bluuebunny/crossref_metadata_2025 huggingface dataset:
Gastric secretion and parathyroid function in rats
Authors: Blanshard Gerald , Arabehety Julian T. , Gray Seymour J.
Published: December 2017

The gastric secretory activity was investigated in rats subjected to various states of parathyroid dysfunction. Acute and chronic hypoparathyroidism was induced by parathyroidectomy, and acute and chronic hyperparathyroidism by injections of parathyroid hormone. Chronic hypervitaminosis D was produced by injections of activated Ergosterol. The resulting changes in serum calcium and phosphorus levels were observed. At the end of each experimental period pyloric ligation was performed 4 hours prior to killing, the stomach mucosa examined macroscopically and the gastric juice analyzed. Mucosal congestion and ulceration were observed in rats with chronic hypoparathyroidism, chronic hyperparathyroidism and chronic hypervitaminosis D, but not in normal animals or in those with acute hypo- or hyperparathyroidism. Analysis of the gastric juice revealed no statistically significant differences from the normal in respect to volume, pH, hydrochloric acid, sodium, potassium, calcium, chloride or pepsin content. The development of gastric mucosal congestion and ulceration in various states of parathyroid dysfunction suggests that the apparent ulcerogenic effects are mediated through influences other than the gastric acid, pepsin and electrolyte secretion.
Effect of tetraiodothyroformic acid on oxygen consumption of the cholesterol-thiouracil-fed rat
Authors: Best Maurice M. , Duncan Charles H.
Published: December 2017

The formic acid analogue of thyroxine, tetraiodothyroformic acid, was found to have 0.086% the goiter inhibiting activity of l-thyroxine in the thiouracil-cholesterol-fed rat. With regard to oxygen consumption its activity was 0.084% that of l-thyroxine. In amounts having equal effect on thyroid weight and oxygen consumption, tetraiodothyroformic acid resulted in significantly lower mean liver cholesterol.
Micropuncture study of the mammalian urinary concentrating mechanism: evidence for the countercurrent hypothesis
Authors: Gottschalk Carl W. , Mylle Margaret
Published: December 2017

The osmolality was determined of fluid collected by micropuncture from proximal and distal convolutions, loops of Henle, collecting ducts and vasa recta of kidneys of various rodents with and without osmotic diuresis. Proximal tubular fluid was isosmotic; in the presence of antidiuretic hormone, early distal fluid was hypo-osmotic due to the prior reabsorption of sodium chloride, and late distal fluid again isosmotic. The hyperosmotic concentration of the urine is established in the collecting ducts, apparently as a consequence, in part at least, of the hyperosmotic reabsorption of sodium chloride in the loops of Henle. Fluid from the bends of loops of Henle, and from collecting ducts and vasa recta at the same level were equally hyperosmotic, consistent with the hypothesis that the mammalian nephron functions as a countercurrent multiplier system. The vasa recta are believed to play an important role in the concentration of the urine by functioning as countercurrent diffusion exchangers.
Effect of procaine on electrical properties of squid axon membrane
Authors: Taylor Robert E.
Published: December 2017

Procaine (0.025–0.1%; pH 7.9) caused a reduction in the amount and rate of development of the early transient (sodium) and late steady state (potassium) currents which occur during a depolarizing voltage step applied to the excised, voltage clamped squid axon. Consistent results were obtained by holding the membrane potential at a hyperpolarized value prior to the applied step. No effect was seen on the resting potential, on the sodium equilibrium potential, or on the proportion of the sodium carrying system which was ‘inactive’ at any membrane potential. The blocking action of procaine is a result of the inhibition by the drug of the sodium carrying system. The effect of procaine on the potassium conductance is such as to oppose the blocking action.
Comparison of external loss of sodium with loss from sucrose space in adrenalectomized rats
Authors: Rolf Doris , Armstrong C. M. , Steiger B. W. , Audia M. , White H. L.
Published: December 2017

Using 1-hour sucrose space in rats as a measure of extracellular fluid (ECF) volume, net loss of Na from ECF is found to agree closely with external loss (balance data) 6 days after adrenalectomy. No significant exchange of Na between ECF and intact cells is evident following adrenalectomy. Fair correspondence of net loss of Na from ECF with external loss was also seen in normal rats mildly depleted of Na by 6 days on an essentially Na-free diet. Sucrose space (ml/kg final weight) is 225 ± 12 in normal rats, 197 ± 13 in adrenalectomized, and 209 ± 9 in normal rats after 6 days on an essentially Na-free diet. Evidence is presented that sucrose space measure a reproducible ECF compartment in normal, adrenalectomized and salt-depleted rats.
Local effect of serotonin on renal vascular resistance and urine flow rate
Authors: Emanuel D. A. , Scott J. , Collins R. , Haddy F. J.
Published: December 2017

