bluuebunny/crossref_metadata_2025 huggingface dataset:
Steroid effects on permeability of rat thymic lymphocytes to α-aminoisobutyrate
Authors: Blecher Melvin
Published: December 2017

In vitro studies of the flux of α-aminoisobutyrate-1-C14 (AIB) between rat thymic lymphocytes and extracellular fluid have revealed that: a) the amino acid enters cells but is not further metabolized; b) at low concentrations, similar to those of amino acids in plasma, the net influx and efflux of AIB exhibit properties of an active process; and c) influx of AIB is inhibited, and efflux stimulated, by deoxycorticosterone (DOC), by metabolic inhibitors, and by other specific steroids. In vivo studies of the distribution of AIB between serum and tissue demonstrated that administration of DOC to adrenalectomized rats inhibited concentration of AIB by thymus, diaphragm, and skeletal muscle, augmented uptake by liver, and increased the serum level of AIB. Prior adrenalectomy of donor rats resulted in no change from normal in the in vitro capacity of thymic lymphocytes to take up AIB. There was no significant difference from normal in the in vivo concentration of AIB by thymus, liver, and skeletal muscle of adrenalectomized rats, although uptake by diaphragm was decreased compared to normal control animals.
Measurement of blood volume in the fish (Salmo gairdneri gairdneri)
Authors: Conte Frank P. , Wagner Harry H. , Harris Thomas O.
Published: December 2017

The volume of blood in the steelhead trout ( Salmo gairdneri gairdneri) was determined by the simultaneous use of radioactively labeled human serum albumin (HSA-I131), Evans blue dye (T-1824), and radioactively labeled red blood cells (RBC-Cr51). Blood volume derived from the plasma-hematocrit method utilizing Evans blue dye = 3.5 ± 0.9; for labeled albumin = 3.3 ± 0.9; through simultaneous use of both dye and labeled albumin = 2.9 ± 0.9. Blood volume obtained directly through the sum of the plasma and packed red cell volumes as measured with either Evans blue dye or labeled albumin and tagged red blood cells = 2.8 ± 1.0. Values are expressed as per cent of body weight and are in agreement with those that have been reported in the literature for bony fishes (Osteichthyes).
Site of thrombin inactivation of the clearing factor system
Authors: Pilgeram L. O. , Amundson B.
Published: December 2017

A previous report has shown thrombin to markedly impair the activity of the human clearing factor system when triglyceride is used as the substrate. In an attempt to locate the site of the impairment, thrombin has been preincubated with selected, obligatory components of the clearing factor system. Subsequently the component is added to the enzyme system for activity assay. On this basis it has been possible to show that thrombin specifically destroys the lipoprotein lipase enzyme.
Developmental pattern of glucuronide formation in rat and guinea pig liver
Authors: Gartner Lawrence M. , Arias Irwin M.
Published: December 2017

o-Aminophenol (OAP) glucuronide formation by liver slices from fetal and newborn Wistar rats up to 70 hr old is equivalent to or greater than OAP glucuronide formation by liver slices from adult rats. OAP glucuronide formation by homogenates of liver from 3-day-old rats, and slices or homogenates of liver from 3-day-old guinea pigs is substantially less than that observed in comparable preparations of adult liver. These observations suggest that glucuronidation is deficient in newborn guinea pigs but not in newborn rats. Although the mechanisms responsible for these differences are unknown, the possibility is discussed that disruption of rat liver cells reduces glucuronide formation by activation of an inhibitor.
Specific alterations in sodium chloride intake after hypothalamic lesions in the rat
Authors: Covian Miguel R. , Antunes-Rodrigues José
Published: December 2017

Bilateral electrolytic lesions in the hypothalamus of the rat elicited either a decrease or increase in 2% NaCl intake, without a significant change in water ingestion. Lesions placed in the anterior hypothalamus involving supraoptic or paraventricular nuclei, or both, resulted in a conspicuous fall (as much as 93%) of NaCl intake. The decreased consumption remained to the end of the experiments which in some rats lasted 105 days and was accompanied by a decrease in NaCl urinary output. On the contrary, lesions placed in the central hypothalamus determined a specific increase of NaCl intake together with an augmented urinary excretion. The increased ingestion was permanent and lasted to the end of the experiment, attaining in one rat the value of 290%. To account for these results two provisional explanations are advanced, one of them considering the possibility of the existence of two areas of opposite effects regarding NaCl ingestion and the other claiming a neurohumoral mechanism in which oxytocin and aldosterone could be the two responsible hormones.
Blood clotting defect in hibernating ground squirrels (Citellus tridecemlineatus)
Authors: Lechler Eckhard , Penick George D.
Published: December 2017

In investigating the hypocoagulability of the blood during hibernation, multiple plasma-clotting factors, numbers of platelets, and hematocrits were determined in 17 hibernating 13-lined ground squirrels and compared with levels in 23 nonhibernating ground squirrels. Human plasma was used as the standard in procoagulant assays. At the time of withdrawal of the blood from the aortas of hibernating animals, their rectal temperatures ranged from 6.9 to 8.6 C. Significant differences between active and hibernating animals were found in the whole-blood clotting times (210 and 315 sec), partial thromboplastin times (45.5 and 109.3 sec), plasma prothrombin (443 and 698 U/ml), 1-hr serum residual prothrombin (27 and 449 U/ml), factor VIII (165 and 35%), factor IX (359 and 188%), and blood platelet concentration (445,150 and 47,940/mm3). No decisive changes were demonstrated in the prothrombin times or levels of factors V, VII, X, XI, XII, or fibrinogen. Inhibitors were not detected. Both thrombocytopenia and plasma defects seemed to contribute to the impairment of the blood-clotting mechanism during hibernation.
Twenty-four-hour collections of gastric content in spider monkeys
Authors: Brooks Frank P. , Ridley Peter , Attinger Francoise , Bjovedt George , Neff Kent
Published: December 2017

