bluuebunny/crossref_metadata_2025 huggingface dataset:
Entrained ion transport systems generate the membrane component of chaotic agonist-induced vasomotion
Authors: Edwards D. H. , Griffith T. M.
Published: December 2017

We have analyzed the contribution of membrane ion transport systems to chaotic vasomotion induced by histamine in isolated rabbit ear resistance arteries. Dynamic complexity was monitored as a fractal correlation dimension that provides an estimate of the minimum number of control variables contributing to an irregular time series and generally took a value between 2 and 4. A distinct subcomponent of the overall oscillatory activity (frequency approximately 0.06 Hz) was selectively suppressed by blockade of Ca(2+)-activated K+ channels (KCa) with tetraethylammonium, Ca(2+)-activated Cl- channels with low extracellular Cl- concentration and niflumic acid, the Na(+)-K+ adenosine-triphosphatase (ATPase) with ouabain, and Na+/Ca2+ exchange with low-Na+ buffer. Each of these interventions caused a fall in average fractal dimension to a value < 2, whereas inhibition of voltage-dependent K+ channels with 4-aminopyridine or the Ca(2+)-ATPase extrusion pump with vanadate were without effect on the form and complexity of the vasomotion. There was no systematic correlation between the changes in fractal dimension induced by the various interventions and their effects on perfusion pressure. Our findings suggest that nonlinearity in the kinetics of multiple coupled ion transport systems leads to entrainment and the emergence of a composite membrane oscillator, thus accounting for the low fractal dimension of the vasomotion observed in these arteries.
Pregnancy augments uteroplacental vascular endothelial growth factor gene expression and vasodilator effects
Authors: Ni Y. , May V. , Braas K. , Osol G.
Published: December 2017

This study examined a potential role for vascular endothelial growth factor (VEGF) in uterine artery remodeling and vasodilation during pregnancy. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect VEGF mRNA in uterine tissues from nonpregnant (NP), midpregnant (MP, 15-16 days), and late-pregnant (LP, 19-21 days) rats and in placentas from MP and LP rats. VEGF mRNA levels in uteri and placentas were determined by Northern blotting, and the vasorelaxant activity of recombinant human VEGF (rh-VEGF) was tested and compared in isolated uterine arteries from LP and NP animals. VEGF120 and VEGF164 were the major isoforms detected in uterine tissues; all members of the VEGF family (VEGF120, VEGF164, VEGF188, and VEGF205) were expressed in LP placentas. VEGF mRNA levels increased 60% in MP and 80% in LP above those in NP (P < 0.05) in uterine tissues; VEGF mRNA levels were also detectable in placentas and elevated approximately fivefold in LP vs. MP tissues (P < 0.01). Phenylephrine-preconstricted uterine arcuate arteries (NP and LP) dilated in response to rhVEGF, an effect that was completely abolished by endothelial denudation or pretreatment with genistein, a tyrosine kinase inhibitor. The magnitude of dilation to an intermediate concentration of rhVEGF (1 nM) was greater in LP than in NP vessels (55 +/- 8 vs. 24 +/- 11%; P < 0.05), and this effect was diminished comparably in both groups (approximately 60% by N omega-nitro-L-arginine, an inhibitor of nitric oxide synthesis. These results suggest that VEGF may play a role in the vascular remodeling and vasodilation that lead to decreased uterine vascular resistance and increased uterine blood flow during pregnancy.
In vivo aortic wall characteristics at the early stage of atherosclerosis in rabbits
Authors: Hironaka K. , Yano M. , Kohno M. , Tanigawa T. , Obayashi M. , Konishi M. , Umemoto S. , Matsuzaki M.
Published: December 2017

To assess whether vascular responsiveness to alpha-receptor agonist is altered at the early stage of atherosclerosis, in vivo aortic pressure-diameter relationship of the aorta over a wide range of pressures was analyzed before and after the acute administration of alpha-receptor agonist (phenylephrine) in nine hypercholesterolemic fat-fed (7-wk-old) rabbits and eight normal diet-fed (7-wk-old) rabbits. In hypercholesterolemic fat-fed rabbits, there was no major structural change in the aortic wall except fatty streak, despite a marked increase in the level of plasma cholesterol, indicating the early stage of atherosclerosis of the aorta. By using a modified three-element Maxwell model, diastolic stress-strain relationship was computed after applying several assumptions to the actual aortic pressure-diameter relationship. After the intravenous administration of phenylephrine at a rate of 5 micrograms.kg-1.min-1, the stress (ordinate)-strain (abscissa) relationship curves were shifted to the left, indicating the activation of aortic smooth muscle by phenylephrine. The difference between the stress before and after phenylephrine showed a single peak at a certain strain. The peak difference in the stress was smaller in hypercholesterolemic fat-fed rabbits than in normal diet-fed rabbits, indicating the reduction of vascular responsiveness at the early stage of atherosclerosis of the aorta.
Ca2+ handling by rat myocardium exposed to ATP solutions of different [Ca2+] and Ca2+ buffering capacity
Authors: Kabbara A. A. , Stephenson D. G.
Published: December 2017