The effect of serotonin upon renal vascular resistance and urine flow rate when infused directly into the renal artery was studied in 37 laparotomized anesthetized dogs. Concentrations of 10 and 100 µg/min. were utilized in kidneys that were innervated, denervated and denervated plus infused with a sympatholytic and adrenolytic agent. In one series, blood flow rate was maintained constant with a pump interposed in the renal artery. Pressures were measured in the renal artery and vein. Changes in renal vascular resistance in nerve intact, denervated and denervated phentolaminized kidneys were +0.14 ± 0.14, +0.16 ± 0.11 and +0.09 ± 0.07 mm Hg/ml/min. Urine flow rate did not change. In a second series, urine flow rate and aortic pressure were measured without the blood pump. Urine flow rate changes for intact, denervated and denervated phentolaminized kidneys were –0.30 ± 0.43, –0.06 ± 0.44 and 0.00 ± 0.37 ml/min. Aortic pressure remained constant. These data indicate that the local effect of serotonin in the amount used is to actively increase the geometric component of renal vascular resistance through some mechanism unrelated to extrinsic nerves and circulating or locally released catecholamines. Under the conditions of the study, regular changes in urine flow rate were not observed.
5-Hydroxytryptophan decarboxylase activity in rat mast cells
Authors: Lagunoff David , Benditt Earl P.
Published: December 2017

Mast cells of rats contain, in addition to histamine and heparin, serotonin. This study was undertaken to determine the ability of mast cells to synthesize serotonin. Preliminary experiments demonstrated a positive correlation between mast cell concentration in different rat tissues and 5-hydroxytryptophan decarboxylase activity. An attempt to demonstrate this activity directly in peritoneal mast cells separated from other cells by centrifugation through a high density sucrose solution was unsuccessful. A new method of separating mast cells was developed employing concentrated bovine albumin solution. The mast cells could be centrifuged through this solution; most other cells remained at the interface. Mast cells separated in purities of 40–80% contained decarboxylase activity at a similar level to that of centrifuged unpurified mast cells. Characteristics of the mast cell decarboxylase system were investigated using peritoneal washings which contained 5% mast cells. The decarboxylase was inhibited by substrate concentrations greater than 1 mg/ml. The activity of the decarboxylase system was enhanced by the addition of pyridoxal-5-phosphate. A pH optimum of 7.5 was found for the decarboxylase activity in the cells.
Assimilation and dissimilation of fatty acids by the rat liver
Authors: Stein Y. , Shapiro B.
Published: December 2017

Up to 60% of i.v. injected doses of 1-C14 palmitic acid was found in the liver 15 minutes after injection, two thirds in the form of triglycerides and the rest as phospholipids. Almost no radioactive UFA could be demonstrated in the liver or in blood plasma. Thereafter, the activity in the triglyceride fraction fell rapidly, only 50% remaining after 1 hour. At the same time the phospholipid activity increased. With 1-C14 linoleic acid a similar pattern was found, except that the percentage retained in the liver was lower and maximum retention was found after 5 minutes. Fifteen minutes after injection of 1-C14 palmitate most of the radioactive glycerides in the liver were found in the microsomes and mitochondria, with very little in the floating fat. Equilibration between these cytoplasmatic particles occurred only after 2 hours. Perfusion of the liver in situ with blood or blood substitutes, after various periods following 1-C14 palmitic acid injection, caused a release of about 5–20% of the liver triglycerides and 0.5–2% of the liver phospholipids per hour.
Role of the adrenal in hastening blood coagulation after exposure to stress
Authors: Friedman Meyer , Uhley Herman N.
Published: December 2017

The possible role of the adrenal gland in the hastening of blood coagulation in rats exposed to a particular form of stress was investigated. It was observed that there was a marked fall in adrenal cholesterol content during the period of stress. However, the hastening in blood coagulation after exposure to the stress was not altered by removal of the adrenal glands. It, therefore, was concluded that the coagulation phenomenon observed was independent o adrenal activity.
Dual contractile response of the aorta strip
Authors: Brodie Donald C. , Bohr David F. , Smit Jeanette
Published: December 2017

Isotonic contractions of rabbit aorta strips recorded in response to chemical stimuli strongly suggest that the shortening process has a dual character, consisting of a fast (F-) and a slow (S-) component. In the current study evidence for a dual contractile mechanism was sought by attempting to separate one component from the other. The S-component is more altered than the F-component by shifts in electrolyte composition. The S-component is less activated than the F-component by low concentrations of epinephrine or norepinephrine. The F-component is less activated than the S-component by low concentrations of phenylephrine or isopropylarterenol. The differential effect of reduced temperature is the same as that produced by a decrease in concentration of the constrictor. Dibenamine blockade permits a differentiation of the two components since it seems to alter the ratio of available receptors which activate the two components. When norepinephrine was used in high concentrations after Dibenamine blockade it caused a separation of the F- and S-components by imposing a period of relaxation between the two.
Alloxan diabetes and dextran "anaphylactoid" inflammation
Authors: Adamkiewicz V. W. , Adamkiewicz Lidia M.
Published: December 2017

The dextran "anaphylactoid" inflammation in the rat does not occur during alloxan diabetes. It is restored by insulin administration. The inhibition of this inflammation during alloxan diabetes is mainly due to the lack of insulin.
Blood volume and red cell concentration in the normal chick embryo
Authors: Barnes Arthur E. , Jensen Wallace N.
Published: December 2017

A method for the determination of red cell mass, which employs the use of radioisotopically-labeled erythrocytes, in the embryonated hen egg is described and results of total blood volume, plasma volume, red cell mass and red cell concentration determinations during the period from 9 to 18 days of incubation presented. Considerations of the values obtained in terms of absolute quantities and relative to embryonic mass are discussed. It is suggested that expansion of the red cell mass and somatic growth are portions of a common process and may be subject to a complex of similar regulatory factors in the normal chick embryo.
Osmotic effects and diffusion of nonelectrolytes in muscle
Authors: Bozler Emil
Published: December 2017

