bluuebunny/crossref_metadata_2025 huggingface dataset:
Water and electrolyte composition of the bovine uterus in pregnancy
Authors: Bitman Joel , Hawk H. W. , Cecil Helene C. , Sykes J. F.
Published: December 2017

Determinations of water, its extracellular-intracellular distribution and electrolytes were made in the uterus and placenta of the cow during pregnancy and parturition. The endometrium and fetal cotyledons showed a decrease in water content during the first half of pregnancy and relative constancy thereafter until term. Maternal cotyledons showed a steady decrease throughout gestation. The myometrial water content was slightly higher during the middle of pregnancy. Na and Cl values generally decreased during the first half of pregnancy. K content increased during gestation. Uterine water distribution during pregnancy was very similar to that observed during progesterone domination of the uterus, with 40–50% of the water in the extracellular phase. At parturition there was a sharp reversal to the distribution seen under estrogen influence, 60–70% being extracellular. The changes in water and electrolyte composition of the uterus during pregnancy are due mainly to the growth of the uterus and its contents and to the influence of hormonal factors.
Species differences in effect of gram-negative endotoxin on circulation
Authors: Kuida Hiroshi , Gilbert Robert P. , Hinshaw Lerner B. , Brunson Joel G. , Visscher Maurice B.
Published: December 2017

Studies were made in 5 monkeys, 7 rabbits, and 33 cats of the effect of gram-negative endotoxin on aortic, pulmonary artery (PAP), and portal venous (PVP) pressures; and on changes in weight of a short segment of intestine. Studies of blood pooling were also made in 12 cats. The responses in these species were compared with those previously observed in the dog. Although variable degrees of hypotension developed at one time or another in all animals following injection of endotoxin, the early precipitous hypotension that characteristically occurs in the dog was observed only in the cat. However, in this species the dramatic fall in pressure could be ascribed to pulmonary vascular constriction and acute right ventricular hypertension and failure, and not to splanchnic pooling. PAP also became elevated in the monkey and the rabbit, but usually was of lesser magnitude and did not appear to explain the development of the relatively late hypotension that occurred in these species. The absence of significant increases in gut weight and the minor increments in PVP in all animals indicate that in none of these species is hepatic vein constriction and splanchnic pooling a significant mechanism in producing early shock as it is in the dog. Pathologic gross and microscopic studies in the monkey and gross examinations in the other species supported this conclusion.
Potentials evoked by sound in the auditory cortex of the cat
Authors: Gumnit Robert J. , Grossman Robert G.
Published: December 2017

The electrical responses of the auditory cortex of awake, loosely restrained cats were examined with chronically implanted calomel electrodes and d-c recording systems. Stimulation with a single click evoked a complex triphasic response in which a large surface positive potential (duration, 250 msec) followed the classic diphasic response. This second positive wave was absent in natural sleep and under light barbiturate anesthesia. A similar late positive wave of long duration, evoked by a flash of light, was found in the visual cortex. A rapid series of clicks evoked a surface negative shift which was maintained for the duration of the stimulus. A tone or white noise presented for several seconds evoked a negative shift of the same general form. A pure tone of moderate intensity presented simultaneously with a click greatly enhanced the click-evoked response. White noise of moderate intensity presented simultaneously with a click diminished the size of the click-evoked response.
Neuromyal blocking action of mescaline
Authors: Schopp Robert T. , Kreutter William F. , Guzak Steven V.
Published: December 2017

The close intra-arterial injection of mescaline in adequate doses causes partial or complete paralysis in the dog neuromuscular preparation. Mescaline and curare tend to supplement one another with respect to their depressant actions on indirectly stimulated skeletal muscle. After complete blockade with mescaline, the muscle can readily be activated by direct stimulation. Following chronic denervation, the directly stimulated muscle fails to show an immediate depression of contractions when mescaline is administered. Adrenaline, KCl and prostigmine can oppose the paralyzing action of mescaline. The site of action of mescaline in producing paralysis is localized in the neuromuscular complex.
Sites of plasma albumin catabolism in the rat
Authors: Katz Joseph , Rosenfeld Sheldon , Sellers Alvin L.
Published: December 2017

The effects of splenectomy, partial and complete gastrectomy, partial and subtotal hepatectomy, and evisceration on the catabolism of I131-labeled screened and unscreened plasma albumin in rats was studied. Splenectomy and removal of jejunum and ileum had no effect, but complete enterectomy, hepatectomy, and evisceration depressed plasma albumin breakdown as compared to sham-operated controls. Plasma albumin breakdown was found to proceed at an appreciable rate in eviscerated rats, and it appears that up to half of albumin breakdown in the rat occurs in nonvisceral sites. In perfused rat liver unscreened iodoalbumin is rapidly degraded, but the breakdown of screened albumin is low, accounting for about 15% of total plasma albumin catabolism in vivo.
Blood pressure, heart rate, and adrenal catecholamines prior to ventricular fibrillation
Authors: Bass Noel M. , Glaviano Vincent V.
Published: December 2017