Cardiac preparations from the right ventricular wall of rats were exposed to ATP-containing solutions of different Ca2+ concentrations ([Ca2+]) and Ca2+ buffering capacity to determine whether such treatments affected the Ca2+ handling properties of the cardiac muscle. Exposure to 8 mM extracellular ATP (ATP0) elicited sustained, near-maximal contractures that were due to Ca2+ entry from the extracellular environment and severely diminished cardiac excitability in a partially reversible manner. At 1 mM ATP0, there was a sustained rise in diastolic force and intracellular [Ca2+] and a marked, partially reversible change in the stimulation-induced Ca2+ transients measured with fura 2. A large, transient contracture was also observed when the intact ventricular preparations were transferred from the normal physiological solution to an ATP-containing (8 mM) relaxing solution (ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid < or = 0.2 mM, < 10 nM Ca2+) with or without saponin (50 micrograms/ml). The ATP0-induced contractures were dependent on the prevalent conditions with respect to [Ca2+] and Ca2+ buffering capacity of the solutions and were associated with heavy Ca2+ loading of the sarcoplasmic reticulum (SR) and mitochondria, a less leaky SR, and a reduced SR sensitivity to the SR Ca2+ pump blocker 2,5-di-tert-butyl hydroquinone. The results indicate that the Ca2+ handling properties and the electrical excitability of ventricular preparations can be markedly modified by exposure to ATP0 and that conditions prevalent during skinning with saponin are important in determining the properties of the intracellular Ca2+ stores.
Mitochondrial calcium content in isolated perfused heart: effects of inotropic stimulation
Authors: Moravec C. S. , Desnoyer R. W. , Milovanovic M. , Schluchter M. D. , Bond M.
Published: December 2017

We tested the hypothesis that in the intact heart, mitochondrial metabolism is activated by mitochondrial Ca2+ uptake during increased work. We measured left ventricular pressure (LVP), pyruvate dehydrogenase (PDH) activity, and mitochondrial and A band elemental content by electron probe microanalysis (EPMA) in Langendorff-perfused hamster hearts under control conditions, after isoproterenol (10(-6) M) stimulation, and after increasing perfusion pressure from 60 to 100 mmHg. Hearts were rapidly frozen, then EPMA was performed on cryosections cut from the surface of the frozen hearts; PDH activity was measured from the same area. Isoproterenol and elevated perfusion pressure increased LVP by 185 +/- 21 and 58 +/- 14%, respectively, versus controls. PDH activity increased from 10.4 +/- 1.5 (mean +/- SE) nmol.min-1. mg protein-1 (controls) to 21.6 +/- 3.5 (isoproterenol) and 18.5 +/- 3.2 nmol.min-1.mg protein-1 (increased perfusion pressure). There was no significant change in mitochondrial Ca1 in response to isoproterenol [1.2 +/- 0.1 (mean +/- SE) mmol/kg dry wt] or increased perfusion pressure (1.1 +/- 0.1) versus controls (1.0 +/- 0.1). These results suggest that, in the intact heart, mechanisms other than mitochondrial Ca2+ uptake may contribute to PDH activation and increased cardiac work.
c-Ha-rasEJtransfection in vascular smooth muscle cells circumvents PKC requirement during mitogenic signaling
Authors: Weber Thomas J. , Ramos Kenneth S.
Published: December 2017

In view of the prominent role of protein kinase C (PKC) in the regulation of vascular smooth muscle cell (VSMC) growth and differentiation, the present studies were conducted to assess the impact of c-Ha-rasEJtransfection on PKC-dependent growth programming. PKC activity was elevated in the cytosolic and particulate compartments of c-Ha-rasEJVSMC, relative to naive or pSV2neo vector controls. Constitutive and 12- O-tetradecanoyl phorbol 13-acetate (TPA)-inducible binding to a TPA-responsive element (TRE) was also enhanced in c-Ha-rasEJVSMC. Fetal bovine serum (FBS) did not increase TRE-binding activity in serum-starved c-Ha-rasEJVSMC but increased TRE-binding activity in pSV2neo VSMC. FBS-mediated TRE-binding activity was dramatically decreased in serum-starved pSV2neo VSMC pretreated with 100 ng/ml TPA for 24 h to downregulate PKC activity. c-Ha-rasEJVSMC exhibited a marked proliferative advantage over controls under both restrictive and growth-permissive serum conditions. PKC downregulation did not influence the mitogenic response to serum in c-Ha-rasEJVSMC but ablated [3H]thymidine incorporation into DNA in naive or pSV2neo vector counterparts. Western blot analysis demonstrated increased expression of extracellular signal-regulated kinase 2 (ERK2), but not ERK1, in c-Ha-rasEJVSMC, relative to pSV2neo control. Immunoblots of serum-starved and PKC-depleted c-Ha-rasEJVSMC demonstrated a dramatic increase in the phosphorylated form of ERK2, relative to pSV2neo controls. These data suggest that oncogenic c-Ha-rasEJcircumvents a requirement for a TPA-responsive PKC isoform(s) during mitogenic stimulation of VSMC.
Age effects on interrelationships between lung volume and heart rate during standing
Authors: Stanley Garrett , Verotta Davide , Craft Noah , Siegel Ronald A. , Schwartz Janice B.
Published: December 2017

To determine the effects of aging and posture on the relationship between respiration and heart rate (HR), we collected 5 min of lung volume and R-R interval data from 7 young (27 ± 3 yr, mean ± SD) and 10 old (69 ± 6 yr) healthy humans during spontaneous breathing while they were supine (SU) and standing (ST). Lung volume and HR power spectra and transfer functions between lung volume and HR were estimated. Age and position effects and age-position interactions were determined by analysis of variance for repeated measures. Older subjects had a lower and more variable respiration rate ( P < 0.03, P < 0.04), but both age groups exhibited decreased rate of respiration and increased tidal volume with ST ( P < 0.05, P < 0.005). ST decreased lung volume-to-HR transfer function magnitude in both groups ( P < 0.07). The more marked age-related differences were in phase angle. Both SU and ST phase angles were greater in older subjects ( P < 0.003). ST decreased phase angle in young but increased phase angle in older subjects ( P < 0.001). In conclusion, respiration, and respiration-HR interrelationships are altered by aging, with increased time delays between lung volume and HR and altered relationships with ST.
Elevated right atrial pressure does not reduce collateral blood flow to ischemic myocardium
Authors: Yu Ying , Tune Johnathan D. , Downey H. Fred
Published: December 2017