Osmotic effects and distribution of some nonelectrolytes were studied in the frog's sartorius and stomach muscle. Diffusion of urea and thiourea, determined by chemical methods, was more than 90% complete in 1 hour. Nevertheless Ringer's solution to which these substances were added caused reversible shrinkage which, in the sartorius, persisted for many hours. To explain this result and previous observations on stomach muscle it is suggested that a large part of the fiber water is contained in narrow spaces, hindering diffusion of molecules as small as those of urea. That semipermeability is a property of muscle fibers in bulk is supported by the observation that sugars have a long lasting osmotic action on thin transverse slices of the sartorius. This hypothesis also explains that, at the same osmotic pressure, the osmotic effects of nonelectrolytes vary widely, increasing in the order urea < erythritol < ribose < sucrose.
Effect of potassium on small and large blood vessels of the dog forelimb
Authors: Emanuel Dean A. , Scott Jerry B. , Haddy Francis J.
Published: December 2017

Potassium salts were infused into the brachial artery while holding the rate of blood flow constant and measuring pressures at four sites along the length of the bed. Small vessel resistance progressively decreased as a function of infusion rate. Arterial resistance did not change and then increased as a function of infusion rate. The net effect was a decrease and then an increase in total resistance. The decrease was associated with lessened responses to norepinephrine and acetylbetamethylcholine, serum potassium concentrations in the leg up to about 8 mEq/l. and no change of serum concentration in the body as a whole. The increase in resistance was associated with serum concentrations in the leg in excess of 8 mEq/l. and slight elevation of concentrations in the body as a whole. The decrease of small vessel resistance was lessened but still present following denervation of the leg and adrenergic blockade. Arterial resistance did not increase following adrenergic blockade. Those findings indicate that potassium excess dilates arterioles in the dog foreleg by a direct action as well as by decreasing the sensitivity of the arteriole to natural pressor substances. The large arterial constriction may be related to an adrenal discharge.
Sympathetic cardiac stimulating fibers in the vagi
Authors: Benítez D. , Holmgren B. , Middleton S.
Published: December 2017

The cardiac effects obtained by the stimulation of the vagus nerve were studied in the isolated heart preparation of cats, perfused with Tyrode's solution according to Langendorff's technique. High cervical stimulation of the vagus produced slight or no positive inotropic and chronotropic effects in the atropinized heart. Excitation of the thoracic portion produced intense cardiac stimulation. The cardiac stimulating effect is not influenced by supra- or infranodose vagotomy. Complete cervical and upper thoracic sympathectomy abolished vagal cardiac stimulation. It is concluded that sympathetic fibers that join the vagal trunk at the lower cervical and, perhaps, upper thoracic level, are responsible for the positive chrono and inotropic effects obtained when stimulating the intact or degenerated vagus nerve.
Physiological disposition of d- and l-thyroxine in the rat
Authors: Tapley D. F. , Davidoff F. F. , Hatfield W. B. , Ross J. E.
Published: December 2017

A comparison was made of the distribution and excretion of the optical isomers of thyroxine in the rat. d-Thyroxine disappeared more rapidly from the blood and was concentrated to a greater extent in the liver and kidney than was l-thyroxine. The concentration of d-thyroxine in such peripheral tissues as muscle, brain and skin was much less than the concentration of l-thyroxine. This difference in distribution to the peripheral tissues was of such magnitude as to suggest a possible basis for the different activities of the two isomers observed in vivo. The half-time of d-thyroxine in the body (14 hr.) was significantly shorter than that of l-thyroxine (42 hr.).
Corticosterone rhythm of mouse adrenal in relation to serum corticosterone and sampling
Authors: Halberg Franz , Albrecht Paul G. , Bittner John J.
Published: December 2017

Under conditions standardized for light-synchronized periodicity analysis the corticosterone content of mouse adrenals undergoes significant 24-hour periodic changes. In mature males of the B1 stock, glandular hormone content fluctuates by approximately 50% around its day-mean, accounting amplitude-wise for about one-half of the periodic change in blood hormone. Peak corticosterone content in the adrenal occurs at ≈16:00, if mice are kept on a regimen providing for light from 06:00 to 18:00, alternating with 12 hours of darkness. As to timing, the daily corticosterone peak in the gland corresponds roughly to that in serum, when sampling is done at 4-hour intervals in the absence of stimulation other than daily routine. The correlation between physiologic 24-hour changes of corticosterone in adrenal and serum is positive and statistically significant. This correlation may be altered by the conditions of sampling, e.g. by the repeated exposure of mice to man.
Renal excretory transport of organic acids: inhibition by oxypurines
Authors: Despopoulos Agamemnon
Published: December 2017

Uric acid inhibited the active accumulation of p-aminohippurate (PAH) by surviving slices of rabbit kidney cortex without affecting oxygen utilization or oxidative phosphorylation. The inhibitory potency of uric acid was compared with that of several desoxyurates and N-methylated urates. In general, the desoxyurates were less potent and the N-methylated urates more potent inhibitors than uric acid. The data suggest that the inhibitory reaction requires the presence of all three oxygen atoms of the urate molecule. These appear to function as carbonyl groups rather than as enolic hydroxyl groups in a predominantly nonionic reaction.
Oxygen consumption and blood flow in the hypothermic, perfused kidney
Authors: Levy Matthew N.
Published: December 2017

