bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Angiotensin on Noradrenaline-3H Accumulation and Synthesis In Vivo
Authors: Palaić Djuro
Published: April 2011

The effect of slow intravenous infusion of angiotensin (0.017, 0.17, and 1.7 μg/min/100 g) on the endogenous noradrenaline (NA) level and on the accumulation and synthesis of NA-3H was studied in rat heart, spleen, and aorta. No significant changes in endogenous NA level were observed in rat aorta and heart after infusion of angiotensin for 1 h. In the spleen, only, a statistically significant lowering of NA was observed with 0.17 and 1.7 μg/min/100 g of angiotensin. The entry of NA-3H into nerve terminals was not affected by angiotensin, but the retention of the amine in a nonmetabolized state was significantly reduced. The angiotensin action varied from one organ to another, reflecting the differences in their capacity to accumulate and metabolize NA. Angiotensin potentiated the inhibitory effect of desmethylimipramine and ouabain on NA accumulation. The incorporation of tyrosine-3H into adrenergic nerves was not blocked by angiotensin infusion, while the amount of newly sythesized catecholamines-3H was significantly reduced. It is suggested that angiotensin modulates the exchange and retention of NA by adrenergic nerves, possibly through an ionic membrane mechanism.
Site of Action of Angiotensin and other Vasoconstrictors on the Kidney
Authors: Regoli D. , Gauthier R.
Published: April 2011

Angiotensin II, angiotensin I, adrenaline, or noradrenaline was infused in rabbit kidneys isolated and perfused with oxygenated Krebs solution. Adrenaline increased the perfusion pressure and slightly decreased the filtration fraction and the glomerular filtration rate. Angiotensins had similar effects on the perfusion pressure, but significantly increased filtration fraction and glomerular filtration rate.It is suggested that adrenaline acts on the afferent, while angiotensins II and I constrict the efferent, glomerular artery.
Plasma corticosterone, hemoglobin, creatinine and blood urea nitrogen levels, and urinary corticosteroid amounts in mice made hypothermic by exposure to −10 °C
Authors: Grad Bernard , Rafizadeh Firouz
Published: April 2011

The plasma corticosterone (PC) levels of mice adapted to 27–28 °C rose significantly when they were exposed to the cold at −10 °C until they became comatose, the increase being significantly less during a second similar exposure a week later. The PC elevations which occurred at −10 °C before the mice became comatose could be due in some degree to renal impairment, as indicated by increases in blood urea nitrogen and plasma creatinine levels during the first and second exposures, respectively. However, hemoconcentration as indicated by changes in the hemoglobin level could not account for the increase in the PC level. Mice that became comatose at −10 °C also had significantly elevated PC levels which were probably not primarily due to hemoconcentration or renal impairment. Mice recovering from coma in the warmth also had elevated PC levels for 6 h after the first exposure and for 1 day after the second one. At 1 and 7 days following exposure to the cold, the adrenal cortex no longer appeared to be hyperfunctional. Renal function appeared to have been impaired for 4 h following the first exposure and for at least 7 days after the second one. This impairment could account for the elevated PC levels and lower urinary corticosteroid amounts observed on the first day following the second exposure.
Changes in the Electrophoretic Patterns of Euglobulin Fractions Following Activation of the Fibrinolytic System by Exercise
Authors: McAlpine Valerie , Milojevic Susan , Monkhouse Frank C.
Published: April 2011