Right atrial pressure (RAP) may become substantially elevated during heart failure and has been reported to reduce collateral flow to the ischemic myocardium of isolated hearts. The effect of elevated RAP on blood flow to collateral-dependent and normal myocardium of in situ hearts was studied in 20 open-chest anesthetized dogs with acute occlusion of the left anterior descending coronary artery. Regional myocardial blood flow was measured with radioactive microspheres while RAP was elevated by restricting right ventricular (RV) outflow with constant aortic pressure. Increasing RAP from 3.8 ± 0.5 to 21.5 ± 0.8 and then to 34.3 ± 0.9 mmHg did not reduce blood flow to any transmural region of LV normal or collateral-dependent myocardium. Further elevation of RAP to 49.3 ± 1.1 mmHg reduced subepicardial but not subendocardial collateral flow. Blood flow to normal RV increased. Retrograde flow and peripheral coronary pressure increased as RAP was elevated. Previously injected 11-μm microspheres were present in the retrograde flow when RAP was elevated; thus retrograde capillary flow contributed to the retrograde flow. The results explain discrepancies among previous reports, and they are consistent with a waterfall phenomenon in the coronary collateral circulation.
Use of microdialysis for monitoring sympathetic and parasympathetic innervation of heart in conscious rats
Authors: Cremers T. I. F. H. , Teisman A. C. H. , Van Gilst W. H. , Westerink B. H. C.
Published: December 2017

A microdialysis method was developed to sample norepinephrine and acetylcholine from the heart of freely moving rats. A flexible dialysis fiber (length 14 mm), with a copper wire inserted inside, was implanted into the heart. Extracellular norepinephrine was detectable for at least 72 h after implantation. Basal output levels 24 h after surgery were 140 pg/ml when corrected for in vitro recovery. Evidence was provided that the major part of norepinephrine in dialysates is derived from local neurotransmission. Acetylcholine was only detectable in cardiac dialysates when an esterase inhibitor was infused. Corrected basal output levels 24 h after surgery were 223 pg/ml when neostigmine was coinfused in a concentration of 100 μmol/l. In addition, the presence of local muscarinic autoreceptors on cholinergic neurons in the heart was shown. It is concluded that microdialysis is a reliable method that can be used to study the innervation of the heart in subchronic preparations in freely moving rats.
Platelet-derived lysophosphatidic acid decreases endothelial permeability in vitro
Authors: Alexander J. S. , Patton W. F. , Christman B. W. , Cuiper L. L. , Haselton F. R.
Published: December 2017

We previously reported that platelets release a soluble factor that decreases the solute permeability of cultured bovine aortic endothelial monolayers. This factor was characterized as heat stable, trypsin sensitive, and not serotonin, adenosine, ADP, or ATP [F. R. Haselton and J. S. Alexander. Am. J. Physiol. 263 ( Lung Cell Mol. Physiol. 7): L670–L678, 1992]. We now report its identity as lysophosphatidic acid (LPA). Endothelial permeability decreases rapidly, reversibly, and repeatedly when exposed to platelet supernatants. Continuous exposure produces a sustained decrease in permeability. Methanol extracts of platelet supernatants also decrease endothelial permeability. Treatment of methanol extracts of platelet supernatants with phospholipase B or alkaline phosphatase, which modify the structure of LPA, abolishes the permeability-decreasing activity. However, activity is unaffected by treatment with phospholipase A2. This pattern of enzyme inactivation is consistent with the structure of LPA. Furthermore, synthetic 1-oleoyl-LPA rapidly and significantly decreases endothelial permeability in a concentration-dependent manner. Platelet activation does not appear to be required to produce activity in supernatants from platelet isolations, since P-selectin expression is not increased and thromboxane B2is <14 pg/6,000 platelets. Our data show that platelets release a methanol-extractable compound with an enzyme degradation profile consistent with LPA, which decreases the permeability of endothelial monolayers in vitro. In vivo, LPA derived from platelets may be an important mediator of the transport barrier formed by the vascular endothelium.
Bradykinin BK2 receptors contribute to reflex cardiovascular responses during brief abdominal ischemia
Authors: Chahal Premjit S. , Rendig Stephen V. , Longhurst John C.
Published: December 2017