Heart rate, mean blood pressure, adrenal blood flow, and adrenal plasma adrenaline and noradrenaline were compared before and after ligation of the anterior descending coronary artery in dogs anesthetized with chloralose. One group of 12 dogs responded to acute coronary occlusion with a sudden and marked decrease in mean blood pressure (mean, 31%) and heart rate (mean, 18%) followed by an early onset (mean, 227 sec) of ventricular fibrillation. Another group of nine dogs responded with slight decreases in mean blood pressure (mean, 13%) and heart rate (mean, 5%), during which time ventricular fibrillation occurred late (mean, 30 min) or not at all. While the two groups were statistically different in mean blood pressure and heart rate, the minute output of adrenal catecholamines in either group was not found to be related to the early or late occurrence of ventricular fibrillation.
Atrioventricular pressures and their relationships during stellate stimulation
Authors: Ulmer Richard H. , Randall Walter C.
Published: December 2017

Pressures were recorded simultaneously from the four cardiac chambers in anesthetized, open-chest dogs during electrical stimulation of the stellate ganglion before and after bilateral vagotomy. Augmentation of atrial contraction was shown to accompany that in the ventricles by increased atrial pressures, as well as by the direct recording of atrial force. Fast-speed records revealed the augmentation was primarily in the a-wave. In some experiments mean atrial pressures increased slightly, in others they remained essentially unchanged, and, in still others, declined during stimulation. The particular response in any given animal was not predictable. There was no consistent relationship between the change in right and left mean atrial pressures, although they showed simultaneous augmentation in amplitude of the a-wave. The augmented a-wave resulted in a significant increment in the atrioventricular pressure gradient during late diastole, and thus contributed to increased ventricular filling. Mean pressures consistently increased in both right and left ventricles during stellate stimulation.
Relationship between tissue respiration and total metabolic rate in hypo- and normothermic rats
Authors: Fuhrman Frederick A. , Fuhrman Geraldine J. , Farr Douglas A. , Fail Jane H.
Published: December 2017

The metabolic rate of whole rats was determined at body temperatures of 38 and 18 C. Rats in one series were cooled without anesthesia by the method of Giaja; those in another series were cooled during light pentobarbital anesthesia. The mean metabolic rate of rats in both series at a body temperature of 18 C was about 25% that at 38 C. Rates of O2 consumption (Qo2) of skeletal muscle, skin, liver, kidney, and brain were determined in Krebs medium III at 38 and at 18 C. The sum of the rates of respiration of these organs was then obtained at both temperatures and is equal to the sum of the product of tissue Qo2 and organ weight. At 38 C the O2 consumption of these organs is 72.5% of the metabolic rate of the whole animal at that temperature, while at 18 C the sum of the organ respiration is 106% of the metabolic rate of the whole animal at that temperature. This may be accounted for by a decrease in the mass of metabolically active tissue during hypothermia and by a low temperature coefficient for the respiration of muscle.
Isometric relaxation of striated muscle
Authors: Norris Forbes H.
Published: December 2017

Isometric relaxation was studied in rat peroneal muscle after supramaximal stimulation of the muscle along its entire length. There appear to be three phases of relaxation. First is a period of slow tension decay which becomes more prominent between twitches and full tetani, but then seems independent of tension and fatigue. This phase might represent retardation of relaxation. After an inflection, the relaxation curves decay exponentially. This second phase is unchanged by several experimental conditions; at 36 C, the exponential decay factor has a mean value of 55 (with time in sec). When the muscle is greatly stretched, graphical analysis reveals another inflection and a slower, third phase of relaxation. With this exception, stretching and fatigue have little or no effect on the time course of isometric relaxation. Analysis of the second and third phases suggests passive restoration of a stretched viscous elastic system.
Effects of adrenocorticotropin and endotoxin on adrenal stimulation and resistance to infection
Authors: Nadel E. M. , Young B. , Hilgar A. , Mandell A.
Published: December 2017

Endotoxin elicited an increase in the urinary excretion of three unconjugated (free) polar corticosteroids in guinea pigs, similar to that observed following adrenocorticotropin (ACTH) administration. The analytical procedure employed ethyl acetate extraction of urine, followed by paper chromatographic separation (chloroform-formamide system) and measurement by the Porter-Sibler method. The larger portion of the increased excretion, following endotoxin, was attributable to the combined 6(ß)-hydroxycortisol and 2(α)-hydroxycortisol fractions, in comparison to that of cortisol alone. With repeated administration of endotoxin, there were increases in the free polar corticosteroid excretion, less than those observed originally. This decrease was attributed to concurrent stimulation and accumulative impairment of the adrenocorticoid secretory mechanism by endotoxin. Parallel experiments in mice demonstrated no sparing effect of the pretreatment with ACTH upon challenge with viable E. coli, in contrast to the protection afforded by pretreatment with endotoxin.
Effect of sodium pentobarbital on histamine stimulated gastric secretion
Authors: Skyring A. P. , Milton G. W. , Maxwell G. A.
Published: December 2017