Hourly collections of fasting gastric content were made from six spider monkeys and two macaques with chronic gastric fistulae under conditions which allowed the animals free movement except during the collection period. A rise in pH was observed in 13 of 14 experiments after 6 pm while a return to a pH of 1–2 was seen in nine experiments between 7 and 8 AM the next morning. In two monkeys, each studied on three occasions, there was a significant decrease in volume and acid concentration coincident with the rise in pH. Pepsin concentrations did not change significantly. The electrolyte composition of samples with a pH of 7 or above and a chloride concentration of over 90 mEq/liter, was similar to that of the contents of a vagally-innervated pouch during the night except that the potassium concentration was twice as great in the fistula content. Pouch contents during feeding showed considerable acid secretion. The pH of the fasting gastric content of two macaques was greater than 3 over a 24-hr period.
Intracellular electrolyte patterns and transmembrane potentials of isolated atria
Authors: Peterson Nancy S. , Feigen George A.
Published: December 2017

Transmembrane potentials of electrically driven isolated guinea pig atria were recorded before and after three general types of manipulation of the external ionic environment: reduction of Na and Cl (sucrose substitution), reduction of Na but not Cl (choline chloride substitution), and reduction of Cl but not Na (NO3 substitution). Intracellular electrolyte patterns were determined under the same conditions. In all cases except extreme NO3 replacement there was little or no decline in resting potential, a moderate decrease in overshoot, and a reduction of the rate of depolarization. These changes were greatly exaggerated in the presence of high external [NO3]. Significant electrolyte shifts were an increase in [Na] i in approximate exchange for [K] i in the presence of NO3, and a loss of Cl i when choline chloride was substituted for NaCl. Attempts to predict the changes in resting potential from the analytical data by means of the constant-field equation gave adequate conformance in all cases but that of 100% NO3. The Nernst equation was applicable to the overshoot only in the reference solution.
Cell water, sodium, and potassium in red and white mammalian muscles
Authors: Sréter F. A. , Woo G.
Published: December 2017

Cell water, sodium, and potassium were determined in 12 different hind limb muscles and in the diaphragm of the rat to evaluate differences between white and red muscles. Red muscles (e.g., soleus, crureus, diaphragm) have a larger extracellular inulin space, higher [Na]i and lower [K]i than white muscles. Mixed muscles (e.g., gastrocnemius, rectus femoris) have intermediate values depending on the ratio of red and white fibers. The sum of intracellular [Na + K] is approximately the same in all muscles. There is no distinct demarcation between white and red fibers in mixed muscles. Histological observations revealed that the terms "red" and "white" as applied to the whole muscle do not imply homogeneity of the component fibers. Moreover, the distribution of the red and white fibers was not uniform in any of the hind-limb muscles examined.
Utilization of cystine-S35 by the chick embryo
Authors: Johnston P. M. , Harvey J. A. N.
Published: December 2017

Fertile eggs from controlled flocks were injected with 10 µc l-cystine-S35 (specific activity 5.71 µc/µmole) and incubated under standard conditions of humidity, circulation, and temperature. Beginning with the 5th day, embryos were hydrolyzed (6 N HCl, 6 hr, 15 lb) and chromatographed using ascending strip chromatography. Cystine and methionine were determined colorimetrically following elution; radioactive assay was done on the eluates; and the specific activity of both cystine and methionine was determined. The specific activity of cystine at 5 days was .0092 and increased generally until the 20th day (.0692). The specific activity of methionine at 9 days was .0104, at 16 days was .0490, and at 20 days was .0132. The per cent of the dose recovered as cystine at 20 days was 22.21 and that recovered as methionine was 2.03. The data for specific activity indicate that the fractional composition of embryonic protein relative to cystine and methionine is not constant and that there is considerable sulfur transfer between cystine and methionine.
Production of diabetes mellitus in the duck by insulin antibodies
Authors: Mirsky I. Arthur , Jinks Robert , Perisutti Gladys
Published: December 2017

The intravenous injection of anti-insulin serum produces an immediate increase in the blood glucose concentration of both normal and presumably "depancreatized" ducks. Whereas the blood glucose of the normal ducks returns to the preinjection concentration within 3.5 hr, the hyperglycemia of the depancreatized ducks persists for more than 5 hr. The response is attributed to an acute insulin insufficiency induced by insulin antibodies. Accordingly, insulin is as essential to the regulation of the blood glucose of the duck as it is to that of mammals. The data from depancreatized ducks suggest the presence of a remnant of splenic lobe of the pancreas or some extrapancreatic source of insulin.
Lipolytic action of epinephrine in adipose tissue homogenates
Authors: Rubinstein David , Chiu Sylvester , Naylor Jean , Beck John C.
Published: December 2017