A study was made of changes in blood fibrinolytic activity in a group of young male university students following varying levels of exercise. The subjects were divided into two groups. Those partaking in regular athletic programs were classified as athletes and those not as nonathletes. There was an increased fibrinolytic activity with increased severity of exercise in all subjects. Several of the nonathletic group showed a much greater maximum effect than their athletic counterparts, and all nonathletes showed the effect at much lower levels of exercise. Increase in fibrinolytic activity correlated well with increase in pulse rate. When euglobulin fractions from the plasma samples were subjected to microzone electrophoresis, there was a band change in the region of the beta globulins in many of the samples following exercise. This band change is apparent only when fibrinogen is present in the euglobulins and appears to be due to fibrinogenolysis as a result of the activation of the fibrinolytic system. These band changes were observed when the specific activity was as little as 0.058 unit of plasmin per milligram protein. Our results show that electrophoretic pattern changes of euglobulin fractions is a relatively sensitive and rapid method for detecting activation of the fibrinolytic system.
Caloric Uptake and Cold Resistance in Cold-Acclimated Rats Fed Commercial Chow or Semipurified Diet
Authors: Deslauriers Roxanne , Zoami Joe , McCullough Roger S. , Héroux O.
Published: April 2011

Sprague–Dawley male rats fed Master Lab cubes (MLC) or a semipurified diet (T4F) were kept for periods of 1–2 weeks at six subsequent temperatures : 28 °C, 22 °C, 6 °C, 0 °C, −10 °C, and −20 °C. Caloric balance, growth, body temperature, and survival were measured. As previously observed under outdoor winter conditions, with constant laboratory conditions T4F diet was still found to be superior to MLC in allowing a greater degree of cold resistance. At temperatures below 0 °C, in spite of a lower gross energy uptake, T4F-fed rats maintained a faster growth and a higher body temperature than MLC-fed rats, which suggests a greater heat conservation in these animals. Failure of MLC-fed rats to raise their gross energy uptake at −10 °C to a higher level than at 0 °C, and death of most of these animals at −20 °C within the first 3 days strongly suggest a physical limitation in the quantity of high bulk MLC diet which can be consumed every day, hence a limitation in energy uptake increase. The ability of T4F-fed rats, on the other hand, to raise energy uptake in a continuous linear fashion as temperature is reduced, and their capacity to draw on energy reserves and to survive longer at −20 °C reflect greater metabolic potentials in this group than in MLC rats.
Uptake of Tritium-Labelled Testosterone by Rat Femur: Effect of Disuse and Age
Authors: Grant Michael A. , Lindsay Hugh A. , Thomas John A.
Published: April 2011

Male rats 1 or 2 months of age at the beginning of the experiment were used. In each animal one leg was immobilized and the contralateral leg was used as control. Immobilization was maintained for 1, 2, or 3 weeks in each age group. Uptake of 3H-testosterone was measured in both femurs of each animal. Uptake of tritiated hormone decreased with age. Immobilization increased hormone uptake. The effect of immobilization on uptake varied with age. Variation in hormone uptake is proposed as an explanation of previously observed reversal of the effect of testosterone upon osteopenia of disuse in rats in these same age groups.
The Distribution of Red Cells in the Spleen
Authors: Song S. H. , Groom A. C.
Published: April 2011

Kinetics of red cell washout, when isolated cat spleens are perfused with Ringer solution, show that the spleen corresponds to a three-compartment system. To determine whether or not there exist morphological counterparts to these compartments we examined microscopic sections from 16 spleens perfused by different volumes of Ringer solution. Red cells could be divided into three groups: (1) free cells in vascular channels and sinuses, (2) cells adhering to reticulum cells or sinus endothelium, and (3) cells in the cytoplasm of macrophages. When 50 ml were perfused no free cells were seen in vascular channels. After 600 ml few free cells remained in the sinuses. Thereafter the number of cells adhering to the sinus wall decreased gradually and cell counts agreed with predictions from the washout curve. We conclude that the compartments of our model (fast, intermediate, and slow) represent, respectively, free cells in vascular channels, free cells within sinuses, and cells adhering to sinus walls. The only cells trapped irreversibly are the very few found in the cytoplasm of macrophages. It is suggested that the slow compartment represents red cells in a pre-phagocytosed stage, e.g. aged cells, abnormal cells containing inclusion bodies, and possibly, reticulocytes in the process of maturation.
Effect of Ethanol on Entry of some Substances into the Brains of Rats
Authors: Leslie Crystal A. , Gottesfeld Zehava , Elliott K. A. C.
Published: April 2011