The inhibitory effect of sodium pentobarbital on histamine stimulated gastric secretion was studied in Heidenhain pouch dogs. An intravenous injection of sodium pentobarbital in a dose of 26 mg/kg produced significant inhibition of secretion at dose levels of histamine from 5.5 µg/histamine base/kg/10 min to 22 µg/histamine base/kg/10 min. The degree of inhibition produced was inversely proportional to the dose of histamine used but was not dependent on the depth of anesthesia. It is concluded that this effect is probably a direct effect on the parietal cell.
Perfusion of particles through arachnoid villi of the monkey
Authors: Welch Keasley , Pollay Michael
Published: December 2017

By the perfusion of arachnoid villi in excised simian dura mater, the passage through the villi of colloidal gold (.2–.3 µ diam), polystyrene microspheres of 1.17 µ and 1.8 µ, yeast (3–6 µ), goat erythrocytes (4 µ) and monkey erythrocytes (7.5 µ) was demonstrated. Polystyrene microspheres in the 6.4–12.8-µ range were excluded from passage. During the perfusion of the particles an impedance to flow most often developed and the particles were demonstrated by later microscopic examination to be enmeshed in the villi. Upon perfusion of mixtures of various sizes there was not found to be discrimination in passage based on size as long as the particles were beneath threshold size. It is concluded that these observations confirm the surmise, made earlier on anatomical evidence, that the villi provide open communication between the meninges and the venous system.
Renal tubular effects of ammonium salts on electrolyte transport
Authors: Orloff Jack , Kahn Melvin , Brenes Luis
Published: December 2017

It has been established that ammonia salts exert a direct renal tubular effect in the chicken. The injection of ammonium chloride into the renal portal circulation produces a predominantly unilateral effect, characterized by inhibition of both the reabsorption of sodium, chloride, bicarbonate, and water and the secretion of potassium and hydrogen ions. An increase in total ammonia excretion was also observed. The inhibition of electrolyte and water transport is independent of the anion infused. Natriuresis and diuresis are produced by the ammonium salts of chloride, sulfate, nitrate, and acetate. The effect is not dependent upon the development of metabolic acidosis. Furthermore, an increase in endogenous ammonia production and excretion provided by the infusion of precursor amino acids does not interfere with electrolyte transport. Thus, the inhibitory effect of ammonium salts is probably a consequence of an increase in the concentration of ammonium ion in the peritubular circulation. The results are consistent with the thesis that ammonium ion may substitute for potassium on the linked sodium-potassium exchange pump on the contraluminal surface of the renal tubule cell.
Alteration of carotid occlusion response by anesthesia
Authors: Armstrong G. G. , Porter H. , Langston J. B.
Published: December 2017

Dogs under chloralose anesthesia show augmented reflex responses of systolic arterial pressure, mean arterial pressure, diastolic arterial pressure, and pulse rate to bilateral occlusion of the common carotid arteries over the responses of these same parameters before any anesthesia. Hyporeflexia, as indicated by these parameters, is observed when the anesthetic is chloralose and urethan, pentobarbital, or thiobarbital. Less variance in the responses as a result of alteration of the anesthetic level is observed with chloralose or pentobarbital anesthesia than with chloralose and urethan or thiobarbital anesthesia. If either chloralose or pentobarbital is to be used in studies involving the carotid sinus reflex, due consideration must be given to the 8% increase in response of mean arterial pressure under chloralose anesthesia as well as the 9% decrease in response of this same parameter under pentobarbital anesthesia.
Intestinal transport of phosphate: action of vitamin D, calcium, and potassium
Authors: Harrison Harold E. , Harrison Helen C.
Published: December 2017

Everted loops of rat small intestine incubated in vitro produce a concentration difference of inorganic phosphate between the solutions bathing the serosal and mucosal surfaces as the result of transport out of the mucosal solution against a concentration difference. Cyanide or anaerobiosis inhibits this process. The concentrative transport of phosphate requires the presence of calcium and is enhanced by increase of potassium concentration in the medium. Loops from vitamin D-treated rats develop higher concentration ratios of phosphate between serosal and mucosal solutions than loops from vitamin D-deficient animals when the concentrations of calcium and potassium in the medium are the same. Complete removal of calcium from the system by EDTA inhibits transfer of phosphate against a concentration difference and eliminates the vitamin D effect. The findings suggest that the concentrative transport of phosphate across the intestinal wall is activated by calcium and potassium and that potassium can not satisfy the requirement for calcium. The effect of vitamin D can be to increase the availability of calcium to the system through an action on the permeability of cell surfaces to calcium.
Serotonin release by hydrochloric acid: possibility of a feed-back mechanism
Authors: Resnick Robert H. , Gray Seymour J.
Published: December 2017

This investigation was carried out to determine whether the release of upper intestinal serotonin produced by hydrochloric acid perfusion was responsible for a subsequent inhibition of gastric secretion. To explore this possibility, gastric secretion in the pyloric-ligated rat was studied after the administration of varying quantities of serotonin through the rat portal vein. In another series of tests, the capacity of intestinally perfused hydrochloric acid to inhibit gastric secretion was studied in animals partially depleted of serotonin by reserpine or subjected to drug-induced chemical blockade of serotonin effect. Results indicate that serotonin infused through the portal vein does not alter gastric pH or secretory volume and that partial depletion of tissue serotonin or the use of serotonin antagonists does not prevent the intestinal suppression of gastric secretory function. It is therefore concluded that the intestinal release of serotonin is not a factor in the reduction of gastric acidity after HCl perfusion of the small intestine.
Total serum and liver cholesterol in germfree and conventional male rats
Authors: Wostmann B. S. , Wiech N. L.
Published: December 2017