Incubation of intact adipose tissue with ACTH, certain preparations of growth hormone, and epinephrine induces an increase in lipolytic activity in homogenates prepared from this tissue. Epinephrine also causes an increase in lipolytic activity when added directly to adipose tissue homogenates. The increase is inhibited by 4 x 10–4 m iodoacetate. Mitochondrial and "supernatant" fractions (including microsomes) and the lipid layer all possess lipase activity, but only the lipase found in the supernatant fraction can be activated by epinephrine. Protamine activates this lipase; addition of epinephrine has no additive effect. Heparin inhibits the stimulation of lipase activity by epinephrine, but has no action on the lipolysis occurring in the absence of epinephrine. It is concluded that the epinephrine-stimulated lipase is distinct from lipoprotein lipase and the lipase present in unstimulated tissue.
Effect of growth hormone of free fatty acid metabolism
Authors: Winkler Bertram , Steele Robert , Altszuler Norman , de Bodo Richard C.
Published: December 2017

Bovine growth hormone ( GH) was administered at 1 mg/kg day for various periods of time to normal dogs. The effects produced on plasma free fatty acid ( FFA) metabolism were studied in these animals, in the unanesthetized state, using palmitate-C14. At 3–9 hr following intravenous injection of growth hormone significant increase were observed in plasma FFA concentration, turnover rate, total amount of FFA oxidized to CO2, and per cent of total respiratory CO2 derived from FFA. FFA production was increased by GH; FFA uptake and oxidation increased in parallel with plasma FFA concentration and apparently were not affected directly by GH. Similar changes were observed after 2 days of GH. After 7 days of GH all these parameters returned to control values. The transient effect of GH on FFA metabolism is in contrast with its reported prolonged effects on fat metabolism; possible reasons for this discrepancy are discussed.
Placental transfer of nitrofurantoin and furaltadone
Authors: Buzard James A. , Conklin John D.
Published: December 2017

The placental transfer of nitrofurantoin and furaltadone was determined in the guinea pig, rabbit, dog, and sheep. Both compounds entered the fetal circulation of the dog to a greater extent than in the other species, and furaltadone consistently crossed the placenta more readily than nitrofurantoin in all species. On the basis of these results, it is suggested that the transplacental movement of drugs is determined by both the physical characteristics of the drug and the morphohistologic structure of the placenta.
Magnesium and calcium as regulators of intestinal permeability
Authors: Tidball C. S.
Published: December 2017

The absorption of phenolsulfonphthalein (phenol red) was used as a measure of intestinal permeability in rats anesthetized with sodium pentobarbital. All solutions placed in the intestinal lumen were adjusted to pH 7.0 and 300 mosmoles/liter. When 5 ml of a 1 mm solution of phenol red were placed in either proximal or distal halves of the small intestine the mean hourly absorption was 1.1%. The presence of 25 mm/liter ethylenediaminetetraacetate (EDTA) as the calcium salt did not alter phenol red absorption. With 25 mm/liter NaEDTA in the lumen, the absorption of phenol red was increased tenfold. After NaEDTA had been present for 1 hr, rinsing the lumen produced results which varied with the ionic composition of the rinsing solution. Balanced physiologic saline did not reverse the increased permeability. A CaCl2 rinse produced a permeability intermediate between NaEDTA and control levels. A MgCI2 rinse reinstated normal permeability. It is concluded that magnesium and calcium, loosely bound in the structure of the membrane, regulate the aqueous permeability of the intestinal epithelium.
Ventricular performance, pressure-volume relationships, and O2 consumption during hypothermia
Authors: Monroe R. G. , Strang R. H. , LaFarge C. G. , Levy J.
Published: December 2017

Left ventricular performance in the isolated heart of a dog was observed at normal temperatures (37.7 C) and under hypothermia (32.2 C) at comparable heart rates. The peak pressure of isovolumic contractions at the same ventricular end-diastolic pressures averaged 40% higher at the lower temperature. Diastolic pressure-volume relationships were similar at both temperatures. In studies in which the ventricle ejected fluid and performed work the hypothermic ventricle was capable of performing greater work at comparable heart rates, left ventricular end-diastolic pressures, and loading. When the ventricle was allowed to perform work by compressing air into a chamber of constant volume left ventricular oxygen consumption (Vo2) increased with the peak systolic pressure as the temperature was lowered. If the peak systolic pressure was maintained constant by increasing the volume of the air chamber as the temperature was lowered no consistent relationship could be shown between left ventricular Vo2 and the integral of systolic pressure in time which invariably increased with hypothermia.
Sodium and potassium flux of separated renal tubules
Authors: Burg Maurice B. , Grollman Evelyn F. , Orloff Jack
Published: December 2017

The Na and K fluxes of renal tubule cells were measured using suspensions of tubules separated from rabbit renal cortex. Kinetic analysis indicates that there are at least two Na compartments and two K compartments in the tubules. The rates at which Na and K exchanged were considerably greater than in renal cortical slices in accordance with predictions based on considerations of the geometrical arrangement of the cells in slices. Digitalis-like steroids, known to depress active cation transport, lowered the efflux rate constant for Na from the major Na compartment and diminished both K influx and the K efflux rate constants. The calculated active efflux of Na greatly exceeded the influx of K, indicating that active Na and K transport are not coupled in a 1:1 ratio.
Angiotensin blood levels in hemorrhagic hypotension and other related conditions
Authors: Scornik Oscar A. , Paladini Alejandro C.
Published: December 2017