Ischemically sensitive visceral sympathetic nerve fibers, which are thought to represent the afferent limb of a strong cardiovascular pressor reflex, can be stimulated by exogenously applied bradykinin (BK). During ischemia, BK also is known to be produced locally and to serve as an endogenous stimulus for activation of ischemically sensitive nerve endings. It is unclear, however, whether ischemically induced BK production is sufficient to elicit a reflex cardiovascular response. Accordingly, femoral arterial and venous catheters were positioned in anesthetized cats, and the superior mesenteric and celiac arteries were isolated for placement of snare occluders. After dual occlusion of these arteries (20 min), one of two chemically dissimilar specific kinin B2(BK2) receptor antagonists, HOE-140 (30–40 μg/kg iv, n = 8) or NPC-17731 (30–40 μg/kg iv, n= 11), was administered and dual occlusion was repeated. The reflex rise of mean arterial blood pressure (BP) of 16 ± 3.7% was significantly ( P < 0.05) reduced by HOE-140 to 8.4 ± 2.0%. NPC-17731 similarly attenuated the reflex BP increment from 13 ± 1.2 to 6.2 ± 1.6% ( P < 0.05). In a separate set of control animals the first and second periods of ischemia induced reflex BP increments that did not differ significantly (16 ± 2.7 and 16 ± 5.7%, respectively). Qualitatively similar decrements of the BP response were produced by the BK2 receptor antagonists in two additional groups in which blood flow to the superior mesenteric and celiac arteries was diverted to a venous reservoir to eliminate the initial transient (mechanically induced) rise in BP associated with artery ligation that is known not to be associated with the reflex response. These results indicate that the stimulation of BK2 receptors on visceral afferent nerves by BK is responsible, at least in part, for the reflex cardiovascular response during visceral ischemia.
Growth and Fat Deposition in the Mouse
Authors: Fenton Paul F.
Published: December 2017

Mice of the C57BL/Fn strain and the I/Fn strain were placed after weaning on a diet containing 50% fat. The carcass fat content of C57BL/Fn mice increased linearly with the age of the animals. Plotting fat content against fat-free weight for young animals of the C57BL/Fn and all animals of the I/Fn strains yielded a straight line of slope 0.1. The data for older C57 animals (3–5 months) did not fall on this line. Obesity is defined in terms of the regression of fat content on fat-free weight.
Oxygen Consumption of the Breathing Processes
Authors: Ramos J. García , Arjona P.
Published: December 2017

In Nembutal-anesthetized rabbits, oxygen consumption of the entire animals was determined by means of a metabolism apparatus, and its variations with different degrees of breathing activities were studied. Breathing activity was varied either via the Hering-Breuer reflex, or by using different depths of anesthesia, or by changes in the dead space or resistance to air flow. Measurement of breathing activity was made by mechanical or electrical integration of the electromyograms of the diaphragm. Oxygen consumption has a linear relation with breathing activity. That relation can be modified by changes in heart rate, by asphyxia or hyperventilation, by the degree of activity of the sympatho-adrenal system or by too much Nembutal. Once these factors were controlled was found that oxygen consumption depends more on the integrated muscle activity than on either ventilation or breathing rate. It is emphasized that in some conditions the amount of oxygen used by the breathing processes can become an important fraction of the total basal metabolism.
Metabolism of Endogenous Lipid of the Intestine
Authors: Kim Kwang S. , Bollman Jesse L. , Grindlay John H.
Published: December 2017

Total fatty-acid output in the intestinal lymph in rats and in the thoracic-duct lymph in dogs was studied during fasting and during a fat-free diet period. Daily total fatty-acid output in the intestinal lymph was found to be fairly constant during fasting or when the rat was fed a fat-free diet. There is an inverse relationship between total fatty-acid concentration and the volume of intestinal lymph. In the absence of pancreatic juice or of both bile and pancreatic juice, the total fatty-acid output in the thoracic-duct lymph in dogs was decreased to one-third or one-fourth that of the normal dog. The endogenous lipid metabolism of the intestine is discussed in relation to steatorrhea.
Measurements of pH, Chloride and Inulin Concentrations in Proximal Tubule Fluid of Necturus
Authors: Giebisch Gerhard
Published: December 2017

To investigate the relationship between chloride concentration and acidification in the proximal tubule of Necturus simultaneous measurements of chloride, inulin and ph were carried out on samples of fluid obtained by micropuncture. The concentration of inulin in tubule fluid always exceeded that of serum, indicating reabsorption of fluid from this part of the nephron. The concentration of chloride in tubule fluid when treated with deproteinizing agents was found to be not significantly higher than that of the serum. The results of ph-measurements indicate that the proximal tubule in Necturus does not participate in urinary acidification, and no evidence of preferential reabsorption of bicarbonate could be demonstrated. The results resolve some discrepancies of earlier micropuncture studies and are in good agreement with known data on osmotic pressure and sodium concentrations in proximal tubule fluid of Necturus.
Renal Elimination of 3-Methylaminoisocamphane Hydrochloride (Mecamylamine)
Authors: Baer John E. , Paulson Sue F. , Russo Horace F. , Beyer Karl H.
Published: December 2017

Mecamylamine, 3-methylaminoisocamphane hydrochloride, a secondary amine with a pka of 11.4, can be both actively secreted and actively reabsorbed by the renal tubules in the dog. Net secretion occurs when the urine is acid; net reabsorption occurs when the urine is alkaline. A direct renal extraction study showed that tubular secretion occurred at rates equal to effective renal plasma flow. No self-depression of tubular secretion was observed at increased loads. The clearance of mecamylamine was depressed below glomerular filtration rate when the urine became alkaline, whether or not a systemic alkalosis existed. In some experiments, the clearance was as low as 3 ml/min., corresponding to reabsorption of more than 90% of the filtered drug. The secretory mechanism is not identical with that for p-aminohippurate. Approximately one-fourth of an administered dose of mecamylamine is excreted in the urine within 24 hours, whether the drug is given orally or parenterally. These data are consistent with the biological evidence that absorption from the gastrointestinal tract is essentially complete, and that extrarenal factors are important in the over-all physiological economy of the drug.
Effects of Pyruvate and Krebs' Cycle Intermediates on Hepatic Acetate Metabolism in Relation to Cold Exposure and Fasting
Authors: Masoro E. J. , Panagos Sylvia S. , Cohen Arthur I. , Rapport David
Published: December 2017