Total serum and liver cholesterol values were determined in germfree and conventional Lobund strain male rats of various ages. The data indicate that in the absence of a microflora, serum cholesterol values are higher at an early age, to become slightly lower than found in conventional controls at the age of 100 days. In young, young adult, and old germfree rats, liver cholesterol values were always higher than in the conventional animals. It is speculated that better reabsorption of biliary cholic acid and cholesterol, unchanged because of the absence of a microflora, could be responsible for the higher liver cholesterol values found in the germfree animals.
Hemodynamic correlates of the fourth heart sound
Authors: Muiesan G. , MacCanon D. M. , Nunez-Dey D. , Bartolo G. Di
Published: December 2017

Intracardiac phonocardiographic characteristics of the atrial sounds and the relation of these vibrations to mechanical and electrical events of the cardiac cycle were studied in 21 dogs. Simultaneous recordings of intracardiac (from RA, LA, RV, and LV) and external phonocardiograms and equisensitive intracardiac pressures confirmed that the atrial sound is commonly formed by two main sets of vibrations: the first coincident with the onset of the atrial "a" wave, the second with its highest pressure peak. It is suggested that the first group of vibrations is usually due to atrial contraction and the second to ventricular filling. A short reversal of presystolic AV pressures after atrial relaxation occurred in some of the cases, suggesting that here a valvular mechanism was involved in the production of the late component of the atrial sound. The rapid intravenous infusion of saline generally increased the amplitude of the atrial sound and made evident the presence of a second component. The administration of drugs inducing systemic or pulmonary hypertension failed to give consistent changes in the amplitude and timing of the atrial sound. An asynchronism between right and left atrial sounds was demonstrated, the right-sided presystolic vibrations preceding those of the left heart by 0.026 sec (AS1) and 0.023 sec (AS2), respectively, in accordance with the earlier electrical activation and contraction of the right atrium.
Na+, K+, Ca++, and Mg++ action on coronary vascular resistance in the dog heart
Authors: Scott Jerry B. , Frohlich Edward D. , Hardin Robert A. , Haddy Francis J.
Published: December 2017

Local effects of major cations on coronary vascular resistance were studied in the beating dog heart. This was accomplished by shunting the blood around the heart and lungs, clamping the arch of the aorta and perfusing arterial blood at a constant rate into the ascending aorta. Perfusion pressure was measured during intracoronary infusion of isotonic solutions of NaCl, KCl, CaCl2, MgCl2, and MgSO4 and hypertonic solutions of NaCl and KCl at rates which raised cation concentrations in coronary blood without significantly affecting concentrations generally within the body. Coronary vascular resistance decreased as a function of the infusion rate of isotonic solutions of KCl, MgCl2, and MgSO4 and increased as a function of the infusion rate of an isotonic solution of CaCl2. Isotonic NaCl had no effect. Resistance changes occurred before measurable change in the proportion of a minute spent in electrical systole by the ventricle. These findings, together with those previously reported for the dog foreleg, suggest that the coronary vascular bed is actively dilated by localized slight increase in plasma concentration of K or Mg and actively constricted by localized slight increase in plasma concentration of Ca.
Effects of calcium deficiency and excess on transmembrane potentials in frog heart
Authors: Ware Frederick
Published: December 2017

The effects of severe calcium deficiency and calcium excess on transmembrane potentials in isolated frog ventricular strips have been investigated. Resting potential rose about 5 mv above normal during perfusion with three times normal calcium and fell about 4 mv below normal during exposure to calcium-free Clark's solution. Mean overshoot rose about 3 mv during calcium lack, but was unaffected by excess calcium. Maximum depolarization rate increased about 20% during calcium deprivation and fell a similar amount during high calcium perfusion. However, the membrane potential at the moment of maximum depolarization rate was unchanged from normal by either experimental solution. High calcium augmented the "spike" and "plateau" during repolarization, while calcium deficiency abolished the spike, producing "hump-backed" action potentials with prolonged membrane reversal. These results are discussed, especially in relation to possible permeability changes during upstroke of the action potential.
Oxidative phosphorylation in magnesium and potassium deficiency in the rat
Authors: Beechey R. B. , Alcock N. W. , MacIntyre I.
Published: December 2017

Heart sarcosomes were isolated from magnesium-deficient, potassium-deficient, and normal control rats. Two methods of isolation were used. P/O ratios were determined after measuring the oxygen consumption polarometrically in some cases and mano-metrically in others. No matter which method of isolation was used, or which method of determining the oxygen consumption, no difference could be demonstrated between the ratios obtained using sarcosomes isolated from the control rats and those isolated from the magnesium-deficient or the potassium-deficient rats. The results obtained in magnesium deficiency are not in agreement with those reported in 1957 by Vitale, Nakamura, and Hegsted ( J. Biol. Chem. 228: 573, 1957), who found lowered P/O ratios were associated with magnesium deficiency. While no satisfactory explanation can be found for the differences reported, it is suggested that they can only be ascribed to differences in technique.
Steady state material transfer through biological barriers
Authors: Nims Leslie F.
Published: December 2017