Angiotensin blood levels were measured in anesthetized dogs under different experimental conditions. In hemorrhagic hypotension, a marked and progressive increase in angiotensin blood levels was detected. No increase was found when a similar reduction in renal perfusion pressure was elicited by constriction of the aorta above the renal arteries. A high dose of norepinephrine infused simultaneously with the constriction of the aorta produced a significant increase in angiotensin blood levels which was lower than the one detected after hemorrhage. A potentiation of the effect of dog renin injections on angiotensin blood levels by bleeding was shown. It is concluded that the rise in angiotensin blood levels after hemorrhage is not solely due to a decreased renal perfusion pressure. Other possibilities are discussed.
Biotin transport by small intestine of rat, hamster, and other species
Authors: Spencer Richard P. , Brody Kenneth R.
Published: December 2017

At a concentration of 1 x 10–5 m, biotin-H3 and biotin-C14 were transported against a concentration gradient by hamster everted intestinal sacs. Similar transport was shown by the small intestine of the white mouse, Mongolian gerbil, chinchilla, flying squirrel, round-tail squirrel, Malayan black squirrel, and chipmunk (and was maximal in the chipmunk intestine). Transport under these conditions was not shown by the small intestine of the rat, rabbit, guinea pig, ferret, or carp. There does not appear to be a correlation between the need for biotin as a vitamin in a species and the presence of this transport system. Chromatography of the mucosal and serosal solutions did not reveal any radioactive spot other than the original biotin-H3 or biotin-C14. This evidence, plus the inhibition of transport by avidin, suggests that it is biotin that is being transported, and not a metabolite. The unidirectional flux of biotin (from a side containing the vitamin to a side which did not), was uninfluenced by the addition of avidin to the buffer into which diffusion was occurring. The "apparent Km" for biotin transport was on the order of 6 x 10–5 m, based on equilibrium measurements. Transport of biotin in the hamster small intestine occurred principally in the first one-third to one-half of the small intestine. Amino acids, urea, biotin- d-sulfoxide, as well as biotin- l-sulfoxide did not inhibit biotin transport. Biocytin, biotin methyl ester, diaminobiotin, desthiobiotin, thioctic acid, and two other analogues inhibited biotin transport.
Measurement of short-circuit current and ion transport across the ileum
Authors: Clarkson T. W. , Toole S. R.
Published: December 2017

An apparatus is described which allowed control over both the electrical and chemical potential gradients across the isolated ileum of the rat and at the same time permitted the measurement of the transport of ions and water. Silver ions, released from the electrodes, affected ion transport. In the absence of complexing agents, the short-circuit current ( SCC) fell during the 60-min measurement period and was equal to the net sodium transport. With 10–3 m reduced glutathione in the bathing solution, the SCC was constant and equal to 94% of the sodium transport. With 10–4 m cysteine, the SCC was greatly increased. Sodium transport, also increased, was equal to 75% and chloride secretion to 20% of the SCC. A mechanism by which silver ions stimulate sodium transport, is proposed. Comparison of water and salt transport between open- and short-circuited tissues indicated that chloride ions were more effective in producing water movement when transported from mucosal to serosal solutions directly through the tissue (open circuit) rather than via the Ag/AgCl electrode system (short-circuit experiments).
Anemia in rats on atherogenic diets
Authors: Wohl Herbert , Merskey Clarence
Published: December 2017

Rats were fed atherogenic diets containing cholesterol (5%), thiouracil (0.3%), and cholic acid (2%). One diet also contained 40% beef fat. Controls were fed chow with 10% peanut oil. Hemoglobin and hematocrit levels in rats fed atherogenic diets rose initially, then fell progressively. At 60 days the hemoglobin levels were 1.5 g/100 ml less and hematocrit levels 8% less than in controls. Added fat diets also induced diarrhea, dermatitis, and weight loss. Survival of Cr51-labeled red cells from rats on atherogenic diets was shortened whether the cells were injected into controls or into other rats on atherogenic diets. Red cells from controls survived normally in rats fed any of the diets. Despite normal pyridoxine intake, urinary xanthurenic acid excretion after a tryptophane load was elevated in rats fed either atherogenic diets or a normal control diet in restricted amounts. It is concluded that an intrinsic red cell abnormality develops in rats fed atherogenic diets. The abnormal tryptophane metabolism may be due to deficiencies related to underfeeding.
Prolonged trophic effects of vagal innervation on diaphragm
Authors: Jefferson N. C. , Ogawa T. , Kuroyanagi Y. , Geisel T. , Toman J. , Necheles H.
Published: December 2017

It has been shown that if the proximal end of a cut vagus nerve is anastomosed to the distal end of a cut phrenic nerve, the musculature of the hemidiaphragm is preserved, although inactive; it contracts upon direct stimulation and, also, upon stimulation of the vagus nerve above its anastomosis. These observations lasted for 22.7–31.5 months and confirm previous work which was of shorter duration. Thus, it is demonstrated that preservation of structure of muscle by innervation by a "foreign" nerve may last, perhaps indefinitely, in the absence of the normal respiratory motion of the hemidiaphragm.
An electrophysiological study of taste reception in peripheral nerves of the calf
Authors: Bernard Rudy A.
Published: December 2017