Liver slices were prepared from ‘control’ rats kept at 25°C, from fed and fasted rats kept at 0–2°C for 1 day, and from rats kept at 25°C without food for 1 day. The slices were incubated with sodium acetate-C14 at 37.5°C. The incorporation of the acetate-C14 into CO2, fatty acids and cholesterol was measured. The depressed acetate oxidation found in liver slices from ‘cold-fasted’ rats was reversed by the addition of glucose, pyruvate, or succinate to the incubation medium, the first two with equal effectiveness, the succinate less so. The fact that a certain minimum level of carbohydrate metabolism is needed to support hepatic acetate oxidation appears to be a function of the extent of pyruvate metabolism. Pyruvate stimulates hepatic lipogenesis from acetate to a much less extent than does glucose, while succinate has no effect at all on this process. The data indicate that the effect of carbohydrate metabolism on acetate lipogenesis is a function of processes occurring before the formation of pyruvate. Cholesterogenesis was for the most part unaffected by the substrates studied, and when an effect occurred, it could very well have been a function of isotope dilution.
Effect of Autoperfusion of the Liver on Detoxication of Thiopental Sodium
Authors: Rappaport A. M. , Hiraki G. Y. , Rosenfeld B. , Cowan C. R. , Lang J.
Published: December 2017

A decrease in hepatic circulation in dogs causes a significant delay in the detoxication of thiopental sodium. A method has been devised for arterial or venous autoperfusion of the liver with blood from the dog's own vascular system through an extracorporeal circuit driven by a pump with positive action valves. This produces an increase in flow even in damaged livers. In normal dogs the fall of plasma levels of thiopental is accelerated by autoprefusion of the liver. In Eck fistula dogs the retarded detoxication of thiopental became normal again after arterial autoperfusion. In Eck fistula dogs with subsequent (30 hr.) ligation of the common hepatic artery, the decreased rate of detoxication of thiopental is restored to normal by arterial or venous autoperfusion of the liver 18 hours after the ligation. The rate of detoxication of thiopental sodium depends not only on the state of the hepatic parenchyma, but also, to a surprising degree, on the amount of blood flowing through the liver. The clinical use of hepatic arterial autoperfusion is suggested in severe thiopental sodium (Pentothal) poisoning not responding to the usual therapy.
Influence of Temperature Stress on Uptake of P32 in the Rat
Authors: Sealander John A.
Published: December 2017

Different groups of rats were individually exposed to cold (2° ± 1.5°C) and hot (35° ± 1.5°C) environments for periods of 10, 23 and 29 or 30 days. After each period of exposure to either heat or cold a group of rats was dosed with tracer phosphorus, each rat receiving an intraperitoneal injection of about 20 µc P32. The rats were returned to the hot or cold environments and were killed after 48 hours. Five control rats were treated similarly but were kept at ordinary room temperatures. Measurements of P32 and total P on liver, bone, paired adrenals, brown fat and body fat showed that the percentage of the injected dose was significantly higher in heat-stressed as compared with cold-stressed rats in liver, bone and adrenal tissue. The percentage of injected dose in brown fat was significantly higher in cold-stressed rats than in heat-stressed rats. No significant differences were apparent for body fat. Observed differences in relative specific activity in different tissues from heat- and cold-stressed rats were interpreted primarily on a dilution basis. Evidence of acclimation to heat and cold after exposure periods of 29–30 days was provided by the reappearance of visible fat depots, recovery of body weight and adrenal weight changes. These findings suggest that the thermal environment of the animal must be carefully considered in any interpretation of tracer isotope studies concerned with metabolic processes.
Electroretinal Demonstration of a Purkinje Shift in the Chicken Eye
Authors: Armington John C. , Thiede Frederick C.
Published: December 2017

Spectral sensitivity of the chicken electroretinogram was determined for the photopic and scotopic condition. Physiological procedures were adopted which permitted the examination of the same three experimental animals upon repeated experimental occasions. It was found that this ERG exhibits components which are typical of the eyes of other animals, and a Purkinje shift could be demonstrated. Photopic ERG sensitivity agreed with the absorption spectrum of iodopsin. The form of the scotopic sensitivity curve suggested a mixed response in which the visual purple of the rods dominated, but in which a small contribution was made by the photopic iodopsin system.
Restoration of Chronotropic Effects of Vagus Stimulation on Isolated Perfused Heart of the Guinea Pig
Authors: Lynch Peter R. , Essex Hiram E.
Published: December 2017

As a result of observations on 50 isolated perfused hearts of guinea pigs it was found that the vagus nerves were active in 48 instances and the average duration of response to stimulation was 108 minutes. In one heart the vagi remained responsive to stimulation for 6 hours. It has again been shown that injections of appropriate doses of l-epinephrine are capable of restoring the unresponsive or exhausted vagal nerves to renewed chronotropic effectiveness.
Effect of Total Body Irradiation on Absorption of Sugars From the Small Intestine
Authors: Farrar John T. , Small Melvin D. , Bullard Doris , Ingelfinger Franz J.
Published: December 2017

