bluuebunny/crossref_metadata_2025 huggingface dataset:
Action of Tetraethylammonium Chloride on Neuromuscular Transmission in Frogs
Authors: Koketsu Kyozo
Published: December 2017

The action of tetraethylammonium chloride (TEA-Cl) on the neuromuscular transmission in frogs of 0.2–3 mm concentration was analyzed by recording a) the mechanical responses; b) direct action on the muscle fibers; c) end-plate potential (e.p.p.); d) direct action on the end-plate membrane; e) sensitivity of end-plate membrane to the applied ACh; f) the action potential of terminal endings of motor nerve fibers; g) direct action of nerve axon. TEA-Cl in these concentrations augments the e.p.p., and this augmentation increases with increasing concentrations. A relatively higher concentration (1–3 mm) depresses the e.p.p. after an initial augmentation. The sensitivity of the end-plate membrane to ACh is depressed by 0.2–3 mm. TEA-Cl in these concentrations acts on the terminal endings of motor nerve fibers and prolongs the negative after-potential of terminal endings. It is suggested that TEA-Cl increases the release of ACh by acting on the terminal endings, thus causing the augmentation of e.p.p.'s. The action of TEA-Cl at a given concentration will be determined by separate actions both on the end-plate membrane and the terminal ending of motor nerve fibers.
Nonconcentration of Thiocyanate-C14 by the Thyroid Gland of the Mouse
Authors: Wollman Seymour H. , Reid James C. , Reed Franklin E.
Published: December 2017

After administration of C14-labeled thiocyanate, the concentration of C14 in the thyroid gland following equilibration was about half that in the serum of normal and hypophysectomized C3H mice. Paper chromatography of the serum revealed that 90% of the C14 was in the form of thiocyanate. These results, coupled with a previous analysis which indicated that thiocyanate competitively inhibited the thyroid iodide concentrating mechanism, appear to eliminate the possibility that concentrated iodide is held in the thyroid by adsorption.
Pressures in Umbilical Arteries and Veins of the Fetal Lamb in Utero
Authors: Reynolds S. R. M. , Paul W. M.
Published: December 2017

During the last third of gestation in the ewe (149 days), the first branch of an umbilical artery and of an umbilical vein was catheterized. Access was obtained by going through a small opening in the uterus to the vessels, leaving the membranes intact. Blood pressures in the main artery and vein were recorded, along with carotid blood pressure and respiratory activity in the ewe. Normal venous pressures were 20–35 mm Hg; arterial pressures, 50–70 mm Hg. The pressure gradient across the placenta, 10–20 mm Hg. Arterial and venous pulsations have been observed, most often synchronous, but at times out of phase. Pressure on the uterine contents by strong respiratory movements or use of Pitocin have caused equal rises of pressure in arteries and veins. When mild and severe hypoxia occur in the ewe (10–13% O2 and 6% O2 in the inspired air), changes in blood pressure occur, but more commonly in the artery than in the vein. Venous pressure falls with terminal hypoxia, indicating a failure of cardiac output. Venous pressure has been seen to remain near normal levels even though heart rate increases or decreases and even though arterial pressure go up or down. When umbilical vein pressure fails, however, fetal death is imminent.
Membrane Conductance and Current-Voltage Relation in the Squid Axon Under ‘Voltage-Clamp’
Authors: Tasaki I. , Spyropoulos C. S.
Published: December 2017

The conductance of the squid axon membrane under ‘voltage-clamp’ was measured by superposing a sinusoidal wave upon rectangular clamping voltage pulses. It was possible to determine the time course of the emf of the membrane under ‘voltage-clamp’ on a single photographic record showing the membrane current together with the simultaneously recorded membrane conductance. The properties of the membrane in the mixed state, in which only a portion of the axon membrane is in the excited state, were investigated by the same method. The property of the weak variable inward membrane current which preceded the appearance of discrete inward surges was investigated.
Adrenocortical Activity in Hypophysectomized Dogs
Authors: Eik-Nes Kristen , Brizzee Kenneth R.
Published: December 2017

The pituitary gland was removed in normal mongrel dogs. Following this operation low or zero plasma levels of 17-hydroxycorticosteroids (17-OHCS) were seen as early as 12 hours postoperatively. Dogs completely hypophysectomized from 15 to 30 days exhibited no increase in plasma 17-OHCS subsequent to the ‘stress’ of sodium pentobarbital anesthesia and cannulation of the femoral artery, and adrenal venous levels of 17-OHCS were very low in hypophysectomized dogs subjected to the ‘stress’ of laparotomy. Between the 15th and 30th day following hypophysectomy a normal removal of intravenously administered cortisol was found. However, at this time after hypophysectomy an inferior response in plasma 17-OHCS was demonstrated following the intravenous administration of ACTH. The oral administration of adrenal hormones to normal dogs for 15 days led to a similar impairment in the responsiveness of adrenocortical tissue to ACTH injection. It has thus been shown that lack of pituitary function for 15–30 days will rapidly result in a functional atrophy of the canine adrenal cortex. The data further demonstrate that intravenously administered cortisol is removed or ‘utilized’ at a normal rate in animals lacking pituitary function. Small remnants of anterior pituitary tissue appear to maintain a reduced but measurable adrenocortical capacity in the dog.
Distribution of Glycogen in the Rat Heart
Authors: Weisberg Jerry , Rodbard Simon
Published: December 2017