Multiunit neural activity was recorded from gustatory nerves of 28 calves following chemical and mechanical stimulation of the tongue. The chorda tympani nerve was found to have a posterior, in addition to the classical anterior, receptive field. The anterior field responded to NaCl and acetic acid, starting at 0.001 m, and KCl and propionic acid, starting at 0.01 m. Fructose, glucose, xylose, and sucrose had higher thresholds and were less effective than equimolar concentrations of the salts and acids studied. Quinine sulfate, Na saccharin, distilled H2O, and mechanical stimulation produced small responses. In contrast, the posterior field yielded large responses to distilled H2O and to mechanical stimulation. Many of the same chemical stimuli were effective, but had different response characteristics. In relation to NaCl, acetic acid was more effective on the posterior than the anterior field. On the receptive field of the glossopharyngeal nerve mechanical stimulation was more effective than chemical stimulation, which produced small responses from high stimulus concentrations. The behavioral taste responses of bovines are compared with the electrophysiological data.
Effect of acetazolamide on citrate excretion in the dog
Authors: Simpson David P.
Published: December 2017

Clearance measurements were made on dogs in order to study the mechanism of the effect of acetazolamide on citrate excretion. Induction of metabolic alkalosis resulted in a marked rise in citrate clearance despite treatment with acetazolamide. Measurement of citrate clearances in alkalotic animals before and after acetazolamide infusion showed either no change or an increase in citrate clearance. No evidence was found that acetazolamide decreases citrate excretion when acidosis is prevented. These results are consistent with the hypothesis that changes in citrate clearance after acetazolamide administration are entirely secondary to changes in acid-base balance.
Evidence of injury by heat in mammalian tissues
Authors: Burger F. J. , Fuhrman Frederick A.
Published: December 2017

Some possible criteria of injury by heat were investigated using slices of rat liver, cerebral cortex, and renal cortex heated in vitro. The following were measured at approximately 1-C intervals between 40 and 47.5 C, and in each case the results were compared with controls incubated for the same time at 38 C: Qo2, the increase of ammonia, urea, cholesterol, and acid phosphatase in the suspension medium, and the leakage of Rb86 from tissues labeled with this isotope in vivo. In general, deviation from the control at a given temperature increased with time. For a given tissue, several or all of these deviated from the control at about the same temperature. For cerebral cortex this was about 43 C and for liver about 45 C. The most sensitive indicator of injury appeared to be the accumulation of ammonia in the medium, and this deviated from controls at 40 C for renal cortex and 42 C for liver and cerebral cortex. Thus, there is evidence for several biochemical changes produced by heating in vitro to temperatures at or below those at which irreversible changes occur in vivo.
Specificity of corticotrophin-induced increase in mitochondrial ribonucleic acid
Authors: Sigel Morton B. , Dowling J. Thomas
Published: December 2017

Ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) were measured in subcellular fractions of pooled adrenals removed from rats 4 hr after injection of agents known to affect or suspected of altering adrenal intermediary metabolism. Corticotrophin (2 µ) increased mitochondrial RNA 29% over that of saline-injected animals and 74% over uninjected controls. Nuclear DNA and nuclear and microsomal RNA were unchanged. Thyrotrophin (2 µ), growth hormone (1 µ), chorionic gonadotrophin (500 µ), triiodothyronine (25 µg), p-dinitrophenol (50 µg), crude parathyroid hormone (10 µ), and vasopressin (0.4 µ) failed to affect either nucleic acid. The mitochondrial-adrenal weight ratio increased only in corticotrophin-treated animals. The percentage increase of mitochondrial RNA exceeded that of mitochondrial weight. Conjugated estrogen was the only other agent that produced a response. One, five, and ten micrograms increased DNA in spayed female rats while 50 µg produced no effect. Estrogen presumably affected cell division. A part of the sequential response of adrenal intermediary metabolism to corticotrophin includes a specific increase in the nucleic acid content of that organelle associated anatomically with steroidogenesis.
Permeability of mammalian heart capillaries to sucrose and inulin
Authors: Schafer David E. , Johnson John A.
Published: December 2017

Rabbit hearts were perfused with modified Ringer's solution containing 10 g sucrose or inulin per liter. After various perfusion times, ventricular samples were analyzed for their content of the respective saccharide. The tissue content of sucrose rose to half its apparent maximum value in approximately 6 sec; the corresponding time for inulin was approximately 90 sec. We concluded that at the high perfusion rates employed (40 ml/min per heart) inulin permeation is limited by passage across the capillary membrane and is practically unaffected by perfusion rate and interstitial diffusion, while sucrose permeation is limited partly by passage across the capillary membrane and partly by perfusion rate. We calculated capillary permeability coefficients of 0.4 x 10–5 cm/sec for inulin and 11 x 10–5 cm/sec for sucrose.
Mechanism and significance of endotoxin-induced sensitization to acetylcholine in rabbits
Authors: Hildebrand G. J. , Seys Y.
Published: December 2017

An earlier report described a sensitization of pulmonary vasoconstrictor mechanisms (PVM) to circulating acetylcholine (ACh) in rabbits injected with Pseudomonas pseudomallei endotoxin. Preliminary studies showed that the sensitization was induced also by endotoxin from other gram-negative bacilli. The mechanism of sensitization and its significance are analyzed in this study. The effect was specific for ACh, unaltered by elimination of reflex mechanisms, and could be obtained in heart-lung preparations. Antihistaminic and adrenergic blocking agents did not abolish the phenomenon. Sensitization to ACh was not attributed to ACh-esterase inhibition. Atropine reduced or eliminated the enhanced responses to ACh after endotoxin but had no effect on the progressive fall in systemic arterial pressure to shock levels or on the lethality of endotoxin. It was concluded that endotoxin-induced sensitization of PVM to circulating ACh did not play a major role in endotoxin shock.
Lack of enhanced lysis of fibrinogen-I131 by anticoagulants in tumor-bearing rats
Authors: Shaeffer Joseph R.
Published: December 2017

