pressure in Shock Induced by Massive Doses of Adrenalin

Previous work 1 led to the conclusion that cortical hormone exerts a direct effect upon the low blood pressure in shock induced by stripping the intestine. The pressor action of the hormone appeared to be more or less independent of serum electrolyte and associated blood volume changes. The present experiments on adrenalin shock lend further support to these conclusions. Five adrenalectomized dogs were used. They were active, vigorous, at peak weight and indistinguishable from intact animals. No hormone was administered 18 hours previous to use in the experiments. Table I shows that they had normal blood pressures, blood concentration and serum electrolytes. These dogs were given 20-40 cc. of either 1-3000 or 1-5000 solution of adrenalin (diluted with either 0.9 NaCl or 5.5% glucose) by continuous or intermittent intravenous infusion. The time interval ranged from 20-60 minutes. The animals were table trained and no anesthetic was used since the slow injection did not cause pain or discomfort. Occasionally a dog would retch or vomit if the adrenalin was given too fast. Arterial pressures were recorded by the needle puncture method 2 during injection and frequently thereafter. The essential data obtained from study of a representative case are given in Table I. The arterial pressure which is high during adrenalin administration may abruptly decline to a low level shortly after cessation of injection, or the fall may be slow but steady. The animals do not show any signs of revival from shock, unless treated. They are unable to spontaneously raise the lowered blood pressure. Eight intact dogs which received approximately equivalent quantities of adrenalin per kg. body weight, given at the rate of 0.5 cc. perminute, died within 10 hours.

Direct Effect of Adrenal Cortical Hormone upon Blood Pressure in Shock Induced by Intestinal Manipulation

The writers 1 have repeatedly called attention to the slow but steady decline in blood pressure which occurs in adrenalectomized dogs after withdrawal of cortical hormone, and have pointed out that following administration of hormone to animals prostrate from adrenal insufficiency the rise in arterial pressure from shock levels to normal is one of the first and most dramatic changes observed during recovery. The fall in pressure is not a terminal event but is one of the earliest changes from normal exhibited by the animal not receiving hormone. During the past year we have performed 4 different types of experiments on adrenalectomized dogs, the results of which show that the cortical hormone exerts a direct effect upon blood pressure which is distinct and separable from the action of this hormone upon blood volume, and fluid and electrolyte distribution. Table I gives the essential data obtained from a representative case in one type of experiment in which intestinal stripping was used to induce shock. Dogs lacking adrenals do not spontaneously raise their lowered blood pressure or recover from this treatment. 2 Seven active, vigorous, adrenalectomized dogs kept for one year in the laboratory on maintenance doses of cortical hormone, were used. The hormone was withheld 18 hours previous to use in the experiments. The animals were in normal health, at peak weight, and revealed no deviations from normal in their blood and urine chemistry, water balance and arterial pressure. They were etherized and a portion of the small intestine vigorously stripped through the fingers for 20-30 minutes. The dogs recovered rapidly from the anesthetic and their activity and vigor appeared undiminished. However, within the ensuing 6-12 hours the arterial pressure declined to shock levels—40-50 mm. Hg. When the dogs were at the point of collapse they were injected intravenously with 3 cc. per kg. body weight of hormone. The arterial pressure slowly but steadily rose and attained the normal level within 36-48 hours. All shock symptoms disappeared and activity and vigor returned. Arterial pressure increases of as much as 5-10 mm. Hg. per hour were not infrequently observed during the first hours following hormone injections. Study of the serum Na, Cl and K showed negligible changes in concentration of these electrolytes. In general the Na and Cl tended to increase slightly and the K to fall. About one-half of the dogs did not show hemoconcentration or loss of extracellular fluids, when in profound shock. Three animals exhibited moderate concentration of the blood in the terminal stages, but in no case was disturbance of fluid or electrolyte balance adequate to account for the vascular collapse. Hypertonic saline (20 cc. of a 20% solution intravenously) also restored the arterial pressure of these animals to normal but the effect was temporary compared to the lasting effect of hormone. We do not know the locus of action of cortical hormone upon blood pressure. However, it may not necessarily be through the mediation of the nerve endings but may be directly upon the musculature of the vascular system. This point is now under investigation. Overdosage effects, either in intact or adrenalectomized dogs, have not been observed despite use of massive doses of hormone. Hoskins and Fierman 3 have described a prolonged pressor effect following oral administration of glycerine extracts of adrenal cortex to human patients. Recent work on experimental hypertension indicates that the cortical hormone is concerned with blood pressure. 4 , 5 The observation that cortical hormone has a direct effect upon blood pressure of adrenalectomized dogs which is separable and distinct from its functional control of the internal fluid and electrolyte balance of the body, in no way invalidates the earlier conclusions based upon the hormones “salt-water” action, as offering a rational explanation of many of the phenomena occurring in adrenal insufficiency. The 2 effects of the hormone when considered together, adequately explain the circulatory collapse of adrenal insufficiency.