The total and trichloroacetic acid soluble fractions of glycogen were determined in various portions of the rat heart. The amount in each portion was compared on the basis of the nitrogen content of the same sample. The total glycogen concentration was highest in the atria, lowest in the left ventricle and intermediate in the septum and right ventricle. A similar distribution was found for TCA soluble glycogen. The possible role of glycogen in cardiac energetics and structure is discussed.
Core to Surface Thermal Gradients in the Rat at Several Environmental Temperatures
Authors: Bartlett R. G. , Mantel N. , Foster G. L. , Bernstein P.
Published: December 2017

Clipped (restrained and nonrestrained) and nonclipped (restrained and nonrestrained) adult male rats were exposed to varying cold environments. Colonic, subcutaneous and cutaneous temperatures were measured. Restraint produced hypothermia at low temperatures (0 and 8°C) and at higher temperatures (16 and 28°C) it resulted in the virtual disappearance of the normal subcutaneous to skin surface temperature gradient. It was also observed that when the severity of stress was increased (e.g. by lowering the temperature of the cold room or adding clipping to the cold stress) the thermolability among the individuals of a group of restrained animals not only increased but also appeared to be more uniform. Thus with mild stress (e.g. clipping with severe cold or restraint with mild cold) only some of the animals showed thermolability but with a more severe stress all animals became hypothermic.
Coagulation Mechanism and Effect of Heparin in Hemorrhagic Shock
Authors: Smith James J. , Grace Robert A. , Hussey Clara V.
Published: December 2017

Hemorrhagic shock was produced in anesthetized and unanesthetized dogs by bleeding to fixed arterial pressure levels for specified periods using Wiggers' method. Blood was drawn through an ion exchange resin and at the end of the hypotension was reinfused simultaneously with the removed ions. Early in the hypotension there was usually some shortening of blood coagulation time. In the late hypotension and reinfusion period 75% of the dogs had a distinct prolongation of clotting time. Prothrombin activity and blood platelets showed a marked progressive decline during the shock period. Special tests indicated that the coagulation defect was mainly due to a decrease of labile factor in conjunction with a second deficiency, most likely prothrombin. There was no discernible deficiency of stable factor nor any release of heparinoids during the shock procedure. It is suggested that the hepatic anoxia and the resultant diminished production of labile factor and prothrombin contributes importantly to the clotting defect. Prior administration of heparin (10 mg/ kg) tended to lower mortality and increase survival time but did not afford critical protection against the development of irreversibility.
Mesenteric Hemodynamics During Hemorrhagic Shock in the Dog With Functional Absence of the Liver
Authors: Selkurt Ewald E.
Published: December 2017

The sequence of hemorrhagic shock was studied in dogs with functional absence of the liver produced by ligation of vascular inflow circuits. Establishment of a portal to jugular shunt permitted continual measurement of intestinal blood flow. It was found that this vascular bed exhibited the characteristic hyperemic response previously observed in dogs with intact livers, studied under similar conditions. Other hemodynamic changes symptomatic of irreversibility were observed. It is concluded that the liver made anoxic during shock does not contribute to irreversibility, and that it is more likely that it exerts a protective role. An hypothesis is advocated that hypotension creates conditions in the intestinal bed which favor production or release of vasodepressor agents or material toxic to the cardiovascular system. In the absence, or impairment of the normal protective role of the liver, these gain access into the general circulation with deleterious consequences to circulatory homeostasis.
Iron Metabolism in the Pregnant Rabbit
Authors: Bothwell Thomas H. , Pribilla Walther F. , Mebust Winston , Finch Clement A.
Published: December 2017

Studies on iron metabolism were made in pregnant rabbits. The amount of iron transported from the maternal plasma to fetus increased progressively with age and weight of the fetus. By the end of the pregnancy 90% of the plasma iron turnover was directed to the fetus. The majority of fetal iron is deposited as nonhemoglobin iron. Placental iron transport occurs against a concentration gradient. The uptake of iron by the placenta is an active process independent of the fetus, and retrograde transfer of iron from the fetus to mother does not occur. Studies of altered maternal metabolism indicate that placental transport reflects both fetal demands and state of iron metabolism in the mother.
Depletion and Reaccumulation of Mitochondrial Sodium and Potassium: Effect of Adrenalectomy
Authors: Share Leonard
Published: December 2017

The effect of 6–7 days of adrenocortical insufficiency (tap water and no steroids) on the movements of sodium and potassium in rat liver and kidney mitochondria was studied. Rat liver and kidney mitochondria were depleted of sodium or potassium. The ability of these particulates to accumulate sodium or potassium upon the addition of the particular ion to the incubation medium was determined. Adrenalectomy was without effect on the following: the rate of depletion of or the ability to reaccumulate sodium or potassium, the mitochondrial water content or the intramitochondrial potassium concentration. However, adrenalectomy did result in a consistently higher sodium concentration in kidney mitochondria in the sodium depletion-reaccumulation experiments.
Heat Production and Heat Loss in the Dog at 8–36°C Environmental Temperature
Authors: Hammel H. T. , Wyndham C. H. , Hardy J. D.
Published: December 2017