The effect of heparin and warfarin on the catabolism of fibrinogen-I131 in rats bearing a fibrinogen-localizing tumor, the Murphy-Sturm lymphosarcoma, was studied. These anticoagulants have been shown previously to depress fibrinogen-I131 localization in the tumor by 80%. In the present work whole-body and blood retentions of I131 18 hr after intravenous injection of fibrinogen-I131 were found to be the same or increased in rats receiving anticoagulants compared to the controls. The blood plasma radioactivity was found to be 90–95% clottable in both experimental and control groups. There were found no significant differences in I131 concentration of iodide-trapping organs or of many normal visceral organs. Only in the edematous skin and muscle surrounding the solid tumor was there found an increase in I131 concentration in rats receiving anticoagulants. Radioactivity eluted from this tissue was 80–85% clottable. Because of this lack of enhanced breakdown of fibrinogen-I131 by anticoagulants, it was concluded that heparin and warfarin probably did not inhibit tumor localization of fibrinogen-I131 by a profibrinolytic mechanism.
Spinal fluid iodide transport in the dog
Authors: Coben Lawrence A. , Loeffler John D. , Elsasser James C.
Published: December 2017

A technique has been developed for study of the transfer of radioiodide after injection into the ventricular spinal fluid in the anesthetized dog. I131 moves rapidly from spinal fluid to blood after intraventricular injection of a trace dose. Disappearance of I131 as measured over the head after intraventricular injection of a trace dose follows a curve suggesting the presence of multiple processes. The effects of pretreatment with intraperitoneal perchlorate or unlabeled sodium iodide have been studied. Perchlorate increases transport from blood to spinal fluid and decreases it in the opposite direction. Unlabeled iodide slows transport from spinal fluid to blood only above certain dose levels. The "barrier" to movement of iodide from blood to spinal fluid is thus probably due to transport of iodide from ventricular spinal fluid to blood, rather than to a semipermeable membrane hindering movement into spinal fluid. The properties of the transport system for I131 imply possible use in the study of spinal fluid dynamics.
Intestinal absorption of bile salts in the rat
Authors: Holt Peter R.
Published: December 2017

Studies of taurocholate and cholate-C14 absorption by slices of rat intestine reveal that an active absorptive mechanism obeying Michaelis-Menten kinetics is present in the ileum but absent in other portions of the gut. Following 1 day of bile duct cannulation, the in vitro absorption of bile salts was enhanced two- to three-fold. The normal tissue concentration of bile salts in the ileum reached 1.3 µm and in the jejunum 0.35 µm/g tissue water. The presence of endogenous bile salts resulted in inhibition of subsequent ileal active absorption competitively suggesting the existence of a common receptor site for mucosal bile salt absorption. Active absorption was dependent on sodium concentration and inhibited by potassium. The significance of these results is discussed.
Vascular manifestations of extensive thermal skin injury in rat mesentery
Authors: Horn Leif , Malm Ole J.
Published: December 2017

After 40% body surface area skin burns, mesenteric microcirculation revealed initially augmented vasomotion and increased epinephrine responsiveness. Lowered precapillary epinephrine thresholds persisted throughout the terminal phase of early fatalities. Animals surviving 48 hr went through a phase with elevated epinephrine thresholds. Venodilatation coexisted with precapillary constriction. Initially most capillaries were empty; a few were dilated and congested with sluggish blood flow, indicating stasis. Lowered epinephrine responsiveness appeared first on the venous side coincident with apparent relief of stasis. Whitish aggregates or "clots" were frequently observed in circulation, but sludging or red cell agglutination was virtually absent. Morphologically the small blood vessels revealed endothelial swelling and there was a tendency for leukocytes to adhere to the vessel wall, the latter feature being more pronounced in later stages of burn shock. Other hemodynamic data indicated general peripheral vasoconstriction which gradually subsided in recovering animals. The circulatory changes are not consistent with circulating "burn toxins" impairing vascular contractility but with disruption of local control of vascular smooth muscle responsiveness, resulting in decompensatory venodilatation.
Areas under thermal-dilution curves, assuming log-normal distribution
Authors: Lewi Paul
Published: December 2017

Graphical methods are described for the calculation of areas under dilution curves. Replotting of the original curve and subsequent planimetry can be avoided by assuming log-normal distribution of the transit times. The validity of the assumption is indicated. Relative accuracies of the proposed methods are discussed. A comparison is drawn between the log-normal assumption and the negative exponential law of Hamilton, and a systematic deviation between the procedures is observed for higher values of the cardiac output. The log-normal assumption has a trend to yield higher values for the cardiac output than the classical method of Hamilton.
Functional development of active sugar transport in the chick intestine
Authors: Bogner Phyllis Holt , Haines I. Ann
Published: December 2017