Temperature was diminished in a stepwise fashion in the isolated kidney of the dog perfused from a peripheral artery of the original, normothermic animal. Decreased temperature resulted in an appreciable reduction of renal blood flow at constant arterial blood pressure. Increased blood viscosity and vasoconstriction were both responsible for this reduction of flow. Hypothermia also resulted in a reduction in arteriovenous oxygen difference which was roughly proportional to the centigrade temperature. Furthermore, hypothermia exerted a marked but reversible depression of the rate of oxidative metabolism. This effect was relatively more severe than the changes for the body as a whole at equivalent temperatures reported by other investigators.
Pulmonary vascular effects of serotonin (5-OH-tryptamine) in dogs: its role in causing pulmonary edema
Authors: Kabins S. A. , Molina C. , Katz L. N.
Published: December 2017

Rapid injection of serotonin (0.5–6.5 mg) was made into the pulmonary artery in 22 experiments in 12 open-chest anesthetized dogs. Serotonin caused pulmonary arteriolar and venous constriction in the majority of experiments, shown by an increase in the pressure gradients between the pulmonary artery and pulmonary artery wedge pressures, and between the latter and the left atrial pressure, respectively. Three groups of responses were obtained as far as the production of pulmonary edema is concerned. The first group (3 dogs) showed no pulmonary edema. The second ( group II—6 dogs) showed moderate to severe bilateral pulmonary edema without evidence of left heart failure. The third (3 dogs) also showed severe bilateral pulmonary edema but in the presence of left heart failure. In group II, the evidence suggests that an increase in capillary permeability is responsible, at least in part, for the pulmonary edema found. The similarity of results in group II to those obtained in the formation of bilateral pulmonary edema following unilateral starch embolization, suggests that serotonin could be the initiating factor in the neurohumoral mechanisms involved—or one of them.
Effects of polycythemia and anemia on cardiac output and other circulatory factors
Authors: Richardson Travis Q. , Guyton Arthur C.
Published: December 2017

Normovolemic anemia and polycythemia were studied in 14 dogs. Cardiac outputs increased with anemia and fell with rises in hematocrit. Although many factors—such as chemical changes—may play an important role in these variations in cardiac output, there was an indication that viscosity alone may have a major effect. There was no significant association between changes in cardiac output and the various pressures—mean arterial, mean right atrial, mean pulmonary and mean circulatory. Although the pressures did not change significantly, there was a significant decrease in total peripheral resistance in anemia and a marked rise in polycythemia. It was also found that the maximum number of red cells present for oxygen transport to the tissues was near the mean normal hematocrit of 40.
Electrical activity of striated muscle in experimental vitamin E deficiency
Authors: Fudema John J. , Oester Yvo T. , Fizzell James A. , Gatz Arthur J.
Published: December 2017

Electromyographic examinations were made on skeletal muscles of rabbits in which nutritional muscular dystrophy had been produced by means of a vitamin E-deficient diet. Control animals on the same diet but including vitamin E (alpha-tocopherol) showed no alteration in electromyographic findings during the course of the study. In the vitamin E-deficient rabbits, electromyographic findings were: a) motor unit potentials became complex in character (polyphasic potentials); b) in later stages, motor unit potentials appeared as prolonged complexes of many short-duration, low-amplitude spikes; c) in muscles at rest, spontaneous fibrillation potentials appeared after 15 days; d) positive sharp or ‘V’ waves were observed in the early stage of the E deficiency. Considering the electrical characteristics such as wave form amplitude, and duration, and their other physiological properties, no difference was seen between the fibrillation potentials from skeletal muscles of vitamin E-deficient rabbits and the fibrillation potentials from denervated skeletal muscles of rabbits after nerve section.
Regional differences in capillary permeability
Authors: Mayerson H. S. , Wolfram C. G. , Shirley H. H. , Wasserman K.
Published: December 2017

Cervical, intestinal and hepatic lymphatics are cannulated in Nembutalized dogs and I131-labeled serum albumin and dextran fractions of average molecular weights from 10,600 to 412,000 are simultaneously infused. The concentrations of the test molecules are periodically determined in plasma and lymph. ‘Steady state’ concentration lymph/plasma ratios for each test molecule are related to those for albumin and a coefficient obtained which relates the permeability of a capillary bed to a given molecular weight of dextran to its permeability to albumin. This makes it possible to accurately compare permeabilities to different size dextrans from dog to dog. The data indicate the presence of two discrete sets of ‘pores:’ 1) a set of ‘small pores’ allowing passage of molecules not greater than 250,000 M; 2) ‘large pores’ permitting passage of molecules of at least 412,000 M. An alternate suggestion is made that molecules of greater than 250,000 M are transferred by the process of ‘cytopemphis’ rather than passage through pores.
Increased circulating plasma volume following phenoxybenzamine (Dibenzyline)
Authors: Williams Francis L. , Rodbard Simon
Published: December 2017

Dibenzyline (phenoxybenzamine hydrochloride; N-phenoxyisopropyl-N-benzyl-ß-chloroethylamine hydrochloride) produced a marked increase in the circulating plasma volume (T-1824) in the normothermic chick. It prevented most of the reduction in plasma volume which usually occurs during induced hypothermia. Calculated red cell mass was unaffected. Pentolinium and tetraethylammonium had no effects on either the plasma or cell volumes in normal or hypothermic chicks. Discriminatory sequestration of plasma and blood cells in different vascular beds is suggested, perhaps via neurogenic mechanisms.
Hydrocortisone-induced changes in hepatic glucose-6-phosphatase and fructose diphosphatase activities
Authors: Kvam Donald C. , Parks R. E.
Published: December 2017