A general theory of material transfer through biological barriers, based on the idea that diffusion processes obey Newton's laws of motion, is outlined. The distribution of permeant ions in the system phase α, barrier, phase ß, when the system is in a stationary state, is discussed. The theory predicts that the logarithms of the concentration ratios of ion pairs in the two phases should be nearly proportional to the flow of water through the barrier when stationary states of the first order due to steady flows of water are established. The theory further predicts that, given similar conditions, the ratio of the logarithms of the concentration ratios of two ion pairs in systems containing two or more salts should be approximately equal to the inverse ratio of the diffusion coefficients of the respective salts in water and hence quasi-invariant.
Ion distribution patterns in stationary state systems
Authors: Nims Leslie F. , Thurber Robert E.
Published: December 2017

The distribution of ions between two homogeneous phases separated by a permeable barrier has been studied when the transfer system is in a stationary state of the first order resulting from a constant flow of water through the barrier. As predicted by a general theory of material transfer through a barrier, outlined in the preceding paper, it was found that the logarithm of the concentration ratio of ion pairs in the phases adjoining the barrier was nearly proportional to the flow of water through the barrier. Also, as predicted, it was found that the ratio of the logarithms of the concentration ratios of two pairs of ion pairs was quasi-invariant and independent of the flow rate of water when the system contained two or more salts. The numerical value of the quasi-invariant ratios, characteristic of stationary states produced by a flow of water, was approximately equal to the inverse ratio of the diffusion coefficients in water of the two salts comprising the ion pairs.
Vascular changes associated with development of irreversible endotoxin shock
Authors: Hinshaw Lerner B. , Vick James A. , Jordan Margaret M. , Wittmers Lorentz E.
Published: December 2017

Recent reports from this laboratory have described the hemodynamic effects of endotoxin in the dog, cat, rabbit, and monkey. To determine the role of peripheral vascular changes in the onset of irreversible shock, isolated denervated dog legs were perfused by means of a pump-lung or dog-pump apparatus. Following endotoxin, dogs liberated vasoactive substances which had profound effects on the perfused organ. Large changes in leg arterial resistance and increases in small vein pressure were seen, which resulted in the formation of edema. Vascular responses of legs to pressor agents in late shock appear abnormal in that venous resistance increases while arterial responses diminish. This, in conjunction with the increased level and activity of histamine, may account for the development of the irreversible period. These findings explain the reported harmful effects of pressor agents when used therapeutically and provide a rationale for the protective actions of adrenergic and histamine-blocking drugs. The study serves to underscore the significance of recently reported findings on the primate in endotoxin shock.
Utilization of C14-labeled cottonseed oil emulsion by normal and thermally injured rats
Authors: Milstein Seymour W.
Published: December 2017

The rates of oxidation, blood clearance, and deposition of a C14-labeled cottonseed oil emulsion (Lipomul I.V.) injected intravenously into normal, burned, and fasted rats have been determined. Standard thermal injury with varying postburn intervals did not change the rate of oxidation from normal, while moderate fasting of unburned rats produced slightly elevated rates. Small increases above normal clearance times were induced in both burned and moderately fasted animals. A significant depression from normal rates of deposition was observed in fasted rats, while the marked decrease in deposition seen in the early postburn course returned to normal levels in about 3 weeks. Animals pair-fed against one group of burned mates showed essentially normal fat deposition.
Effect of phlorizin on hepatic glucose output
Authors: Kolodny Edwin H. , Kline Robert , Altszuler Norman
Published: December 2017

Using phlorizin as an experimental tool, an investigation of the mechanisms responsible for the maintenance of plasma glucose levels was undertaken. Infusion of phlorizin has been shown to produce a prompt glucosuria and increase in hepatic glucose output (HGO), but without discernable hypoglycemia. This raises the question as to the nature of the stimulus for the increased HGO. The effect of phlorizin on net HGO was studied in anesthetized dogs with indwelling catheters in the portal and hepatic veins. Infusion of phlorizin into normal dogs produced a prompt glucosuria and a concomitant increase in HGO, without significant changes in the plasma glucose concentration in the portal vein. In functionally nephrectomized dogs, phlorizin did not change HGO nor circulating glucose levels. In dogs with intact kidneys, when glucosuria was prevented by urine recirculation into the inferior vena cava, the infusion of phlorizin again failed to alter HGO or circulating glucose levels. The data indicate that the phlorizin-induced increase in HGO is dependent on loss of glucose from the body. The enhancement of HGO could not be ascribed to a direct stimulation of the liver, kidney, or endocrine glands, or to an impairment of glucose utilization. Possible mechanisms to explain this effect of phlorizin are discussed.
Effect of acetazolamide on dog parotid saliva
Authors: Brusilow Saul W. , Diaz Carmen L.
Published: December 2017