Metabolic and thermal responses of three dogs were made in a rapid responding calorimeter at temperatures ranging from 8°C to 36°C. These dogs were acclimatized to a kennel temperature of 27°C and had critical temperatures between 23°C and 25°C. The only physiological responses to low environmental temperatures were a moderate decrease in total heat content and an increase in heat production. The tissue conductance and the cooling constant of the fur did not effectively decrease below the levels obtaining throughout the neutral zone. In a hot environment heat loss from the respiratory tract was greatly increased. Although there was a great increase in the tissue conductance in the hot environment, conductance of heat through the tissue became decreasingly important as the air temperature approached body temperature so that panting became increasingly important for maintaining thermal balance. It is concluded that the vasomotor response of the peripheral vascular system is primarily a mechanism for dissipating excess heat produced during exercise; it is practically unimportant as a heat conserving mechanism. Effective changes in the total insulation of the fur can only be achieved by changing the surface area of the body, particularly those areas which are thinly furred, and not by any important change in the fur thickness through pilomotor activity.
Proteolytic Activity of Human, Rabbit and Bull Semen With Special Reference to Peptidases in the Genital Tract of Male Rabbit
Authors: Thorsteinsson Thorsteinn
Published: December 2017

The semen of bull, rabbit and man hydrolyses various synthetic peptides but only human semen is active on casein. An investigation of the peptidase activity of extracts from the testes, epididymis, epididymal sperm and the accessory glands of the rabbit has revealed a strong peptidase activity. Seminal plasma of vasectomized rabbits shows diminished peptidase activity as compared to normal seminal plasma. Grinding of the human or rabbit semen has no effect on the peptidase activity but grinding of bull semen increases this activity. Human semen has the highest activity with respect to all but one of the seven peptides tested. Human semen at first forms a gel which later dissolves but the gel formed from semen of rabbit does not. Bull semen does not form a gel. The stronger peptidase activity of the human semen may indicate that these enzymes play an important role in the complete breakdown of the gel forming proteins, whereas the occurrence of these enzymes in close connection to the spermatozoa in the other species suggests some role of peptidases for the metabolism of the spermatozoa or for fertilization.
Effect of Acute Ethanol Intoxication on Liver and Plasma Lipid Fractions of the Rat
Authors: Di Luzio N. R.
Published: December 2017

Plasma and liver lipid fractions of rats were studied 8 and 16 hours after administration of a single oral intoxicating dose of ethanol. When compared to rats which received an isocaloric amount of glucose, no differences were noted in plasma phosphatide, cholesterol or triglyceride concentrations. Liver weight and triglyceride concentrations were significantly elevated 8 and 16 hours after ethanol administration. The increase in liver neutral fat was not prevented by the simultaneous administration of choline and was not associated with alterations in liver or plasma phospholipid metabolism. The possible mechanisms of the development of a fatty liver following acute ethanol intoxication are discussed with particular reference to its possible hepatotoxic action.
Effect of Oxygen Deprivation on the Metabolism of Fetal and Adult Tissues
Authors: Villee Claude A. , Hagerman Dwain D.
Published: December 2017

Fetal liver slices have a remarkably high rate of lipogenesis anaerobically as well as aerobically, shown by the incorporation of carbon-14 from pyruvate into lipids. In contrast, slices of adult or 1-day-old liver have a much lower lipogenetic rate anaerobically than aerobically. Fractionation of the fetal liver lipids showed that phospholipid and glyceride fatty acids are synthesized at essentially equal rates aerobically and anaerobically but cholesterol synthesis is much slower in nitrogen than in oxygen. Fetal liver slices have a respiratory quotient of about 1.5, further evidence of rapid lipogenesis. Lactate production by fetal liver is 90% greater in nitrogen than in oxygen; that of adult liver is only 30% greater. Fetal liver metabolizes anaerobically much more pyruvate carbonyl carbon to carbon dioxide than adult liver does. Direct evidence from the rate of conversion of labeled glucose to labeled pyruvate showed that the glycolytic enzymes of fetal liver respond to anaerobiosis more effectively than those of adult liver. Thus the aging of fetal tissue to adult includes a loss of a) the high rate of glycogen deposition, b) the high rate of activity of one or more glycolytic enzymes which are rate-limiting in the adult, and c) the high rate of lipogenesis which is evident anaerobically as well as aerobically.
Chromatic Responses of Fundulus to Lysergic Acid
Authors: Wilber Charles G.
Published: December 2017

Lysergic acid diethylamide (LSD) was administered to Fundulus heteroclitus by injection and by immersion. In all experiments light-adapted fish became darker: the concentrated melanophores were dispersed. The degree of dispersal was directly related to the dose by a nearly straight line. A few behavioral changes in the fish were observed. If immersed in suitable concentrations of the drug in sea water, Fundulus absorbed a sufficient amount, probably through the respiratory surfaces of the gills, to disperse the melanophores. To darken immersed fish, a 1-hour Ct (concentration x time) of 120,000 mg min/m3 is required. Apparently the drug exerts a depressant action on specific loci in the brain from which the melanophore-concentrating fibers originate; this action allows the melanophore-dispersing fibers to darken the fish.
Reciprocal Blood Exchange in Parabiosed Albino Rats
Authors: Kamrin Benjamin B.
Published: December 2017