The marked increases in hepatic glucose-6-phosphatase and fructose diphosphatase activities observed after hydrocortisone administration in adrenalectomized rats is inhibited by treating the animals with the methionine antagonist, ethionine. This inhibition is, in turn, reversed by the administration of methionine. This is further evidence that these increases represent adaptive enzyme formation involving the synthesis of new protein. In the presence of ethionine both blood sugar and hepatic glycogen levels rise after hydrocortisone injection but to values distinctly below those found when adaptive enzyme formation can occur. Ethionine treatment does not affect the rate at which blood sugar and hepatic glycogen concentrations increase for the first 6–12 hours after glucocorticoid injection. The increases in hepatic glucose 6-phosphatase and fructose diphosphatase activities induced by a diet high in sucrose do not occur in adrenalectomized rats.
In vitro synthesis of lipids from C-14 acetate by adipose tissue from four types of obese mice
Authors: Hollifield Guy , Parson William , Ayers Carlos R.
Published: December 2017

Adipose tissue slices from four types of fasted obese mice (mice with the hereditary obesity diabetes syndrome, yellow mice, gold thioglucose obese mice and mice made obese by the subcutaneous implantation of pellets of 11-dehydrocorticosterone) and appropriate controls were incubated with C-14-labeled acetate. Adipose tissue slices from mice with the hereditary obesity diabetes syndrome and mice made obese with 11-dehydrocorticosterone incorporated considerably more C-14 into lipids per milligram of adipose tissue nitrogen than did control animals. Slices from yellow mice incorporated less C-14 into lipids than Balb/c controls, but the difference is not clearly significant. These findings, coupled with the evidence that mice with the hereditary obesity diabetes syndrome and mice treated with 11-dehydrocorticosterone have islet cell hypertrophy of their pancreata, suggests that the obesity in these animals may be related to increased insulin production with a resultant increase in lipid synthesis by adipose tissue.
Glucose and the dextran ‘anaphylactoid’ inflammation
Authors: Adamkiewicz V. W. , Adamkiewicz Lidia M.
Published: December 2017

Male Sprague-Dawley rats, 120–150 gm in body weight, injected simultaneously with the glucan dextran (1 ml 6% w/v, i.p.) and with an overdose of glucose (3 x 5 ml, 25% w/v, s.c.) which cannot be markedly reduced by excretion in about 24 hours, do not undergo dextran ‘anaphylactoid’ inflammation. If the amount of glucose is smaller (2 x 5 ml, 25% w/v, s.c.) and can be reduced by excretion within about 10 hours, the inflammation occurs, but is greatly delayed in time and diminished in intensity. The specific inhibitory action glucose exerts on the biological activity of the glucan dextran is discussed.
Renal function in hypertensive cardiovascular disease of rat
Authors: White Fred N. , Sambhi M. P. , Grollman Arthur
Published: December 2017

Rats were rendered hypertensive by subjecting them at the time of weaning for a period of several weeks to a choline-free or potassium-free diet. Urea clearance, renal blood flow and tubular mass of the chronically hypertensive animals remained normal. Only the glomerular filtrate rate was significantly reduced in the hypertensive animals reflecting the changes in the glomerular membrane induced by the experimental procedure. However, there was no correlation between the severity of the blood pressure and the observed morphological or functional disturbance in the glomerulus. It is concluded that the experimentally induced hypertension, like its human counterpart (essential hypertension) is not a consequence of renal ischemia nor is it dependent upon the concomitant presence of renal excretory insufficiency.
Renal transport sites for K, H and NH3. Effect of impermeant anions on their transport
Authors: Sullivan Lawrence P. , Wilde Walter S. , Malvin Richard L.
Published: December 2017

The stop flow technique was used to locate the sites of the renal transport mechanisms for potassium, hydrogen and ammonium. Data were obtained which indicate that these cations are secreted in a very distal area of the nephron, presumably in the collecting ducts. Potassium reabsorption also occurs in a distal area immediately proximal to the secretory site. Infusions of thiosulfate, ferrocyanide and phosphate alter the stop flow concentration patterns so that secretion of the cations appears to take place throughout the distal tubule and to be coextensive with distal sodium reabsorption. No clear indication of potassium reabsorption is evident under these circumstances. It is suggested that these anions, because of the impermeability of the distal tubule to them and because of their negative charge, attract hydrogen and potassium into the tubular lumen as sodium is reabsorbed. In effect, an abnormal exchange mechanism is created at a site proximal to that where active secretion of hydrogen and potassium occurs.
Accumulation of Ca45 by slices of the small intestine
Authors: Schachter David , Dowdle Eugene B. , Schenker Harris
Published: December 2017