Canine parotid saliva was obtained at varying secretory rates by the stimulation of the postganglionic parasympathetic nerve. Analysis revealed this secretion to have a CO2 content of about 20–30 mEq/liter at low rates of salivary flow to 50– 60 mEq/liter at high flow rates. After the intravenous administration of acetazolamide, the CO2 content at high flow did not rise much above those levels attained at low secretory rates. Acetazolamide also caused decrease of sodium concentration and an increase in chloride concentration at high rates of secretion.
Determinants of coronary flow and myocardial oxygen consumption
Authors: Feinberg H. , Katz L. N. , Boyd E.
Published: December 2017

The effect of altering hemodynamic parameters and blood milieu on myocardial oxygen extraction (O2E) was observed in an improved preparation of the anesthetized, open-chested dog. O2E remains at or near its high level for at least 40 min despite shifts in pH and cardiac input and sustained aortic compression. Aortic compression at constant cardiac input is associated with a moderate O2E decrease. Alternate aortic compression and release accompanied by induced shifts in pH and pCO2 caused an earlier and accelerated O2E decline. Coronary flow (CF) ordinarily is at a minimum for a given cardiac effort and rises when O2E declines. The O2E fall and CF increase are considered evidence of loss of coronary vascular tone. Despite shifts between CF and O2E, myocardial O2 consumption (O2C) remains closely associated with the cardiac effort index (mean aortic pressure x heart rate—HR·BP). Shifts in cardiac input, pH, and/or pCO2 have minimal effects on this O2C/HR·BP relationship. The significance of HR·BP as an energy utilization index is discussed.
Correlation between respiratory reflex and acetylcholine content of pons and medulla
Authors: Metz Bernard
Published: December 2017

Experiments indicate that there is a significant correlation between respiratory function (as measured by the reflex response to electrical stimulation of Hering's nerve) and the total acetylcholine (ACh) concentrations in the pons and medulla, after intravenous administration of the hemicholinium, HC-3 (α,α', dimethylethanolamino 4,4' biacetophenone), a drug which inhibits the synthesis of ACh. With a decreasing respiratory reflex response there is a corresponding progressive and gradual decrease in the total ACh content in the pons and medulla. These experiments lend additional support to the hypothesis of the participation of a cholinergic factor in central respiratory control, particularly in view of the fact that these investigations are in harmony with earlier studies in which other biochemical rearrangements were induced within the cholinergic system.
Response of isolated perfused dog kidneys to epinephrine
Authors: Worthen David M. , Anderson Quentin N. , Hinshaw Lerner B.
Published: December 2017

To investigate the renal vascular changes induced by epinephrine, 21 isolated dog kidneys were perfused at constant pressure. Single injections and constant infusions of epinephrine were administered. Changes in blood and urine flow and arterial and intrarenal venous pressures were measured. Changes in renal volume were estimated with a kidney-weighing device, and determinations of cation concentrations were carried out. Data do not support the view that low doses of epinephrine cause diuresis. The previously reported afferent dilation and efferent constriction after epinephrine administration were not found in this investigation. Both increased and decreased urine flows were noted at low doses of epinephrine, whereas a fall in urine flow was consistently seen at high doses. The primary vascular effect of epinephrine is presumably on the afferent arteriole, since there was no consistent diuresis, no increase in kidney weight, a decrease in blood flow, and a decrease in filtration. Electrolyte excretion was not directly influenced by epinephrine. The pressure in the ureter was changed by epinephrine.
Autoregulation of blood flow in skeletal muscle during increased metabolic activity
Authors: Stainsby Wendell N.
Published: December 2017

The effect of increased metabolic rate on autoregulation of blood flow in skeletal muscle was investigated by stimulating muscle to contract. At elevated metabolic rates good autoregulation of blood flow was observed but at higher blood flow levels than those observed in resting muscle. The degree of autoregulation in the contracting muscle was at least as great as in resting muscle. It would appear that a close link with metabolism is involved in the mechanisms associated with autoregulation of blood flow.
Vascular resistance and venous blood K+ during hypothermia in skeletal muscle
Authors: Yonce Lloyd R. , Dykers John R. , McGee James W.
Published: December 2017

Parameters of vascular resistance, perfusion pressure, and blood flow were measured as the temperature of the isolated gracilis (dog) muscle and perfusing blood was lowered continuously from approximately 37.5 C to 25 C. The rate of change of temperature varied from 4.20 C/min to 0.13 C/min. At the rapid rate of lowering the temperature, the vascular resistance of the muscle decreased and then increased. As the rate of lowering the temperature was decreased this response progressively changed to only an increased resistance. Eight experiments were performed in which the potassium concentration of the venous whole blood and plasma was determined as the temperature of the muscle was lowered. There was no significant change in the mean potassium concentration of the venous whole blood during hypothermia. However, the potassium concentration of the plasma decreased continuously as the temperature was lowered. Correlation coefficients between the change in peripheral resistance and the potassium concentration of the plasma appeared to be significant at the 5% level.
Excretion of tryptamine and indole-3-acetic acid in urine of rats with intestinal diverticula
Authors: Donaldson Robert M.
Published: December 2017