Serial electrophoretic studies on single rats, sham-operated single rats, treated and untreated successful parabiosed pairs of rats demonstrated that the albumin/globulin (A/G) ratio reflects the state and condition of the animals. The individually characteristic electrophoretic patterns and A/G ratios of single animals exhibit close similarity when single animals are surgically united and attain the successful parabiotic state. After a brief period of similarity, the individual electrophoretic patterns and A/G ratios reassert themselves; the animals meanwhile continue in successful union. Continued serial examination of the serum of successfully parabiotic pairs disclosed that an apparent exchange of A/G ratios occurred between the parabionts. This finding suggests that intermittent uneven reciprocal exchange has occurred. Other significant changes in the levels of the various serum components are described.
Gastrointestinal Changes in the Rat on Realimentation
Authors: Ivy A. C.
Published: December 2017

Forty-eight male rats were divided into equal groups by pairing as regards body weight. One group of 24 were injected subcutaneously 14 hours after the withdrawal of food with C14-l-histidine; the second group was not injected. Twelve rats in each group were fasted for 72 hours and twelve others were fasted for 48 hours and then fed for 24 hours. At 72 hours the wet and dry weight of the entire glandular stomach and small intestine was determined separately, and the C14-histamine in each of those which had received C14-l-histidine was determined. Realimentation for 24 hours increased the wet and dry weight of the stomach by 15% and 13%, respectively, and of the intestine by 58% and 40%, respectively. Therefore, after 48 hours of fasting realimentation for 24 hours affects the composition of the intestine more than the stomach. Twenty-four hours of realimentation reduced the C14-histamine content of the stomach by 58% and of the intestine by 30%. It was found by calculation that a maximum of only 10% of the C14-histamine lost from the stomach and 30% from the intestine could be accounted for by desquamation of superficial cells. The rate of loss and renewal of superficial cells in the intestine during 24 hours of realimentation after 48 hours of fasting was approximately three times faster than that in the stomach.
Spreading Depression of Activity in Amphibian Retina
Authors: Gouras Peter
Published: December 2017

Microelectrode studies on excised amphibian retina have uncovered a phenomenon of spreading retinal depression which in many respects resembles Leão's spreading cortical depression. The phenomenon is characterized by a spontaneous ‘milky’ wave that periodically marches across the surface of the retina and lasts for 2–3 minutes at any one point. There is a concomitant and sudden negative shift in the resting retinal potential of 1–2 mv which gradually returns to its previous level in 3–6 minutes. As the wave front approaches a microelectrode recording ganglion cell activity, there is a marked increase in its spontaneous firing climaxing in an intense discharge as the wave engulfs the electrode. A profound depression follows so that even the most intense photic stimulation becomes unable to elicit a local response. As the color change disappears and the d.c. level returns, the local area of retina becomes reexcitable. Similar changes occur in the local electroretinogram, which always returns slightly before the ganglion cell activity. The process occurs spontaneously but can also be induced by trauma, electrical current, or the application of KCl. It happens less often in bright light or with oxygenation, although neither of these factors can prevent its occurrence. It appears to be entirely reversible.
Effect of Exercise on Number of Myofibrils per Fiber in Sartorius Muscle of the Rat
Authors: Holmes Richard , Rasch Philip J.
Published: December 2017

The number of myofibrils per fiber at seven different cross-sectional levels of the sartorius muscles of exercised rats was compared with the number of myofibrils per fiber of the sartorius muscles of unexercised control animals. No statistically significant differences were observed. The number of myofibrils per fiber in the exercised animals was more variable than in the control animals, and the pattern of distribution suggested increases in the number of myofibrils per fiber at the ends of the muscles.
Action of Serotonin on Conversion of Fibrinogen to Fibrin
Authors: Kátó L. , Gözsy B.
Published: December 2017

Serotonin interferes in vitro with the conversion of fibrinogen to fibrin in the presence of thrombin as evidenced by changes in clot opacity and clotting time. Clot opacity measurements on such systems show that the presence of moderate amounts of this reagent permits the formation of polymers, which exhibit low opacity at the time of clotting and are characterized as ‘fine clot.’ The prolongation of clotting time by this reagent produces gels of high rigidity and a slight tendency to syneresis. Evidence is presented that serotonin acts upon fibrinogen rather than on thrombin and the effects are reversible. The effects are assumed to be the results of interference with van der Waals' forces.
Summating Potentials of the Cochlea
Authors: Davis Hallowell , Deatherage Bruce H. , Eldredge Donald H. , Smith Catherine A.
Published: December 2017

When the ear is stimulated by a steady tone scala media and scala vestibuli become less positive electrically relative to scala tympani. This ‘summating potential’ (SP) is a d.c. change related to the root-mean-square of the acoustic pressure, integrated over one or two waves. It increases up to injurious sound pressure levels. It is increased by additional positive polarization of scala vestibuli or media. It is modified and may even be reversed in sign by hydrostatic displacement of the cochlear partition. It broadly resembles the cochlear microphonic (CM) but is more resistant to most drugs and anoxia. The negative SP depends on the integrity of the internal hair cells. The external hair cells produce CM and may also generate small SPs, usually positive in sign. The SP generated by 7000 cps tone bursts is strong in the basal turn while those by 2000 and 500 cps are very small here but are strong in the second and third turns, respectively. The theory is proposed that the negative SP is the response of the internal hair cells, an amplifier action intermediate between a mechanical detector action of the cochlear partition and the excitation of nerve impulses. Both CM and SP depend on bending of the ‘hairs’ of the sensory cells in the proper direction.
Glycogen Metabolism in the Isolated Liver
Authors: Sokal Joseph E. , Miller Leon L. , Sarcione Edward J.
Published: December 2017