Influence of Prolonged Electrolyte Deprivation and Final Restoration on Fluid Intake, Balance and Distribution

Summary Dogs partially depleted of extracellular electrolytes by intraperitoneal glucose injections and then maintained on a salt-free diet showed absence of fluid intake and a negative water balance while the intracellular volumes were above normal. When these volumes had been reduced to stable minimal levels, water was taken by mouth and the negative water balance corrected. Although the intakes now rose to polydipsic levels, a positive balance was not established despite the fact that the extracellular volumes were still reduced. Intracellular volumes were not restored to the preëxperi-mental level. When NaCl was given, extracellular electrolytes and volumes were restored toward normal. The initial response was an increased intake which, however, was not sustained. The intracellular compartment, originally decreased, showed a delayed rehydration to normal levels. Hence the voluntary water intake showed more positive correlation with changes in intracellular volume than with extracellular volume change. Fluid balance was affected both by intracellular hydration and electrolyte levels in the extracellular fluid.

A Modified Method for the Preparation of Renin

Partially purified renin has been prepared in several laboratories from NaCl or cold acetone extracts of the kidney cortex. 1-4 Recently modifications in our original extraction procedure 2 have been introduced which eliminate many of the more cumbersome manipulations involved, with considerable saving of time, without sacrificing the relative high potency of the final product. Extraction Procedure. Demedullated kidneys are ground, frozen, and, before thawing, reground into 2% NaCl solution (10 liters to 3 kg tissue). It is possible to use fresh, unfrozen kidneys, but the extraction appears to be less complete. After the salt extract has been stored for 24 hours under toluene, the meat sludge is removed by straining and centrifuging (Sharpies). The pH is then lowered to 4.5. After an interval of 12 to 24 hours to insure complete precipitation, the heavy precipitate is removed by centrifuging (Sharpies) and filtering through Hyflo Super-Cel.† For easier handling in subsequent procedures, the filtrate, adjusted to pH 6.8, is concentrated in vacuo (maximum temperature 45°C) to a volume of 1 liter. The concentrate is filtered, 100 g NaCl are added and the pH is lowered to 2.0. The heavy precipitate is removed on a filter cake of Hyflo which is then suspended in 2 liters of water. After the pH is raised to neutrality and the suspension thoroughly mixed by a motor stirrer for about 30 minutes, Hyflo and any insoluble precipitate are filtered off and discarded. The filtrate is saturated with solid NaCl and the pH again lowered to 2.0. The precipitate is removed on a filter cake and redissolved in 500 cc N/10 acetate buffer at pH 5. As before, insoluble residue is discarded.

Effect of Extract of Anterior Pituitary upon the Life-Span of Castrate-Adrenalectomized Cats

The writers have reported that a commercial extract of the anterior pituitary prolongs the life-span of bilaterally adrenalectomized cats, but is without effect upon dogs, at any rate in the dosage employed. 1 Two of the 12 animals studied were castrate males. One lived 25 days and succumbed to feline distemper; the other survived 47 days. It was deemed worth while to study the effect of A.P. extract upon the life-span of a larger group of castrate-adrenalectomized cats. Strong, vigorous cats were used. They were given a vermifuge, and a few days later the gonads and right adrenal were removed under nembutal anesthesia. They were then kept in the laboratory for 2 weeks to insure adjustment to laboratory conditions. The animal room was thermostatically regulated. The left adrenal was extirpated under ether and for 2 days following operation the cats received cortical hormone. If the animals were eating full rations at this time cortical hormone was withdrawn and A.P. extract substituted. The experiment began the day cortical hormone was discontinued. The A.P. extract used was prepared by a modification of the method of Van Dyke and Wallen-Lawrence2 and is an alkaline aqueous extract of cattle pituitary made by Squibb & Sons. It contains appreciable amounts of the various pituitary factors. We used freshly prepared non-preserved material since the cats appeared to he sensitive to the merthiolate present in the commercial preparation. The diet consisted of 175 g of canned salmon plus 50 cc of milk daily. This was changed to fresh raw fish, liver and kidney whenever the appetite became capricious. The essential data regarding the effect of A.P. extract upon the life-span are shown in Table I.

Some Factors Involved in the Assay of Renin

Summary The magnitude of the blood pressure rises given by large doses of renin must be corrected for differences in starting pressure levels, while those given by smaller doses need not be. An assay based on repeated tests on 2 or 3 dogs is as reliable as one based on a larger series of animals. Nembutal anesthesia may affect, in some dogs, the magnitude of the rise after large renin doses, but usually has little effect on the rise after small doses. For most routine testing, the anesthetized dog is the preferable test animal.