A study was made in rats on the effect of large doses of total body x-irradiation on the intestinal absorption of glucose, fructose and xylose administered intraduodenally. Irradiation caused a slight but highly significant decrease in absorption of all three sugars when given singly. These studies do not indicate selective inhibition of any specific mechanism involved in the absorption of these three sugars. No difference attributable to sex exists between the postirradiation absorption rates. When mixtures of the three sugars were given, a questionably significant decrease was noted in all absorption rates, with the exception of xylose in the female rats. In this group absorption of xylose was unaffected by irradiation. In rats not exposed to irradiation, the relative absorption rates of the three sugars are markedly different when given singly and when given in a mixture.
Work Performance of Tumor-Bearing Rats
Authors: Ingle Dwight J.
Published: December 2017

Rats bearing Walker carcinoma 256 work much less than normal rats. The decrement in work is related to the size of the tumor and is greater for subcutaneous than for intramuscular tumors.
Carbohydrate Metabolism of Hypophysectomized Dogs as Studied With Radioactive Glucose
Authors: Steele R. , Wall J. S. , de Bodo R. C. , Altszuler N.
Published: December 2017

Minute amounts of uniformly labeled C14 glucose were administered intravenously to unanesthetized normal and hypophysectomized dogs, in the postabsorptive state, as an initial priming injection, followed by a constant infusion. From the observed specific activity of the plasma glucose during the 60–180-minute period of the constant infusion, the following parameters of carbohydrate metabolism were determined: a) the size of the glucose pool, b) the glucose space and c) the rate of turnover of the glucose pool. The rate of total CO2 production was also determined. The rate of total CO2 production, per square meter of body surface area, was found to be less in the hypophysectomized dog than in the normal one. The glucose pool, per kilogram body weight, was found to be smaller in the hypophysectomized dog than in the normal one. The glucose space, expressed as percentage of body weight, was found to be similar in the two types of animals. The rate of turnover of the glucose pool in the hypophysectomized dog, presented as grams glucose per square meter of body surface area per hour, was found to be less in the hypophysectomized dog than in the normal one. The low rate of glucose uptake by the tissues which was observed to prevail in the hypophysectomized dog is believed to reflect an adjustment in the secretion of insulin to conform to the limited availability of endogenous glucose which results from the removal of the pituitary gland.
Changes in Arterial Dilution Curves Associated With Blockage of Abdominal Aorta, Hypoxia and Hemorrhage
Authors: Ring Gordon C. , Moss W. Glen , Reiner I. , Partin H. , Kurbatov T.
Published: December 2017

The dye T-1824 and red cells marked with P32 were injected into the pulmonary artery of dogs. The characteristics of arterial dilution curves after blocking the descending aorta, after hypoxia and after transfusion following hemorrhage were studied. After pulmonary pressure was raised by blocking the aorta, the figure for peak concentration time divided by appearance time (PTC/AT) was increased, the concentration of labels rose to three-fourths of peak concentration more quickly and the figure for peak concentration divided by mean concentration (PC/MC) diminished. The results following hypoxia were variable. In only one out of eight dogs studied were the changes similar to those described above. In five opposite changes were found and in two the changes were mixed. Transfusion following hemorrhage resulted in changes which showed no regular pattern. The changes with blocking of aorta are those which we would predict if pulmonary shunts open. Those with hypoxia indicate that the opposite changes have occurred.
Transmembranal Action Potentials From Pregnant Uterus
Authors: Woodbury J. Walter , McIntyre Donald M.
Published: December 2017

For the first time overshooting action potentials of pregnant guinea pig uterus have been recorded intracellularly. Flexibly mounted ultramicroelectrodes were used. The largest action potential (AP) seen was 48 mv with an associated resting potential (RP) of 38 mv. The mean of 129 measurements of RP in four guinea pigs was 32.6 mv. The mean of 86 AP's was 21.9 mv. Although overshoot was seen only occasionally, the action potentials were always of the same order of magnitude as the resting potentials. It seems probable that the excitable mechanisms of uterine muscle though labile and variable are closely similar to those of other tissues.
Failure of Large Doses of Desoxycorticosterone Acetate to Block Mercurial Natriuresis in Adrenalectomized Dogs With Thoracic Inferior Vena Cava Constriction and Ascites
Authors: Goodkind M. Jay , Hyatt Robert E. , Davis James O.
Published: December 2017

Mercurial diuresis was studied in three bilaterally adrenalectomized dogs with thoracic inferior vena cava constriction and ascites. The effect of large doses of DCA (25 mg/day) on the natriuresis produced by mercury was determined. Large doses of DCA did not block the increased sodium excretion caused by Mercuhydrin in two of the three dogs. These findings are not consistent with the hypothesis that mercurial unresponsiveness results from increased amounts of circulating adrenocortical salt-retaining hormone.
Water Losses and Gains in Fasting and Nephrectomized Rats
Authors: Aach R. D. , Rolf D. , White H. L.
Published: December 2017

Fasting rats lose solids as fast as or faster than they lose water. After nephrectomy they gain water while losing solids. Calculated insensible water loss agrees with directly determined. Fall in plasma Na 24 hours after nephrectomy is accounted for by dilution effects (water gain plus exchanges with gastrointestinal contents, GIC), but fall in plasma Cl is greater, indicating cell entry of Cl. After 48 hours some cell entry of Na is indicated, with greater entry of Cl. A 1-kg normal nonfasted rat gains 705 – 678 = 27 gm water in 24 hours after nephrectomy. Of this retained water, 6 gm is in skin, none in liver or GIC, and 21 in remainder of carcass, largely in skeletal muscle. There is no change in grams water per kilogram fresh tissue after fasting or nephrectomy in heart ventricles or cerebral hemispheres, but there are significant increases in skin, muscle and liver, greater in nephrectomized than in fasting.
Utilization of Oxygen by Normal and Trauma-Resistant Rats Following Trauma and Exposure to Hypoxia
Authors: Manning John W. , Hampton John K.
Published: December 2017