We have examined the effects of a subanesthetic dose of ethanol on the entry into the brains of rats of three 14C-labelled substances which are known to affect brain function. All substances were given intraperitoneally. When ethanol was given the concentration of pentobarbital in the brain reached and was maintained at a higher level than without ethanol. The barbiturate entered the brain and became distributed between plasma, red cells, and brain extremely rapidly in the presence or absence of ethanol. Administration of ethanol decreased the rate of breakdown of pentobarbital, so that higher levels of unchanged pentobarbital were maintained in blood, liver, and brain. Breakdown of the barbiturate occurred rapidly in liver but almost no radioactive breakdown products entered or were formed in the brain. Thiamine entered the brain sparingly but, after 60 min, the ratio of radioactivity per gram of brain to that per milliliter of plasma became considerably greater with ethanol than without. In the absence or presence of ethanol this ratio increased with time due to a rapid disappearance of radioactivity from the plasma while radioactivity in the brain tended to increase slightly. In the presence of ethanol the rate of disappearance from the plasma increased, presumably due to increased uptake and metabolism of thiamine by other tissues. Urinary excretion of radioactivity decreased. Injected γ-aminobutyric acid (GABA), entered the brain very sparingly and much of what entered was metabolized. Ethanol had no effect on the endogenous GABA concentration in the brain nor on the entry or metabolism of injected GABA.
Effect of Spironolactone and Ethylestrenol on Benzo(a)pyrene Hydroxylase (EC 1.14.1.1) and Other Chemical Constituents of Hepatic Microsomes
Authors: Solymoss B. , Toth S. , Varga S. , Werringloer J. , Zsigmond G.
Published: April 2011

In rats, spironolactone and ethylestrenol, like phenobarbital, enhance the NADPH-dependent hydroxylation of benzo(a)pyrene in the hepatic microsomal plus supernatant fraction and increase liver weight and microsomal phospholipid content as well as NADPH cytochrome c reductase and diaphorase activities, but only ethylestrenol and phenobarbital influence the microsomal protein content and cytochrome P-450 level.Neither spironolactone, ethylestrenol, nor phenobarbital affects NADH cytochrome c reductase and diaphorase activities, and only phenobarbital alters the cytochrome b5 level.These findings indicate that, while both the steroids and phenobarbital stimulate microsomal mixed-function oxidation, there are qualitative and quantitative differences between their action.
The Effect of Cardiac Pacing at High Rates on Plasma Enzyme Levels in the Anesthetized Dog
Authors: Bolter Christopher P. , Critz Jerry B.
Published: April 2011

In pentobarbital-anesthetized dogs, cardiac pacing by an intra-atrial electrode at 240 beats/min resulted in small but significant increases in the plasma activity of glutamic–oxalacetic transaminase, which returned to control values within 30 min. No change in plasma creatine phosphokinase was observed following pacing. Possible mechanisms responsible for the release of tissue enzyme during pacing include an increase in rate of deformation of, and an increase in substrate transport by, the cardiac muscle plasma membrane.
Na+–Li+ Exchange in Single Muscle Fibers of the Giant Barnacle
Authors: Allen R. D. , Hinke J. A. M.
Published: April 2011

The net efflux of Na+ was measured in single muscle fibers of the giant barnacle, Balanus nubilus, bathed in Li+-Ringer solution. These experiments indicate one-to-one exchange of Li+ for Na+. This exchange occurs in two phases: a rapid exchange fraction complete within 1 h, and a slow exchange incomplete after 8 h. Intracellular Na+ activity, (aNa)i, decreased more slowly than total fiber Na+ concentration after immersion of the fibers in Li+-Ringer. The implications of this result regarding intracellular Na+ compartmentalization are discussed.
Effect of a Low Bulk Diet on Water and Electrolyte Exchange in Rats Exposed to Cold
Authors: Fregly Melvin J.
Published: April 2011