Glycogen metabolism was studied in isolated rat liver, using the perfusion apparatus developed by Miller ( J. Exper. Med. 94: 431, 1951). It proved possible to maintain stable glycogen levels for as long as 3 hours in this system, at glucose concentrations of 200–300 mg% in the perfusing blood. Glycogen synthesis was observed in isolated livers obtained from fasted animals, at glucose concentrations entirely within the physiological range. At high glucose concentrations, glycogen levels reached 2% or more. Glycogen synthesis was observed both with and without insulin, but it took place at lower glucose concentrations when insulin was added. Infusion of epinephrine induced glycogenolysis in the isolated liver. Norepinephrine was less active as a glycogenolytic agent.
Nature of Proteinuria Induced by Uranium in Rats
Authors: Magee Marguerite , Foreman Harry
Published: December 2017

Following administration of uranium parenterally into rats in an acute dose, the increase in protein excretion consisted not only of an increase in the normally occurring albumin but to a greater extent an increase in the various globulins. At the height of proteinuria, the electrophoretic pattern of the excreted proteins strongly resembled the pattern of the serum proteins. The appearance of these serum-like urinary proteins suggests a defect in the glomerulus filtration apparatus and provides further evidence that the glomerulus, as well as the tubule, is altered by uranium administration.
Oxygen Dissociation Curves of Mammalian Blood in Relation To Body Size
Authors: Schmidt-Neilsen Knut , Larimer James L.
Published: December 2017

Oxygen dissociation curves were determined in mammalian blood at the CO2 tension of the organism, without the addition of buffers, dilution of the blood, or other alterations. It appears that the dissociation curve is related to body size in such a way that the blood of smaller animals has a higher unloading tension for oxygen. This finding is discussed in relation to the higher metabolic need for oxygen of the smaller animal. It is suggested that, in addition to the higher capillary density in the small animal, a higher unloading tension for oxygen also contributes to the steepness of the diffusion gradient for oxygen from the capillary to the tissue cells.
Potassium Transfer Kinetics in the Isolated Dog Heart. Influence of Contraction Rate, Ventricular Fibrillation, High Serum Potassium and Acetylcholine
Authors: Wood John C. , Conn Hadley L.
Published: December 2017

Potassium transfer kinetics were studied in the perfused isolated dog heart with the aid of radioactive tracer (K42) techniques. The effects of heart rate, ventricular fibrillation, high serum potassium and acetylcholine on cell-interstitial fluid potassium exchange were investigated. A positive linear correlation between potassium exchange and heart rate was found. Potassium transfer per beat was less than that found previously in the in vivo dog heart. A relative increase in potassium flux was noted when the heart was arrested by high serum potassium or slowed by acetylcholine. A relative decrease in calculated potassium flux accompanied ventricular fibrillation. The results suggest that potassium exchange between the myocardial cell and interstitial fluid is a function of heart rate, and that extracellular potassium concentration, acetylcholine and possibly the strength of myofibril contraction are other factors influencing exchange. The decreased exchange in ventricular fibrillation may reflect incomplete cell membrane depolarization.
Mixing of Labeled Erythrocytes in the Dog's Spleen
Authors: Kraintz L. , de Boer J. , Smith E. L. , Huggins R. A.
Published: December 2017

Dogs anesthetized with morphine-pentobarbital were injected with Cr51-tagged red cells, and their mixing time in the general circulation and the spleen was compared. The necessary blood samples were taken and the spleens rapidly excised at 10, 20 or 30 minutes after the injection of the tagged red cells. When the data were grouped according to the size of the spleen and irrespective of the time of removal, the mixing of tagged red cells in small spleens was practically the same as in the general circulation. With increasing sizes of spleens the mixing appeared to be progressively less complete than in the general circulation. If the spleen size was disregarded and the data grouped according to the time after the injections of tagged red cells mixing in the spleen was still incomplete after 30 minutes. However, the maximum mean possible error that could be introduced into the determination of total red cell volume if all the unmixed red cells were ejected into the general circulation would be less than 5% at the 20-minute period.
Effect of Bile Acids and Other Factors on Cholesterol Uptake by Inverted Intestinal Sacs
Authors: Smith Archie L. , Treadwell C. R.
Published: December 2017

Conditions for the use of inverted sacs of rat small intestine for quantitative studies of cholesterol uptake are described. The uptake of cholesterol by sacs did not require glucose in the incubation medium. Albumin aided cholesterol uptake but was not obligatory for this process. A binding of cholesterol to a cellular protein is proposed as the mechanism for the entrance of cholesterol into intestinal mucosal cells. Both conjugated and unconjugated bile acids inhibited cholesterol uptake possibly by blocking the binding sites of the protein responsible for cholesterol uptake. Commercial taurocholate and glycocholate contain an inhibitor of cholesterol uptake other than the bile acid.
Localized Responses in Auditory Cortex to Brief Tones in High Level Noise
Authors: Tunturi Archie R.
Published: December 2017