No difference could be demonstrated between resting oxygen consumption of trauma-resistant and control rats, or their oxygen consumption at various levels of hypoxia. No difference could be demonstrated in the mean death time of trauma-resistant and control rats when subjected to low environmental oxygen tension. It was shown that the trauma-resistant rats were able to accelerate oxygen consumption following an amount of trauma which was sufficient to cause about 50% mortality and a decreased O2 utilization in control rats. It was not possible to predict from the immediate Qo2 following trauma whether a control rat in shock would survive or die. The data show that the trauma-resistant state is not characterized by an ability of the animal to tolerate cellular hypoxia or ischemia. The data are used to propose that the trauma-resistant state is characterized by a vascular system which maintains its integrity following trauma.
Pulmonary Reflexes in Pulmonary Edema?
Authors: Aravanis C. , Libretti A. , Jona E. , Polli J. F. , Liu C. K. , Luisada A. A.
Published: December 2017

The mechanism of pulmonary edema caused by stimulation of the central nervous system was studied in 33 dogs. Stimulation was obtained by the intracisternal injection of veratrine, or of air or saline under high pressure, or by electric stimulation of the hypothalamus. Pressure changes in the pulmonary artery, left atrium and left ventricle were recorded by means of three catheters introduced through the right external jugular vein and the left femoral artery. Experiments were performed with closed or open chest, and following ligation of the thoracic aorta and inferior cava. Lung opacity was studied as a means to estimate the blood content of this organ. Data obtained in closed-chest experiments suggest that a blood shift from the systemic to the pulmonary circulation may be a factor in veratrine-induced pulmonary edema. This was confirmed by the observation that, following mechanical exclusion of the systemic circulation, no pulmonary edema occurred while the changes of left ventricular pressure were minimal and inconstant. In these animals, pulmonary artery pressure still rose indicating vasoconstriction while an increase of lung opacity suggested that the vasoconstriction was greater in the pulmonary veins than in the arteries. Injection of air or saline under high pressure into the cisterna magna and faradic stimulation of the hypothalamus caused pulmonary hypertension, even after exclusion of the systemic circulation. In these experiments, a decreased lung opacity suggested that the pulmonary constriction was greater on the arterial than on the venous side. These findings are offered as evidence that the caliber of the pulmonary vessels may be influenced by central nervous system stimulation, an additional element to be considered in the mechanism of pulmonary edema.
Sphingosine as Inhibitor of Prothrombin Activation With Thromboplastin or With Threone
Authors: Hecht E. , Landaburu Ricardo H. , Seegers Walter H.
Published: December 2017

The activation of purified prothrombin with calcium ions, Ac-globulin and lung extract thromboplastin is inhibited with sphingosine prepared from natural sources and also with synthetic dl-sphingosine. Likewise, the conversion of purified prothrombin to thrombin with calcium ions, Ac-globulin and threone is inhibited; however, in low concentration sphingosine tends to accelerate thrombin formation. By definition threone consists of platelet factor 3 and platelet cofactor I. Either of these two substances, as purified concentrates, can overcome the inhibitory effect of sphingosine when added in large amounts.
Direct Effect of Corticotropin (ACTH) on Capillary Permeability in Inflammation
Authors: Menkin Valy
Published: December 2017

A series of experiments are described which indicates that corticotropin directly suppresses the increased capillary permeability at the site of inflammation without necessitating the mediation of the adrenals. The increased capillary permeability in an acutely inflamed area is referable to the liberation by the injured cells of two chemical factors: leukotaxine, repressed by cortisone, primarily liberated in the incipient alkaline stage; and exudin, repressed by corticotropin, chiefly released at a later or acid stage of the inflammatory reaction. The direct daily injections of corticotropin into an inflamed area at an acid ph in a dog, yields an exudate which progressively becomes incapable of increasing capillary permeability in the skin of a rabbit, as gauged by the local accumulation of trypan blue from the circulation. A similar picture is encountered when exudin is extracted from such samples of acid exudate. The capacity of exudin to induce increased capillary permeability is also gradually diminished following direct daily injections of corticotropin into the area of pleural inflammation. In adrenalectomized rats, exudin combined with corticotropin is likewise unable to induce an increased capillary permeability, in contrast to the normal accumulation of the dye in a skin area treated only with exudin. Furthermore, the direct effect of ACTH on capillary permeability in inflammation is not referable to an impurity in commercial ACTH, for similar suppressing effects are obtained with the use of the hormone in pure form, namely alpha-corticotropin.
Distribution of Infused Estrone in Human Plasma
Authors: Antoniades H. N. , McArthur J. W. , Pennell R. B. , Ingersoll F. M. , Ulfelder H. , Oncley J. L.
Published: December 2017

Intravenous infusions of 100 mg of estrone sulfate and of crystalline estrone were administered to adult male volunteers. Phlebotomy followed 2 hours after estrogen administration, 500 ml of whole blood being collected in each instance through a cationic exchange resin (Dowex-50). The plasma from each volunteer was fractionated immediately using Cohn's cold ethanol methods 6 and 9. The fractions obtained were I, III-0, II+IIIw, IV-1, IV-4, V and VI. Specific techniques were employed for the separation of the ß-lipoproteins and the albumin from fractions III-0 and IV-1. Estrogenic activity was assayed biologically in spayed rats by a modification of the method of Bulbring and Burn. Following the injection both of estrone sulfate and of crystalline estrone, the estrogenic activity was found associated with both the albumin and the α-globulins of the plasma. Fraction VI (albumin supernatant) exhibited activity in all experiments, due probably to the presence of unbound estrogens.
Vascular Changes in the Cheek Pouch of Adrenalectomized, Cortisone-Sustained and Cortisone-Treated Hamsters as Determined by Electrical Impedance Plethysmography
Authors: Liebman Frederick M.
Published: December 2017