Exposure of rats to air at 6 °C for 10 days increased both intake of a low bulk diet and urine output, but failed to affect water intake. A comparison of urine output with water intake revealed a greater urine output at a given water intake in cold-exposed than in control rats. This suggests a possible mechanism for the relative dehydration induced by cold exposure. Both fecal and urinary routes of sodium and potassium excretion were increased by cold exposure. Fecal excretions of both sodium and potassium were similar fractions of their total outputs prior to, as well as during, cold exposure. In addition, both sodium and potassium exchanges were unaltered by cold exposure. These results suggest that the greater fecal sodium and potassium excretions observed previously with a high bulk food are related to fecal bulk and not to cold exposure per se.A post-cold drinking response was observed at 1, 2, and 3 h after removal from cold and is consistent with maintenance on a low bulk diet.
Effect of α- and β-Adrenergic Stimulation on the Uterine Motility and Adenosine 3′,5′-Monophosphate Level
Authors: Polacek Ivo , Daniel Edwin E.
Published: April 2011

In experiments on isolated rat uteri the relation was studied between the mechanical effects of catecholamines and the level of adenosine 3′,5′-monophosphate (cAMP). Adrenaline (1–100 ng/ml) caused relaxation of isolated rat uteri and a highly significant increase in the tissue cAMP concentration; both relaxation and cAMP increase were blocked by propranolol or butoxamine but unaffected by phenoxybenzamine. The rise in cAMP level was maintained in a Ca-free solution when the muscle could not contract. The stimulation of α-receptors of propranolol-pretreated uteri induced contractions but it caused no change in the cAMP concentration. cAMP level, increased by a previous application of isoproterenol, remained unchanged when the uterus contracted after application of oxytocin, propranolol, or propranolol with adrenaline. cAMP levels remained elevated after previous adrenaline whether oxytocin dose–effect curves were still shifted to the right or were shifted back by subsequent propranolol. Adrenaline decreased significantly the ATP concentration in the uterus. The effect persisted with a propranolol blockade but was reversed to an increase by pretreatment with phenoxybenzamine or in a Ca-free solution. We conclude that the level of cAMP in the uterus is controlled by mechanisms related to β-receptors but that α-receptor mechanisms do not affect cAMP levels. Also the level of cAMP is not the primary determinant of uterine motility.
Streptozotocin-Induced Diabetes and Regulation of Hepatic Glucose Metabolism
Authors: Singhal R. L. , Parulekar M. R. , Ling G. M.
Published: April 2011

Three days after a single injection of streptozotocin (7.0 mg/100 g) rats showed hyperglycemia, depletion of liver glycogen, and changes in the activities of several important hepatic enzymes involved in the synthesis and utilization of glucose. The observed metabolic changes were completely reversed following administration of insulin. The insulin-induced rise in the activities of certain hepatic enzymes was inhibited by cycloheximide. The results suggest that streptozotocin can replace alloxan as a potent cytotoxic agent for pancreatic β-cells for investigating the metabolic derangement seen during diabetes.
Collagen Metabolism in Bone and Carrageenin Granuloma by Sulfate-Deprived and Sulfate-Supplemented Rats
Authors: Brown R. G. , Liddy Eileen P.
Published: April 2011

The influence of sulfate deprivation on the rate of (14C)-proline incorporation into (14C)-hydroxyproline of carrageenin granulomata and bones in rats was investigated. The sulfate-deprived rats incorporated (14C)-proline in hydroxyproline at a rate which was approximately twice that of their controls in both bones and granulomata. These results were subject to two interpretations. In the first, sulfate deprivation was visualized as resulting in an increased turnover rate in the short half-lived components of tissue collagen. A second and perhaps less probable explanation was that sulfate deprivation resulted in a change in the character of the short half-lived preforms of collagen present in the tissues studied.
Measurement of Cardiac Output in Rats by 125I Dilution
Authors: Cotton R. T. , Mugashe F. L. , Gallie B. L. , Chan H. , Koven I. H. , Drucker W. R.
Published: April 2011