By observing the evoked potentials at 50 electrodes on the MES auditory cortex, essentially the same foci of response for P pulses of different frequencies were found in the presence of high level thermal noise as at the absolute threshold. The wide band thermal noise produced a linear threshold shift for the P pulse response foci. The best representation of frequency was obtained for signal to noise ratios of 0 to 20 db. The masking effect or threshold shift was primarily confined to the ear in which the P pulse was delivered. Under these conditions, it is expected that the information storage capacity of the MES area for spectra would remain essentially the same for a 20-db signal to noise ratio at any level of thermal noise. Also, because of the absence of contralateral masking, the representation for both ears could be maintained at an optimum in spite of high level noise in one ear.
Transport of radioiodide between thyroid gland and blood in mice and rats
Authors: Wollman Seymour H. , Reed Franklin E.
Published: December 2017

Equilibration data were obtained for thyroids of various activities in rats and mice given a single dose of propylthiouracil to block organic binding of radioiodine. Data were compared with an open two-compartment model of the thyroid characterized by a one-way thyroid clearance of serum radioiodide and an exit rate constant for the transport of radioiodide from the thyroid to the blood. The model generally fitted the data within experimental error. Clearances increased with thyroid activity. Exit rate constants were much larger for animals fed thiouracil than for other animals. Thiocyanate increased the exit rate constant but did not change the thyroid clearance of serum radioiodide significantly. A new open three-compartment thyroid model was introduced and was used to explain how thiocyanate could increase the exit rate constant by inhibiting the transport of iodide from the follicular cells to the lumen of the follicle.
Extrarenal action of the adrenal cortex on electrolyte metabolism in nephrectomized and nephrectomized-eviscerated rats
Authors: Tompkins Mary Jane , Eckman Edward , Share Leonard
Published: December 2017

A study was made of the extrarenal action of the adrenal cortex on sodium and potassium metabolism in the rat. There was a reduction in the plasma potassium concentration 24 hours after the administration of desoxycorticosterone, 2 mg/rat, in the adrenalectomized-nephrectomized rat. Treatment with hydrocortisone, 5 mg rat, resulted in the opposite effect. Corticosterone and 2-methyl-9α-fluorohydrocortisone were without effect. In another series of experiments, adrenalectomy resulted in an elevation in the plasma potassium concentration in nephrectomized-eviscerated rats. This change could be detected as early as two hours after operation. The intravenous administration of large doses of desoxycorticosterone, hydrocortisone, corticosterone and aldosterone were without effect. It is suggested that there is a movement of potassium into the extracellular fluid in the absence of the secretions of the adrenal gland.
Thermoregulatory, brain and behavioral mechanisms during entrance into hibernation in the squirrel, Citellus beecheyi
Authors: Strumwasser Felix
Published: December 2017

In the continuous record of brain temperature during single entrances into hibernation there are gently falling temperature steps and longer maintained plateaus. Without these plateaus, brain temperature would decline roughly 18°C/hr. The normal rate of decline is 2–4°C/hr. with considerable slowing as the critical point is approached. The plateaus are initiated and maintained by periodic shivering. The ‘steps’ are ascribed to a vasodilation in the dorsal skin and a relative reduction in muscle tone. Each of the consecutive temperature curves of entering hibernation shows a faster rate of decline of temperature. During entrance, the heart rate declines 50%, with as small a change in temperature as 0.6°C occurring entirely around 33–34°C. Evidence is presented for a shift of balance toward the parasympathetic system during entrance into hibernation. As temperatures decline, the squirrel is capable of ‘spontaneous’ complex behavior. Neuronal activity changes correlatable with events during entrance into hibernation consisted of a 10 cps motor cortex discharge preceding and continuing during shivering and an amygdaloid-hippocampal 5 cps rhythm occurring after shivering at a time when the motor cortex discharge started to disintegrate. The correlates mentioned are absent during arousal shivering, indicating that a different controlling system was active here.
Serum electrolyte and hematocrit changes in young rabbits following hemorrhage
Authors: Critz Jerry B. , Merrick Arthur W.
Published: December 2017

Normal serum sodium, potassium, magnesium and the hematocrit were determined in 1-day-, 5-day- and 2-month-old white New Zealand rabbits. A significant increase in sodium and magnesium was observed in the 2-month-old rabbits; the potassium level was the same in all three groups. The hematocrit in the 1-day-old series was significantly higher than that observed in the older groups. Serum sodium, potassium, magnesium and the hematocrit also were determined in 2-month-old rabbits subjected to a 10, 20 and 30% hemorrhage. Analyses were made 8, 24, 48, 96 hours and 1 and 2 weeks subsequent to hemorrhage. Moderate to severe hemorrhage in these young rabbits produced a decrease in sodium and an increase in potassium which, in adult animals, is reportedly due to hemodilution by intracellular fluid. A 10% blood loss had no effect upon serum magnesium whereas a more severe hemorrhage resulted in a significant magnesium decrease. Several theories are suggested for this magnesium loss, which apparently has not been observed in adult animals. The decrease in hematocrit may be related to the severity of hemorrhage and it is suggested that no red cell reserve exists in young rabbits.
Quantitative participation of fatty acid and glucose substrates in oxidative metabolism of excised rat diaphragm
Authors: Neptune E. M. , Sudduth H. C. , Fash F. J. , Foreman D. R.
Published: December 2017