Respiring slices of the proximal small intestine of the rat accumulate Ca45 in vitro, and after 1 hour of incubation at 37°C the Ca45 concentration ratio tissue/medium is approximately 5. When oxidative metabolism is prevented by incubation under N2, or when the generation of phosphate-bond energy is inhibited with 2,4-dinitrophenol, the corresponding Ca45 ratio tissue/medium is approximately 2. The oxygen-dependent accumulation of Ca45 is limited in capacity, relatively specific for Ca++ in contrast to Sr++ or Ba++, inhibited by K+, and dependent on the dietary vitamin D. It is greater with slices from young, growing rats than with those from older rats. The results indicate that the accumulation of Ca45 by slices results mainly from the active transfer of calcium previously observed with everted gut-sacs.
Changes in twitch tension induced by quick stretch and stress relaxation
Authors: Walker Sheppard M. , Thomas Antoinette G.
Published: December 2017

The triceps surae of male rats was prepared in situ for isometric recording and for stimulation through the cut sciatic nerve. A study was made on changes of twitch tension induced by quick stretch, stress relaxation and slow stretch. Quick stretch applied immediately before the twitch response produces changes of twitch tension similar to those obtained by slow stretch. Stress relaxation after quick stretch is accompanied by twitch tension greater than that obtainable after slow stretch at all lengths of the muscle observed. The amount of increase of twitch tension induced by stress relaxation is large below the optimum length and small beyond the optimum length of the muscle. When stress relaxation is virtually complete, this increase of twitch tension disappears, the magnitude of the twitch being thereafter equal to that obtainable by slow stretch. It is suggested that the increase is due to a dynamic state of the length-resting tension relationship during stress relaxation when length is increasing and tension is decreasing. Disappearance of the increase of twitch tension when length-resting tension equilibrium is established after stress relaxation supports this suggestion.
Mechanisms leading to lung edema in pulmonary embolization
Authors: Kabins S. A. , Fridman J. , Neustadt J. , Espinosa G. , Katz L. N.
Published: December 2017

A localized pulmonary infarction was produced by injecting a starch suspension into the pulmonary artery wedge position of one lung lobe in pentobarbitalized dogs, and the effect of three so-called antiserotonins on the ensuing pulmonary edema was determined. Edema was inhibited in the nonembolized lung lobes in 88% of the B.A.S. (1-benzyl-2-methyl-5-methoxytryptamine HCl), 45% of the DHE (dihydroergotamine), and 12% of the BOL (2-brom- d-lysergic acid diethylamide) dogs. Reasons are given for assuming that the actions of B.A.S. and DHE are due to their antiadrenergic rather than to any antiserotonin properties which they may have. Serotonin, therefore, at most has a slight role in the pulmonary edema formation caused by starch emboli. It is postulated that the emboli by producing an infarct and setting up a reflex mediated through the sympathetic nervous system, cause the release in turn of catecholamines and of histamine, the latter being immediately responsible for the capillary permeability change leading to pulmonary edema.
In vitro leucine incorporation into protein of normal and x-irradiated rabbit bone marrow cells
Authors: Uyeki Edwin M. , Key Harvey , Salerno Paul R.
Published: December 2017

When compared with nonirradiated controls, the isolated bone marrow cells of x-irradiated rabbits showed a decrease ( ca. 40%) in the in vitro uptake of labeled leucine into proteins 1 and 2 days after exposure to 400 r and 800 r. A similar magnitude of inhibition of leucine incorporation was observed in hemibody x-irradiated rabbits in which the marrow cells from the irradiated femur were compared with that from the nonirradiated side. The decreased uptake of leucine into protein after radiation may be due to an interruption in the supply of young forms during the postirradiation period, and hence, the decreased uptake of amino acids into proteins may be characteristic of the mature cells of the surviving cellular elements.
Latent period in the induction of reticuloendothelial blockade
Authors: Parker Howard G. , Finney Caroline R.
Published: December 2017

Double intravenous injections of colloidal carbon in the mouse, with variation of the time between doses and with blood disappearance curves taken after the second dose, revealed a delay of over 3 hours in onset of reticuloendothelial blockade due to the first carbon dose. This was so despite the virtual disappearance of the latter from the blood within two hours. The degree, duration and approximate time of onset of blockade did not change when the blocking dose was varied twofold. Carbon phagocytic rates returned to normal between 3 and 6 days after the first dose, without indicating any secondary period of phagocytic stimulation. Evidence is presented that carbon phagocytosis in the mouse is a complicated reaction sequence whose over-all rate is neither independent of particle concentration nor directly proportional to it.
Proliferation of the reticuloendothelial system in the liver
Authors: Kelly Lola S. , Dobson Ernest L. , Finney Caroline R. , Hirsch J. Dorothy
Published: December 2017

The rate of removal from blood of intravenously injected colloidal carbon was used to measure the functional capacity of liver phagocytes. The carbon disappearance rate constant was initially reduced and gradually returned to normal following injection into mice of saccharated iron oxide or colloidal carbon. This index of phagocytic activity increased above normal after zymosan, estradiol or bacterial endotoxin administration. To determine whether these increases were associated with cell proliferation, liver DNA synthesis was measured. Incorporation of radioactive phosphate into DNA of mouse livers rose markedly after administration of these substances. To characterize the cell type responsible for the large increases in DNA synthesis, radioautographs of liver sections were prepared from mice previously given tritium-labeled thymidine. The label was rarely seen in parenchymal cells, whereas many littoral cells were labeled.
Effects of exogenous serotonin on paleocortical excitability
Authors: Revzin A. M. , Costa E.
Published: December 2017