A simple, rapid, indicator-dilution method of estimating cardiac output in small animals using 125I human serum albumin has been developed. The variation of repeat determinations in a single animal was ±10%. The cardiac output in normotensive 250–350 g Wistar male rats was 217 ± 28 (±S.D.) ml/kg min−1. These results agree with others derived by more tedious methods. After the mean arterial blood pressure was reduced to 50 mm Hg for 60 min by hemorrhage the cardiac output declined to 104 ± 40 ml/kg min−1. With this method it is possible to repeat determinations of cardiac output during shock.
Electroretinographic Determination of Spectral Sensitivity in Albino and Pigmented Brook Trout (Salvelinus fontinalis, Mitchill)
Authors: Kobayashi H. , Ali M. A.
Published: April 2011

A technique for recording electroretinograms from the unpunctured eyes in situ of living, anesthetized fish is described. This technique permits the use of the same fish in a number of experiments over a period of weeks, months, or years. Using this technique the spectral sensitivity of dark-adapted (scotopic) and light-adapted (photopic) fish was measured at 13 bands of the visible spectrum. The scotopic curves of albino and pigmented trout thus obtained in the winter have their maxima around 525 nm which differ from that of the absorption spectrum of the scotopic pigment in situ and in vitro of older fish obtained in the summer. The photopic curve of the pigmented fish is a broad one with humps around 425 nm, 545 nm, and 595 nm. The albino's curve has a relatively narrow band with a peak around 630 nm and a shoulder at about 550 nm. The difference between the shapes of the two curves may be ascribed to the increase in the intensity of light of longer wavelengths within the eyeball of the albino, due to reflection from blood vessels and sclera caused by the absence of pigmentation.
The Effects of Drugs on Limulus Cardioregulators
Authors: Burg R. Von , Corning W. C.
Published: April 2011

Previous lesion and stimulation research has demonstrated the existence of both cardioaccelerators and cardioinhibitors in Limulus abdominal ganglia. Perfusion of the ganglia with various drugs indicates that it is possible to selectively activate cardioaccelerators with acetylcholine or eserine and cardioinhibitors with picrotoxin. γ-Aminobutyric acid acts as a non-specific inhibitor of both functions.
The Effect of Oral Oxyphenbutazone (Tandearil) on Tumor Growth and the Level of the Seromucoid Fraction in Rats Bearing Walker 256 Carcinoma
Authors: Macbeth R. A. L. , Fischer J. D.
Published: April 2011

The effect of the oral administration of oxyphenbutazone (Tandearil) on tumor growth and the levels of the seromucoid protein and seromucoid-bound carbohydrates of rats bearing Walker 256 has been studied. Oxyphenbutazone was administered at two dose levels, namely 60 mg/kg per day and 100 mg/kg per day. The anticipated elevation of seromucoid protein and seromucoid-bound carbohydrates was observed in untreated tumor-bearing rats. Oxyphenbutazone treatment suppressed the initial response of seromucoid protein and seromucoid-bound carbohydrate in tumor-bearing rats such that no significant elevation occurred over levels recorded for untreated nontumor-bearing rats for the first 8 days following transplantation. After 8 days the levels of seromucoid protein and seromucoid-bound carbohydrate were elevated in treated tumor-bearing animals as compared with untreated nontumor-bearing controls although the magnitude of the elevation was significantly less than that observed in untreated tumor-bearing animals.Oxyphenbutazone at an oral dose of 100 mg/kg per day proved toxic to the adult male rat. Toxicity was manifested by weight loss and occasionally by a fatal hemorrhagic gastritis.Tumors regressed in oxyphenbutazone-treated animals, and survival times of animals treated with oxyphenbutazone at 60 mg/kg per day exceeded those of comparable untreated tumor-bearing animals. In addition, treated animals were free of apparent malignant disease at the completion of the study.
Physical Characteristics of Red Cells Collected from the Spleen
Authors: Groom A. C. , Song S. H. , Lim P. , Campling B.
Published: April 2011