The relationship of the adrenal corticosteroids to vascular function in the cheek pouch vessels of the hamster was studied by electrical impedance plethysmography, adapted to the study of vascular changes in a membranous structure, and enabling the detection of minute variations in volume. Adrenal corticosteroids are related to the arteriolar tone, and seem to be especially concerned with the state of the capillaries. In adrenalectomized animals the magnitude and direction of the volume change when compared to the controls, to cortisone-treated animals, and to cortisone sustained adrenalectomized animals, could be explained only on the basis of changes in the capillary wall which permitted the loss of protein and fluid from the capillaries.
Serum Potassium Concentration and Use of Ouabain in Experimental Tourniquet Shock
Authors: Rosse W. F. , Bennett A. L. , McIntyre A. R.
Published: December 2017

Shock was induced in dogs by the release of tourniquets which had been applied to the hind legs for 5 hours. The serum potassium level was followed by spaced sampling. It was seen to rise slightly (from an average of 4.02 mEq/l. to an average of 4.66 mEq/l.) during the prerelease period. Five minutes after the release of the tourniquets, the level had risen to an average of 7.50 mEq/l. and thirty minutes after the release, it had risen to an average of 8.56 mEq/l. At the critical point in the progress of the syndrome (when the mean blood pressure was approximately 50 mm Hg) the average value was 8.46 mEq/l. Ouabain was administered and the level of serum potassium was seen to rise, attaining values as high as 14.67 mEq/l. in one case. The results and significance of these increased levels are briefly discussed as well as an animadversion upon the effects of ouabain on the mean blood pressure.
Reflectance Spectra and Some Respiratory Reactions of Bovine, Equine and Human Thrombocytes
Authors: Goucher Charles R. , Kocholaty W.
Published: December 2017

Page 418: Charles R. Goucher and W. Kocholaty, "Reflectance Spectra and Some Respiratory Reactions of Bovine, Equine and Human Thrombocytes." By omission of the authors, figure 5 was not included. On this page, line 2 from the top should read "figure 5" instead of 4. The missing figure 5 is represented below.
Role of Pancreatic Digestion in Cholesterol Absorption
Authors: Lin T. M. , Karvinen Esko , Ivy A. C.
Published: December 2017

The exclusion of pancreatic juice had no significant effect on elimination of endogenous cholesterol in the rat but increased it slightly in three dogs. Forty per cent of the dietary cholesterol was absorbed without and with pancreatic exclusion in the presence of a fat-free diet. Hence, pancreatic juice is not specifically necessary for the absorption of cholesterol. Pancreatic exclusion had no effect on the absorption of either dietary cholesterol or fatty acid, or both, when oleic and palmitic acid were fed. This indicates that any effect pancreatic exclusion may exert on cholesterol absorption when a fat containing diet is fed depends on the change in the utilization of the fat resulting from the exclusion. In the case of corn oil, triolein, trielaidin and tallow but not with tripalmitin, pancreatic exclusion was followed by an increased fecal elimination of both fatty acid and cholesterol. The increment of fatty acid elimination was large enough to dissolve the excess cholesterol excreted in the rats with pancreatic exclusion, except in the case of trielaidin. The only statistically significant decrease in the absorption of dietary cholesterol which resulted from pancreatic exclusion occurred when one of the unsaturated fatty acid esters, namely, corn oil, triolein, or trielaidin was the fat fed. These observations fail to show that pancreatic cholesterol esterase plays a specifically essential role in the absorption of free dietary cholesterol.
Stimulation of Respiration and Secretion of Mouse Pancreas in Vitro
Authors: Dickman Sherman R. , Morrill Gene A.
Published: December 2017

Mouse pancreas has been incubated in vitro with the parasympathomimetic drugs pilocarpine and Carbachol and with the hormones pancreozymin and secretin. The first three substances stimulated both respiratory rate and rate of enzyme secretion whereas secretin stimulated only the respiratory rate. The time-course of stimulation by pancreozymin was followed. Its effect on the respiratory rate was immediate while the largest secretion of ribonuclease occurred after 30 minutes of incubation. The secretory and respiratory effects of pancreozymin were not decreased by atropine but were slightly lessened by banthine. Large differences were found in the nonstimulated extrusion of ribonuclease in different strains of mice.
Effect of Hypothalamic Lesions on the Responses to Cold and Immobilization in the Monkey
Authors: Poirier L. J. , Cordeau J. P.
Published: December 2017

Monkeys with bilateral lesions in the rostral hypothalamus show a loss of the hyperglycemic response to immobilization but retain normal eosinopenic and lymphopenic reactions and granulocytosis. Monkeys with bilateral caudal lesions involving the medial and lateral structures show when immobilized, a complete loss of the hyperglycemic response, depressed eosinopenic and lymphopenic reactions and a normal granulocytosis. With lesions involving only the more medial structures of the premammillary area, the hyperglycemic response to immobilization is intact, and the blood cells reactions identical to that of the preceding group. These results suggest that the rostral hypothalamus belongs to a nervous circuit originating in the rhinencephalic structures and whose function is to activate epinephrine release from the suprarenal medulla during emotional reactions.