Exogenous serotonin, in doses to 1 mg/kg i.v., has been found not to affect the excitability of the neurons in the amygdala to hippocampus multineuronal pathway of the limbic system. This is viewed as evidence in support of the hypothesis that injected serotonin does not exert its central effects through a direct synaptic action.
Quantitative measurement of blood flow in various areas of small and large intestine
Authors: Geber William F.
Published: December 2017

A direct method is presented for the continuous quantitative measurement of blood flow in various areas of the small and large intestine. The mean blood flows of the duodenum, jejunum, ileum and descending colon were 1.39, 0.98, 0.83 and 0.73 ml/gm wet tissue/min. The cannulation of the intestinal artery to any intestinal area does not appear to interfere with the blood flow or pressure to the area. With proper precautions, a preparation will last 5 hours before measurable changes in blood flow and pressure occur.
Concentration profiles in and around capillaries
Authors: Blum Jacob J.
Published: December 2017

Capillaries, idealized as uniform cylinders through which blood flows at a constant velocity, supply substrate to the surrounding tissue, where it is consumed according to zero order or first order kinetics. Equations are developed which permit the calculation of the steady state concentration of substrate at any point inside the capillary or the tissue. The effects of finite membrane permeability and of longitudinal diffusion in the tissue are discussed. Computations are presented to show the effects of various biological parameters on the concentration profiles.
Physical basis of the dependence of blood viscosity on tube radius
Authors: Haynes Robert H.
Published: December 2017

Two theories are applied to measurements of the decrease in apparent viscosity of blood in narrow tubes (Fahraeus-Lindqvist effect). First, the effect may be attributed to the presence of unsheared laminae in the fluid (sigma phenomenon), and it was found that the thickness of such laminae must vary between 3.5 µ at 10% hematocrit and 34 µ at 80%. Alternatively, the effect may be caused by a cell-free marginal zone adjacent to the tube wall, which would have to be 6 µ thick at 10% hematocrit and 1.5 µ at 80%. There is a slight suggestion in the data that the effect may be reversed as the flow rate approaches zero (i.e. the apparent viscosity rises in small tubes). Finally, a method is proposed for calculating the effective diameter of a vascular bed, and it was found to be 55 µ for a dog's hind limb.
Effect of salt feeding on thyroid metabolism of I131 in the dog
Authors: Boatman Joseph B. , Rabinovitz Marvin J. , Walsh John M.
Published: December 2017

Six adult male dogs were fed on 5% NaCl added to the same diet on which a group of six dogs were maintained as a control group. At 12 weeks 24-hour I131 uptake, PBI131, serum and urine sodium and potassium were measured. Two weeks later, 5-hour Na24 and I131thyroxine dilution curves were determined from serial blood samples in the anesthetized animals. The salt fed dogs had elevated 24-hour I131 uptake and PBI131, decreased serum sodium and increased serum potassium, and both total urine sodium and potassium were increased with salt feeding at 12 weeks. In the salt-fed dog, both Na24 and I131-thyroxine dilution volumes were increased at 5 hours over the values for the control group, indicating expansion of extravascular volume. It was suggested that alterations of I131 metabolism were influenced by extrarenal factors of expanded fluid volume and tissue concentration of electrolytes in addition to the dominant factor of renal electrolyte regulation with salt loading.
Effects of hypophysectomy on tissue mast cell numbers and heparin levels in the rat
Authors: Marx L. , Armstrong C. W. , Rucker P. , Marx W.
Published: December 2017

The effects of hypophysectomy on tissue mast cell counts and heparin concentrations were studied in male rats 1 1/2–2 months old. It was observed that removal of the pituitary gland caused a significant elevation of the mast cell numbers in liver, lung and kidney, but not in the spleen; thymus showed a trend toward increased values. The heparin contents of the organs examined were not significantly modified by the operation; the kidneys exhibited a trend toward higher values.
Relationship of the middle hypothalamus to amygdalar hyperphagia
Authors: Morgane P. J. , Kosman A. J.
Published: December 2017

Stereotaxic lesions in the lateral hypothalamus of the cat at the level of the tuberal region were found not to alter food intake or body weight from preoperative control levels whereas lesions restricted to the ventromedial nuclei produced hyperphagia and obesity. Cats with combined lateral and ventromedial lesions showed no changes in food intake or body weight. Cats with combined amygdalar, lateral and ventromedial lesions developed hyperphagia and obesity but the rates of weight gain were about three times faster than occurred with amygdalectomy alone. Food intake in this group after operation more than doubled preoperative levels and the gain in weight of the group during the dynamic phase of obesity amounted to 23.6% as compared to 2.3% for normal and sham-operated controls. It is concluded that the lateral hypothalamus does not function as a ‘feeding’ center in the cat but that the ventromedial nucleus is probably a ‘satiety’ center. Furthermore it is probable that inhibitory amygdalar effects on food intake do not operate through the middle hypothalamus since hyperphagia and obesity results following destruction of the entire middle hypothalamus and amygdalae.
Dependency of oxygen consumption of skeletal muscle on number of stimuli during work in the dog
Authors: Fales John T. , Heisey S. Richard , Zierler Kenneth L.
Published: December 2017