The intestinal sugar transport function of late embryos and young chicks was studied by means of the tissue-accumulation method. Penetration of intestinal slices by sorbose was minimal in all age groups, ranging between 0.2 and 6.0 µmoles/g dry wt. The ratio of sorbose concentration in tissue water to that in the final medium (T/M) never exceeded 0.3. Galactose uptake by embryonic intestine was comparable to that for sorbose. In contrast, 0-day-old slices accumulated 29 µmoles galactose/g dry wt. which gave a T/M of 3.7. Maximal concentrative power was exhibited by 2-day-old slices which accumulated 38 µmoles galactose/g dry wt., resulting in a T/M of 7.4. Mutual inhibition of active transport between glucose and galactose was observed in 2-day-old slices. In intact chicks alimentary absorption rates of these two sugars rose sharply and to about the same extent between 0 and 2 days of age. Hence both in vitro and in vivo evidence suggests that an active transport process for sugars becomes functional in the chick intestine during the hatching period.
A micropuncture evaluation of renal ammonia excretion in the rat
Authors: Hayes Charles P. , Mayson James S. , Owen Edward E. , Robinson Roscoe R.
Published: December 2017

Measurements of ammonia and inulin concentration were performed on samples of proximal or distal tubular fluid from 46 diuretic rats, some of which were pretreated with oral ammonium chloride. During mannitol diuresis alone, the ammonia concentration of midproximal tubular fluid averaged .77 ± .46 mm, while that of distal tubular fluid averaged 3.2 ± 1.1 mm. Midproximal ammonia was sufficient to account for as much as 62–70% of urine ammonia, while the distal tubular ammonia concentration theoretically provided 93–114%. After chronic ammonium chloride administration, the midproximal ammonia concentration rose to 1.5 ± .8 mm, while that of distal tubular fluid equaled 5.29 ± 1.3 mm. Net ammonia addition to collecting duct fluid was not obtained in either normal or acidotic rats. These observations demonstrate that the proximal tubule is an important potential source of final urine ammonia, and that increased proximal ammonia addition also occurs in response to chronic ammonium chloride acidosis. Although distal tubular ammonia addition probably occurs also, definite statements cannot be made regarding its magnitude in either normal or acidotic rats. However, it is apparent that the collecting duct is not an important source of final urine ammonia.
Relationship of maximal tubular phosphate reabsorption to dietary phosphate in the dog
Authors: Hellman Dorothea , Baird H. Robert , Bartter Frederic C.
Published: December 2017

In normal dogs, the maximal tubular reabsorption of phosphate (Tmp) on moderate phosphate (P) intake has been compared to that on high P intake. Oral P loading caused a reduction in glomerular filtration rate (GFR) in all the animals. A significant reduction in Tmp could be demonstrated in five of the six dogs while on sustained oral P loading. This decline in Tmp was significantly greater than could be accounted for by the regression of Tmp on GFR. A return toward normal values for TmP occurred following resumption of a normal diet. The reduction in Tmp during oral P loading suggests that a reduction in renal tubular reabsorption of phosphate (TRP) is one means whereby excess phosphate is eliminated from the body. This reduction in TRP may be related to an increased release of endogenous parathyroid hormone.
Food intake and temperature regulation in rats with rostral hypothalamic lesions
Authors: Hamilton C. L. , Brobeck John R.
Published: December 2017

Rats with lesions of the anterior midline hypothalamus were studied in reference to the regulation of body temperature and food intake. The data support the thesis that this area of the hypothalamus is involved not only with normal regulation of body temperature but also with food intake, and thus indirectly with internal heat production.
Supraspinal inhibition of a cutaneous vascular reflex in the cat
Authors: Prout B. J. , Coote J. H. , Downman C. B. B.
Published: December 2017

In cats anesthetized with chloralose-urethane mixture, stimulation of an afferent nerve evoked a vasoconstrictor reflex (VCR) and a galvanic skin response (GSR) in the pads of the feet. Stimulation of the ventromedial medullary reticular substance at the level of the obex abolished the VCR and the GSR. VCR could also be reduced by occlusion during prolonged stimulation of another spinal or visceral afferent pathway. Medulla stimulation was effective without itself causing a sympathetic discharge to the paw, showing that inhibition rather than occlusion was operative. Anterior cerebellar stimulation also inhibited the VCR. Carotid sinus nerve stimulation did not abolish the VCR. It is concluded that the effective mechanism includes a bulbospinal inhibitory path projecting on a spinal vasoconstrictor reflex arc. This arrangement is similar to the descending pathways inhibiting other spinal reflexes but the VCR-inhibitory path can be activated independently of them.
Electrolyte and water distribution in the heart in irreversible hemorrhagic shock
Authors: Coleman Bernell , Glaviano Vincent V.
Published: December 2017

Electrolyte and water content were determined in left ventricular muscle in control dogs and dogs subjected to irreversible hemorrhagic shock. In shock, myocardial potassium increased from 39.6 to 47.7 mEq/100 g fat-free dry tissue, while sodium decreased from 16.4 to 13.2 mEq/100 g fat-free dry tissue. Water content, as well as levels of magnesium, calcium, and chloride were not significantly altered. Changes of intracellular potassium, sodium, magnesium, and calcium were within limits expected from Gibbs-Donnan equilibrium relationships. However, interstitial potassium and magnesium were markedly elevated from 4.56 to 7.52 mEq/kg and from 1.29 to 2.54 mEq/kg, respectively. As a result of the increase in interstitial potassium, the calculated average resting membrane potential differed by 11 mv from control dogs. The observed alterations in myocardial electrolytes in our shock experiments are not similar to those generally encountered in heart failure. On this basis, a cardiac factor may not be a major cause of the irreversible state of hemorrhagic shock.
An experimental and theoretical analysis of myocardial tissue pressure
Authors: Kirk Edward S. , Honig Carl R.
Published: December 2017