The conversion of 1-C14-octanoate, 1-C14-butyrate and glucose-U-C14 to C14O2 by rat diaphragm was studied. From the data obtained, the conclusion is that added fatty acid substrates participate extensively in rat diaphragm metabolism in vitro. Added glucose participates to a lesser extent, but the possibility of intracellular dilution does not permit exact quantitative measurement. Additional evidence is presented which indicates that the ketone body ß-hydroxybutyrate is utilized by rat diaphragm muscle, but to an undetermined extent.
Effect of acetazoleamide on thyroid metabolism
Authors: Krieger D. T. , Moses A. , Ziffer H. , Gabrilove J. L. , Soffer L. J.
Published: December 2017

Previous studies showed Diamox (acetazoleamide) to be an effective depressant of thyroidal radioactive iodine uptake. It was hypothesized that this effect was mediated via carbonic anhydrase inhibition. The presence of carbonic anhydrase was demonstrated in rat and human thyroid tissue. Diamox and other sulfonamide like drugs were tested for their relative carbonic anhydrase inhibitory potency and depressant effect on in vitro radioactive iodine uptake. No correlation between these two effects could be observed, and carbonic anhydrase addition did not reverse the inhibitory effect of Diamox. These experiments therefore fail to provide an explanation of the mechanism of depression of thyroidal radioactive iodine uptake by Diamox.
Morphological classifications of vertebrate blood capillaries
Authors: Bennett H. Stanley , Luft John H. , Hampton James C.
Published: December 2017

Morphological features of blood capillaries from various vertebrate forms and organs are presented. Simple classifications are proposed, based on presence or absence of continuous basement membrane, on the nature of the endothelial cell and on the presence or absence of a complete investment of pericapillary cells. It is suggested that these varying capillary structural features may be relevant to problems relating to exchange of materials between blood plasma and parenchymal cells. Simple three-digit notation systems are presented for characterizing and designating the type of any capillary with respect to the classifications submitted.
Analysis of the common carotid occlusion pressor reflex in the anesthetized dog
Authors: Hardman Harold F. , Baird Walter M. , Suits Daniel B. , Lum Bert K. B.
Published: December 2017

The relationship between mean arterial blood pressure and the common carotid occlusion pressor response in dogs was found to be linear over a blood pressure range of approximately 100–160 mm Hg. These results were obtained when blood pressure was reduced by spontaneous decay, hemorrhage or the administration of a vasodilator drug, sodium nitroprusside. It was found that the slope of the regression line varied considerably for individual dogs and could not be predicted in advance of actual experimentation. A single regression line drawn from pooled data for this reflex has no predictive value in determining the regression line slope for an individual dog because of the extensive variation in slope values among dogs. In order to predict the carotid occlusion pressor response at a given mean arterial pressure for a given dog one must know the slope of the regression line for the reflex in that dog.
Effect of denervation and cocainization on activity of creatine synthesizing enzyme and phosphorylase in skeletal muscle
Authors: Matsui Takashi , Kuriaki Kaname
Published: December 2017

Creatine synthesizing enzyme and phosphorylase were determined in the gastrocnemius of the rat, and effects of epinephrine, norepinephrine, cocaine and denervation on them were studied. Denervation caused decrease of activity of the creatine synthesizing enzyme and increase of phosphorylase activity. Cocaine (1 x 10–4 and 3 x 10–4) exerted denervation-like action on both enzyme systems. Epinephrine (2 x 10–5) increased the activity of creatine synthesizing enzyme in the normal muscle, but it did not affect the enzyme activity of the denervated muscle. Conversely, norepinephrine (2 x 10–5) increased the enzyme activity of the denervated muscle but it did not affect that of the normal muscle significantly. Epinephrine (20 µg i.p.) and norepinephrine (100 µg i.p.) increased the phosphorylase activity ratio, and the former was more potent than the latter. Neither drug affected the enzyme in the denervated muscle.
Metabolism of rat brain mitochondria during postnatal development
Authors: Dahl Dennis R. , Samson Frederick E.
Published: December 2017

Mitochondria from whole brains of female Sprague-Dawley rats 1–50 days old were examined for relative cellular quantity and oxidative-phosphorylative capacity. The concentration of mitochondrial protein (MP) is constant during the first 5 days after birth, i.e. the rate of synthesis of MP is the same as the rate of total brain growth. This is followed by a period of accelerated MP synthesis during which the MP, initially at 17%, increases to about 26% of total cerebral protein. By the 21st day (weaning), the rapid proliferation of MP tapers off. Calculation of the relative amount of MP per cell (assume a constant amount of desoxyribose nucleic acid in each cell) reveals an increase per cell throughout the entire age range studied, with a three-fold increase during the first 21 days. The rate of O2 utilization per milligram MP is constant throughout the age range studied; the rate of high-energy phosphate synthesis per milligram MP declines slightly. Apparently, newly formed mitochondria are fully capable of oxidative-phosphorylation. Also, the well known acceleration of O2 utilization with brain development can be accounted for by the increase in MP. The relative gain in MP per cell during development may be a prerequisite to the greater power cost of maintaining a larger surface area as the growing cells extend into the extracellular space.
Fat metabolism in experimental obesities. IX. Lipogenesis and cholesterogenesis in yellow obese mice
Authors: Zomzely Claire , Mayer Jean
Published: December 2017