The amount of extra oxygen consumed by skeletal muscle following work (isotonic contractions) or isometric contractions was measured in the normally circulated gastrocnemius-plantaris muscle group of the dog. Work was varied by: a) having the muscle perform the same work a repeated number of times; b) varying the load against which the muscle-contracted, c) varying the amount of shortening of the muscle by limiting the duration of stimulation. The effect of frequency of stimulation was assessed by using two frequencies of stimulation in conditions a) and c). Finally, the extra oxygen consumed following isotonic work was compared with the extra oxygen consumed following isometric tension development. It was found that extra oxygen consumption of skeletal muscle following activity was not a direct consequence of the work done nor was it related linearly to the amount of shortening. The extra oxygen consumption appeared to be a response to the number of nervous stimuli delivered to the muscle. At a sufficiently low frequency each stimulus evoked the consumption of a constant quantum of oxygen. At higher frequencies, after a relatively small number of stimuli, oxygen consumption per stimulus decreased with successive stimuli.
Effects of cold stress on mitochondrial oxidative phosphorylation
Authors: Patkin Judith , Masoro E. J.
Published: December 2017

The P:O ratio with succinate as substrate is the same for liver mitochondria from ‘cold-fasted’ rats as it is for mitochondria from control rats. Glucose-hexokinase acceptor studies with either succinate or glutamate as substrate indicate that the oxidative phosphorylating system is about as tightly coupled in the liver mitochondria from cold-fasted rats as it is in those from control rats. These results were surprising since earlier work with liver homogenates indicated that the efficiency of oxidative phosphorylation is markedly reduced in the homogenate from cold-fasted rats. The possible reasons for these differences in results with homogenates on the one hand and mitochondria on the other are discussed. The use of mitochondrial activities as an index of the efficiency of oxidative phosphorylation in vivo is also discussed.
Physiological characteristics of rats and ground squirrels during prolonged lethargic hypothermia
Authors: Popovic V.
Published: December 2017

After intensive cooling, rats can be maintained at constant body temperature during several hours in a cylinder surrounded by cold water. The rats live in lethargic hypothermia at a body temperature of 15°C for 8–10 hours but can recover only if the hypothermia has not lasted more than 5.5 hours, average time of ‘biological survival.’ After 6 or more hours at 15°C adult rats showed irreversible hemoconcentration, hypoglycemia, drop in arterial blood pressure and low pH of the blood, but no change in pulse rate. Artificially cooled ground squirrels survived 110 hours at a body temperature of 10°C, ‘biological survival’ time being only 75 hours. Hemoconcentration, low arterial blood pressure and hypoglycemia have also been found in lethargic ground squirrels during the last part of survival. They cannot be rescued by rewarming. The deeply cooled animal with stabilized temperature is in a physiological state that changes with time and ultimately leads to death. A recovery prognosis during long-term hypothermia has been attempted, and the cause of death has been discussed.
Mitochondrial changes in developing rat brain
Authors: Samson Frederick E. , Balfour William M. , Jacobs Roberta J.
Published: December 2017

The cerebral energy requirement increases during neonatal maturation with a corresponding increase in mitochondrial protein. The question arises: do cerebral mitochondria change in number or in size during this period? Particulates prepared by differential centrifugation from rats of known ages were counted with phase contrast microscopy, also the dry weight and protein determined. The number of mitochondria per gram of brain is (12) (1010) in 1-day rats, (30) (1010) in 21-day rats, (33) (1010) in 50-day rats. The average dry weight in picograms of a mitochondrion is 0.387 in 1-day; 0.308 in 21-day; 0.288 in 50-day. The protein is 0.159 in 1-day; 0.122 in 21-day; and 0.107 in 50-day. Thus it appears there is a threefold increase in the number from 1 to 21 days but the mass per mitochondrion decreases. There is little change in number from 21- to 50-day and the mass continues to decrease. Calculation from the known total dry weight and protein increase per gram of brain shows that 66% of dry weight and 64% of the new protein synthesized is mitochondrial.
Effect of certain thyroxine analogues on liver cholesterol
Authors: Best Maurice M. , Duncan Charles H.
Published: December 2017

l-Thyroxine, l-triiodothyronine, their d-isomers, and their formic, acetic, propionic and butyric acid analogues were given to cholesterol-thiouracil-fed rats and the effect on thyroid weight and serum and liver cholesterol determined. l-Thyroxine, d-thyroxine and tetraiodothyroformic acid were also given to cholesterol-fed rats and the effect on oxygen use and serum and liver cholesterol measured. The substitution of either d-alanine or a carboxyl group for the l-alanine side chain of thyroxine and triiodothyronine resulted in a degree of dissociation of goiter-inhibiting and liver cholesterol effects. Thus, these substituted compounds at doses having equal or less goiter-inhibiting effects resulted in significantly lower liver cholesterol levels than did l-thyroxine or l-triiodothyronine. The effect of d-thyroxine and tetraiodothyroformic acid on liver cholesterol was also disproportionate to their calorigenic activity as compared to l-thyroxine.
Effects of arousal reaction on nystagmus habituation in the cat
Authors: Crampton George H. , Schwam Wallace J.
Published: December 2017

The effects of the arousal reaction on the reduction or habituation of nystagmus in the unanesthetized cat repeatedly rotated in darkness were determined. A reduction in nystagmus was associated with a reduction of alertness as indicated by the electroencephalogram, but alerting an animal by sounds occasioned only a temporary and partial recovery of nystagmus. Further, a continuous arousal sustained by cutaneous electric shock stimuli did not prevent habituation. It is concluded that a reduction of alertness is not wholly responsible for the nystagmic reduction and that other factors, not yet identified, play a powerful role.