A new technique for estimating myocardial tissue pressure is described. The method is based upon changes in flow through an analog of a small coronary vessel. A gradient of tissue pressure from epicardium to endocardium was observed with peak tissue pressures twice peak ventricular pressure recorded in the inner half of the wall. A theoretical analysis of the concept of intramyocardial pressure is presented, based on the assumption that the tissue is a solid within which both longitudinal and radial compressive forces exist. The similarity between the gradient of longitudinal tissue pressure predicted by the theoretical analysis and the gradient experimentally determined suggests that the latter describes the maximum pressures which exist in the left ventricular wall.
Metabolic disturbances and short-circuit current across intestinal wall of rat
Authors: Asano Tomoaki
Published: December 2017

The potential difference, short-circuit current, and resistance were determined across the wall of the rat small intestine under a variety of conditions in vitro. With the normal Ringer's fluid on both sides of the wall, the average values obtained were 7.6 mv for the potential difference, 120 µa/cm2 for the short-circuit current, and 63 ohm-cm2 for the resistance. The potential difference and short-circuit current were found to vary roughly in parallel except upon application of low Na concentration. Reversible reduction was induced in both potential difference and short-circuit current by 1 mm sodium azide, 0.1 mm phlorizin, and 0.1 mm dinitrophenol applied on the mucosal side. Withdrawal of glucose from the mucosal side induced a decline of both potential difference and short-circuit current, and the decline was partially recovered by substitution of galactose for glucose at the same concentration but not of fructose or sorbitol. The short-circuit current was shown to depend upon the glucose concentration on the mucosal side in accordance with Michaelis-Menten kinetics, the Km value being 72 mg/100 ml. On the other hand the short-circuit current was linearly related to the Na concentration in Ringer's fluid. At low concentration of Na the resistance increased more than could be accounted for by the decrease of conductivity of low Na Ringer's fluid.
Alloxan distribution (in vitro) between cells and extracellular fluid
Authors: Watkins Dudley , Cooperstein S. J. , Lazarow Arnold
Published: December 2017

The distribution of alloxan added to toadfish tissues in vitro was studied under conditions in which the rate of alloxan decomposition was markedly reduced (0 C, pH 7.0). When washed red blood cells were added to alloxan solutions of varying tonicities, the amount of swelling corresponded to that obtained with equivalent solutions of saline or phosphate; therefore alloxan behaved like a nonpenetrating solute. Alloxan-2-C14 (tracer doses) was added to blood, and the cells and serum were subsequently separated; the amount of radioactivity in the packed cell mass was identical to that found with d-mannitol-1-C14, but was far less than that obtained with urea-C14. Similarly, when toadfish islet slices were incubated in a mixture of alloxan-2-C14 plus d-mannitol-1-H3, the proportion of the two isotopes found within the tissue was the same as that in the medium. These results indicate that alloxan, like mannitol, does not enter the cells but remains in the extracellular fluid; they thereby support the thesis that the primary site of alloxan action is at the ß-cell membrane.
Rat mammary gland metabolism relative to epithelial and connective tissue content
Authors: Rees E. Douglas , Eversole Amy
Published: December 2017

The respiration rate of rat mammary gland slices increased directly with the epithelial proliferation induced by pregnancy and lactation. In the absence of glucose the respiration was depressed, particularly in slices with the largest epithelial content. Dinitrophenol (5 x 10–5 m) provided a metabolic distinction between the epithelium of pregnant and lactating mammary glands; it stimulated the respiration of the former and depressed the respiration of the latter. The rate of anaerobic glycolysis (q1acN2) for mammary epithelium was adduced to be 4–5 µl/hr mg dry nonfat tissue and the rate remained in that range during lactation and pregnancy; the rate of aerobic glycolysis increased during pregnancy and decreased during lactation. Alkaline phosphatase activity did not vary directly with the mammary epithelium content and it was suggested that the rate of epithelial cell proliferation (mitoses) and hormonal factors might also be of importance in determining the total activity observed. The increase in glucose 6-phosphate dehydrogenase and 6-phosphogluconic acid dehydrogenase activity during pregnancy and at the onset of lactation was not directly related to the increase in mammary epithelium.
Weak electrotonic interaction between contiguous cardiac cells
Authors: Tarr Merrill , Sperelakis Nick
Published: December 2017

Electrotonic spread of current was studied by double microelectrodes cemented at various distances. A bridge circuit enabled transmembrane potentials to be recorded at zero distance from injected current. At interelectrode distances of 60 µ or greater, current flow of 16 x 10–9 amp through one intracellular electrode produced no change in potential at the second electrode. At interelectrode distances of 45 µ or less, similar currents through a given electrode pair produced either a substantial or no change in potential depending on the impalement. Various criteria, including simultaneous subthreshold oscillations, indicated when both electrodes impaled the same cell. The degree of electrotonic spread did not increase during the plateau of the action potential and did not depend on the interelectrode distance per se at close interelectrode distances. Thus, current flow through one cell does not have substantial effect on the membrane potentials of adjacent cells; hence the intercalated discs may be high resistance.