Kinetics of cell washout, when isolated cat spleens are perfused with Ringer solution, have shown previously that the red cells stored in the spleen correspond to a system of three compartments (fast, intermediate, and slow); morphological studies, at different stages of the washout, have already identified these compartments as free cells in vascular channels, free cells within sinuses, and cells adhering to sinus walls, respectively. By collecting the venous outflow at three particular stages of the washout fairly pure samples (>85%) of the cells from each compartment have now been obtained. We have measured the density (phthalate method), volume, and osmotic changes (Celloscope) of these cells. Cells from the fast and intermediate compartments were not significantly different from those of arterial blood, but cells from the slow compartment were lighter (specific gravity difference was 0.0064; p < 0.01), larger in volume (5.0%; p < 0.01), and swelled 14% less in 200 mOsmol/l (p < 0.01). These differences indicated that cells from the slow compartment might be predominantly younger cells and this has been confirmed by finding reticulocyte counts of 58.0 ± 3.8 (S.E.) %. It is suggested that immature red cells, released from the bone marrow, may be sequestered in the spleen and matured.
Neck Muscle Proprioceptors and Vestibulospinal Outflow at Lumbosacral Levels
Authors: Abrahams V. C.
Published: April 2011

It has been shown that neck muscle proprioceptors can inhibit vestibulospinal outflow at lumbosacral levels of the cord. The inhibition was abolished by decerebration, but was unaffected by ablation of the contiguous regions of the ectosylvian and suprasylvian gyri receiving vestibular projections. Descending vestibular effects on segmental lumbosacral reflexes were also examined. One effect only, a prolonged facilitation of the monosynaptic reflex, was abolished by decerebration. Unlike a similar effect obtainable from neck muscle proprioceptors, the facilitation survived acute ablation of the anterior poles of the suprasylvian and ectosyivian gyri.
The Metabolism of 3H-Labelled Estrone by the Isolated Perfused Liver of the Rabbit, Chicken, and Guinea Pig
Authors: Quamme G. A. , Layne D. S. , Williamson D. G.
Published: April 2011

Isolated livers of rabbits, chickens, and guinea pigs were perfused with whole blood containing tritiated estrone in order to examine the metabolites of this estrogen formed by the liver and released into the blood. The major metabolite found in the blood was estradiol-3-glucuronide-17α-N-acetyl-glucosaminide in the rabbit although some monoglucuronide was formed. The monoglucuronides of estrone and 17β-estradiol were the major metabolites in the guinea pig. In the chicken the 17-monosulfate and the disuifate of 17β-estradiol were present in approximately equal quantities. Glucuronides were also identified. The estrogen metabolites formed by the perfused liver were similar to those found in the excretory products of the intact animals.
Evaporative Cooling in the Rat: Further Consideration of Functional Differences Between Salivary Glands
Authors: Hainsworth F. Reed , Stricker Edward M.
Published: April 2011

Previous reports indicated that submaxillary saliva, but not parotid saliva, was crucial to thermoregulation in the male rat exposed to inescapable heat stress, and emphasized the lower level of hyperthermia associated with the initiation of submaxillary secretion as one factor accounting for the difference between individual salivary glands. The present results indicated that submaxillary saliva was also crucial to the survival of female rats exposed to moderate heat stress, yet submaxillary and parotid secretions were increased at comparable levels of hyperthermia. Thus, it appears that the most important difference between the glands is not the level of hyperthermia associated with increased salivary secretion but the amount of fluid that is provided once secretion is begun.
Renin Release Stimulated by an Acute Increase in Hematocrit in the Dog
Authors: McDonald K. M. , Smith D. A.
Published: April 2011