The urinary excretion of indoleacetic acid, but not of tryptamine, is increased in rats with localized intestinal stasis resulting from the surgical formation of midintestinal diverticula. Significant quantities of tryptamine, however, are produced within the intestinal pouches of these animals. When the conversion of tryptamine to indoleacetic acid is maximally inhibited with iproniazid, tryptamine accumulates in the urine of the rats with diverticula to the same extent as it does in control animals. The monoamine oxidase activity of tissues from rats with diverticula is neither increased nor resistant to iproniazid inhibition. Injection of large quantities of tryptamine directly into the intestinal pouches produced no significant increase in urinary tryptamine or indoleacetic acid. It therefore appears that tryptamine produced within the diverticula does not significantly contribute to the indoleacetic acid appearing in the urine of these rats.
Renal excretion of choline in the dog
Authors: Vander Arthur J.
Published: December 2017

Experiments on dogs, with clearance and stop flow techniques, demonstrated that choline is reabsorbed and secreted by the proximal tubule, both processes being active. These processes seem to occur simultaneously, net reabsorption predominating at normal plasma choline concentrations and net secretion often becoming manifest when plasma choline was elevated. Secretion could be inhibited by either cyanine dye no. 863 or a hemicholinium. Transport rates were extremely variable in different animals and constant in a single animal only for several hours. The distal nephron was found to be impermeable to choline. The degree of proximal permeability could not be quantitated. Passive transport did not appear to be significantly involved in choline excretion.
Age and diet effect on thyroid-serum ratio, PBI, and thyroidal iodine and histology in rodents
Authors: Silverstein E. , Yamamoto R. S. , Mickelsen O.
Published: December 2017

The thyroid-serum (T/S) ratio and relative thyroid weight of rats made obese by high fat diet were lower, absolute thyroid weight and thyroidal iodine concentration higher, and thyroid follicles larger and more filled with colloid than in rats on control diet. There was a tendency in rats and mice for the T/S ratio to reach a peak value at 10–18 weeks of age which was not observed in rats on a high fat diet. Rats at 4–5 weeks of age tended to have a relatively larger thyroid, lower T/S ratio, and lower thyroidal idoine concentration than older animals.
Glucose metabolism in the lactating beagle dog
Authors: Luick Jack R. , Black Arthur L. , Parker Harold R. , Simesen Mogens G.
Published: December 2017

A study was made of the role of glucose as an oxidizable substrate and as a source of C for the synthesis of milk using lactating beagle dogs. Uniformly C14-labeled glucose was used as a tracer of these metabolic pathways. Our data indicate that the labeled glucose was completely eliminated from the dog's body within 24 hr after injection. Sixty percent of the injected dose appeared in the expired CO2, 40% in the various milk products. Comparison of the integrated specific activity of plasma glucose with that of expired CO2 indicates that 36% of the dog's energy requirement is met by the oxidation of glucose. This presumably means that the catabolism of noncarbohydrate substances must be of considerable importance to the energy metabolism of not only the fasted dog and the diabetic dog, as has been demonstrated earlier, but also of the fed dog. We have also shown that 68–100% of the C required for the synthesis of lactose is derived from plasma glucose. In addition, plasma glucose contributes 7.2–12% of milk protein C and 5.1–8.7% of milk fat C. These results are compared with similar data obtained earlier in our laboratory using lactating cows and sows.
Glucocorticoid effects on respiration and metabolism by rat liver homogenates
Authors: Goetsch Dennis D. , McDonald L. E.
Published: December 2017

The effects of glucocorticoid administration on oxygen uptake, glucose and glycogen disappearance, lactic acid formation, and inorganic phosphate and protein levels in rat liver homogenates have been studied. A single injection of hydrocortisone, prednisolone, or 9 α-fluoroprednisolone 5 hr before sacrifice resulted in a highly significant increase in oxygen uptake by rat liver homogenates, whereas chronic administration of prednisolone daily for 7 days caused a marked inhibition in homogenate respiration. Glycolytic rate did not appear to be affected by single injections since endogenous carbohydrate utilization was similar in liver homogenates prepared from control and treated animals. Incubation of liver homogenates under aerobic conditions disclosed that inorganic phosphate levels were decreased in homogenates from corticoid-treated rats, whereas these levels were similar in treated and control liver homogenates incubated under nitrogen. Under anaerobic conditions, liver homogenates from treated rats accumulated lactic acid more rapidly than untreated liver homogenates. Glucocorticoid treatment did not appear to affect protein disappearance since no differences between protein levels in treated and untreated rat liver homogenates were detected following incubation.
Effects of temperature on membrane potentials of lobster giant axon
Authors: Dalton J. C. , Hendrix D. E.
Published: December 2017

In the range 2–20 C, the resting potential of the lobster axon shows a greater increase with increase of temperature than can be explained by the Nernst relationship. Action potential also shows an initial increase with temperature, peaks at about 16 C, then decreases. Maximum rates of rise and fall of the action potential increase with temperature increase; duration of the propagated action potential decreases. Afterpotentials in this preparation are in the form of a delayed repolarization; as temperature is increased, the magnitude of the afterpotentials increases, as does the rate of repolarization. These results have been compared with results already available for the squid axon. Differences between the two preparations occur in the relationship of the resting potential, action potential magnitude, and afterpotentials to temperature. It is suggested that these differences may be explained by the presence of a temperature-dependent fraction of the resting potential in the lobster axon which is not present, or is inactive, in the squid axon.
Vagotomy-induced pulmonary edema in the guinea pig
Authors: Rech R. H. , Borison H. L.
Published: December 2017