Yellow mice fed ad libitum exhibit a greater rate of lipogenesis and cholesterogenesis than their controls. Females show a fatty acid content in the liver and in extrahepatic tissues which is twice as high as the males. Unlike the males, they are hypercholesterolemic and also show an elevated rate of lipogenesis after an 18-hour fast.
Mechanical response of the frog's rectus to potassium. Effect of various substances
Authors: Lorković Hrvoje
Published: December 2017

Veratrine and sodium fluoride potentiate the twitch fiber reaction, as revealed by the changes in the first phase of the frog's rectus potassium contracture. Caffeine potentiates the reaction of both twitch and slow fibers. Sodium thiocyanate and chloroform mainly potentiate the reaction of slow fibers. Glucose, ethyl ether and acetophenone depress the twitch fiber reaction, potentiating, to various degrees, the slow phase. Only in a few cases is the reaction pattern of the muscle affected by changes in exposure time and concentration of these agents. The different actions of the ‘sensitizers to potassium’ are discussed in the light of the present investigations.
Mechanical response of the frog's rectus to potassium. Two phases of the KCl contracture
Authors: Lorkovic Hrvoje
Published: December 2017

The mechanical response of rectus abdominis muscles of Rana esculenta to potassium ions (5.6–23.5 mm in Ringer's solution) shows two distinct phases. The twitch fiber reaction, giving rise to the first phase of the response curve, does not last more than 1–2 minutes. It can be provoked with KCl concentrations of the order of 5–7 mm; its intensity is not much influenced by increasing KCl concentrations higher than 10 mm; its intensity is reduced by high CaCl2 concentrations, and also by shortening the length of the interval between two exposures of the muscle to increased KCl concentrations. The slow fiber reaction, giving rise to the second phase, is a true tonic contracture which can be obtained only with concentrations of KCl larger than 10 mm. Changes in the CaCl2 concentration and in the length of the interval do not affect it so much as the first phase.
Temperature and vagal effects
Authors: Young Wei
Published: December 2017

Vagal effects were observed in isolated vagal heart preparations of Rana pipiens over periods as long as 72 hours. The normal effect was partially blocked by lowering the temperature to about 14°C, and there was a complete block at 10°C and below. On rewarming the preparation the vagal effects recurred; and this process could be repeated cyclically several times. The upper temperature limit of vagal effects seemed to be at 31°C above which the heart stopped. At 32°C however, the stopped heart was still susceptible to stimulation and it could be made to beat for a short time. Tetraethyl pyrophosphate lowered the critical temperature limit by about 3°. The activation energy of vagal effect was calculated in the neighborhood of 46,000 calories, which was similar to value of most enzymic function. It is therefore suggested that the observed phenomenon results primarily from the effect of temperature on choline esterase and acetylase systems.
Synthesis and secretion of pepsinogen in the rat; effects of alteration of adrenal activity and of body hydration
Authors: Hirschowitz Basil I. , Underhill William G.
Published: December 2017

Simultaneous measurements of peptic activity were made in the stomach wall and in gastric secretions collected after 2 hours of pylorus ligation. These measurements allowed interpretation of alterations of pepsin secretion in terms of residual stored pepsinogen. Two mechanisms were differentiated as having an influence on pepsinogen secretion: a ‘release mechanism,’ whereby pepsinogen was retained in the cell and a ‘synthesis mechanism,’ whereby inadequate synthesis of enzyme resulted in depression of pepsinogen secretion. Thus the injection of 5% dextrose, in this case acting as a hypotonic solution caused inhibition of the release mechanism, similar to that seen with atropine, whereas adrenalectomy reduced the synthesis of pepsinogen which resulted in a diminished output of enzyme, without affecting the release mechanism. Isotonic saline injections stimulated the secretion of, and as a result increased the synthesis of pepsinogen. Adrenalectomy reduced gastric secretion of acid as well as pepsinogen; effects that were grossly exaggerated by salt withdrawal, which also resulted in an excessive secretion of sodium into the stomach. ACTH given for 1–3 weeks, by contrast with the adrenal insufficiency state, did not stimulate gastric secretion, emphasizing again the trophic or permissive rather than stimulant role of the adrenal cortex in gastric secretory mechanisms.
Mechanism of gastric hypersecretion following portacaval transposition
Authors: Kohatsu Soichi , Gwaltney James A. , Nagano Kazuo , Dragstedt Lester R.
Published: December 2017

Dogs were prepared with vagus denervated total stomach pouches and with isolated vagus denervated Heidenhain and antrum pouches. Under these conditions the nervous phase of gastric secretion is excluded, and since the antrum does not come in contact with food, its activity in the release of gastrin is minimal. Nevertheless, portacaval transposition produced a marked augmentation of gastric secretion, presumably because some gastric secretory hormone or secretagogue elaborated by the intestines escapes inactivation or excretion by the liver.