A method is described for measuring alterations in total thoracic mechanics during the development of vagotomy-induced lung edema in the unanesthetized guinea pig. Influences of restraint, tracheotomy, and positive-pressure ventilation on lung edema were determined prior to analysis of respiratory function. Volume-pressure relationship was obtained at inflation volumes from 2–8 ml delivered at a variety of frequencies and flow rates at intervals before and after bilateral vagotomy. Development of edema was characterized by a progressive upward shift in pressure with negligible change in compliance (ΔV/ΔP) above the tidal volume range. This shift was due mostly to an increase in the elastic component and scarcely at all to an increase in the resistive component of the volume-pressure function. Measurements revealed that the edema fulminates terminally. Good correlation was found between extent of pressure shift and increase of lung-to-body weight ratio, thereby substantiating the validity of the measurement for in vivo evaluation of degree of pulmonary edema. Attempt to use lung specific gravity as a postmortem criterion of lung edema failed because of inconstant trapping of air.
Role of hypotension in altering blood coagulability after endotoxin
Authors: Carozza Frank A. , Hills J. Dixon
Published: December 2017

Because hypotension, regardless of etiology, profoundly influences blood coagulation, the role of hypotension in altering blood coagulability after endotoxin was investigated. By means of femoral artery catheterization, serial whole blood clotting times were determined in siliconized tubes at 37 C and correlated with mean arterial blood pressures in 1-kg albino rabbits. After duplicate base-line determinations, 200 µg/kg E. coli endotoxin was injected intravenously into nine animals; this quantity of endotoxin was the largest dose not lethal to normal rabbits of the strain employed. Nine control animals received isotonic saline. Blood from the endotoxin-treated group exhibited some accelerated coagulability between 1–2 hr after endotoxin injection and became significantly hypercoagulable ( P < 0.05) during the 3rd and 4th hr. The observed hypercoagulability could not be correlated with the hypotensive arterial blood pressure levels, the mean coefficient of correlation being –0.18. These data suggest that endotoxin-induced hypercoagulability in the rabbit results from specific reactions that are mediated by mechanisms distinct from those known to operate during the hypotensive state per se.
Pulse contour changes in carotid and foreleg arterial systems
Authors: Meisner J. E. , Remington J. W.
Published: December 2017

In both the carotid and foreleg vessels of the dog the whole of the aortic pulse seemed propagated at a uniform velocity. In the upper carotid and axillary arteries, a narrowed systolic peak developed in transit; this peak was reached at the same time through the length of the elastic vessels. In the muscular brachial artery, the peak was propagated without clear change. Occlusions of various branches of the leg bed gave no firm clue to the origin of this narrowed peak, for they tended simply to induce pressure oscillations in the axillary vessel which usually obscured the normal pulse form. A similar pulse mapping in a common carotid artery occluded 12–15 cm from its origin sometimes showed evidence of a propagated reflected wave. At other times, as much as 6 cm of the vessel acted as a single vibrating unit, with identically timed waves. Length of the occluded carotid artery could not be told from the peak-to-peak intervals seen on the pulses.
Comparison of distribution spaces for labeled and unlabeled cells and plasma in dogs
Authors: Lawson Hampden C. , Shanklin J. Day , Chacalos E. H.
Published: December 2017

Distribution spaces for T-1824 ( PVl) and for P32-labeled red cells ( CVl) were determined in intact barbitalized dogs by conventional methods. One hour after injection of these two labels, their circulating concentrations were reduced by a paced simultaneous infusion of a large volume of unlabeled autologous whole blood, and withdrawal of an equal volume from the circulation. Distribution spaces were calculated from the decrease in the respective label concentrations, for the infused unlabeled plasma ( PVd) and unlabeled cells ( CVd). When corrections were made for external volume changes due to sampling, PVl was in good agreement with PVd, and CVl with CVd. When donor blood was substituted for autologous blood in this procedure, agreement was usually not observed. When blood volume was expanded by infusing autologous blood without preliminary or simultaneous withdrawal, CVd agreed with CVl, but large differences were observed between PVd and PVl. The two plasma values were brought into somewhat better, though not complete, agreement by preliminary withdrawal, but CVd was usually made less than CVl.
Reabsorption and secretion of ι-malic acid in kidney proximal tubule
Authors: Vishwakarma P.
Published: December 2017

The ι-malic excretion pattern was studied in the dog using the "stop flow" method. During ι-malic and fumaric infusions, a net reabsorption of ι-malic acid was seen only in the proximal tubule. This reabsorption occurred against a massive concentration gradient and, therefore, was justifiably termed active reabsorption. Infusion of succinate produced a net secretion of ι-malic. This was also confined to the proximal tubule. The secretion, however, occurred in the direction of the concentration gradient and, therefore, was probably a diffusion phenomenon. The secretion could be inhibited by malonate. It was concluded that the renal transports of ι-malic acid are intimately related to the operation of the tricarboxylic acid cycle.