The hematocrit was increased acutely in anesthetized dogs by means of an isovolemic exchange transfusion in which packed red cells from a donor dog were infused in exchange for an equivalent volume of whole blood. Renin release by the kidney increased three- to eightfold in response to a 20% rise in hematocrit. No increase in renin release occurred when the exchange transfusion was performed with reconstituted blood having the same hematocrit as the dog's own blood. The increase in hematocrit caused a decrease in p-aminohippurate clearance (77 to 48 ml/min) and sodium excretion (223 to 85 μequiv/min) but caused no change in mean arterial pressure or glomerular filtration rate. The results suggested that changes in the rheological properties of blood provide a potent stimulus for renin release by the kidney.
Alteration of Rat Brain Catecholamine Metabolism During Exposure to Hypobaric Hypoxia
Authors: Cymerman A. , Robinson S. M. , McCullough D.
Published: April 2011

The effect of hypobaric hypoxia on the metabolism of brain catecholamines in the rat was studied using intracisternal injections of 3H-tyrosine (3H-TYR) and 3H-dihydroxyphenylalanine (3H-DOPA) and intraperitoneal injections of α-methyltyrosine. Adult male Sprague–Dawley rats were housed singly or in pairs in barometric chambers and either maintained as controls or exposed to a hypoxic environment (380 mm Hg) for periods ranging up to 30 h. Whole brain norepinephrine (NE) and dopamine (DA) concentrations were significantly less than controls after exposures of 6, 12, and 18 h and normal after 24 h. Significant increases in specific activity of 3H-NE and 3H-DA derived from 3H-DOPA were obtained from brains of animals exposed for 6–18 h. The increase in 3H-NE specific activity was also evident with exposures lasting up to 30 h. Levels of 3H-NE derived from 3H-TYR were also increased with 12 h exposure when compared to controls. Turnover rates of NE, determined after pool size returned to normal (24 h), were not altered. Changes in cerebrospinal fluid composition, flow, and pressure may be responsible for the observed increases in 3H-NE derived from 3H-TYR or 3H-DOPA.
Ascorbate Metabolism in Swine. Influence of Maternal Hypoxia on Fetal Tissue Ascorbate Levels
Authors: Brown R. G. , Harris W. H. , Cummings J. N.
Published: April 2011

The effects of birth on tissue and serum ascorbate levels as well as the influence of maternal hypoxia on fetal tissue and serum ascorbate levels were investigated. Serum and adrenal ascorbate levels in neonatal swine were drastically decreased when compared with near-term (112-day-old) fetal swine. Kidney, cardiac, and muscle ascorbate levels also were found to be decreased on birth although liver levels in the newborn rose significantly above fetal levels. Hypoxic stress produced by decreasing the oxygen concentration in the maternal gas supply produced effects in 112-day-old fetal pigs which were similar to those noted for birth. An hypothesis was presented to explain the observation in which it was suggested that ascorbate may have a key role in the mechanism by which the fetal pig successfully coped with the stress of birth.
Nombres de Transport, tK, tNa et tca Pour la Membrane de la Cellule Hépatique In Vivo
Authors: Caillé Jean Pierre , Schanne O. F.
Published: April 2011

We measured the membrane potential of the liver cell in vivo at 38 °C as we increased the external potassium. For the range of K concentration from 20.4 to 78 mM, the membrane potential of the liver cell decreased with a slope of 20.2 mV per decade change in external K concentration. The tissue content of K, Na, and Cl was analyzed under the same experimental conditions. The cytoplasmic resistivity (111 ± 17.5 Ω-cm) was used as a criterion for the state of the ions in the cytoplasm. This result, when it is compared with the value predicted from the ionic content, suggests that either the ionic mobility or the ionic activity in the cytoplasm of the liver cell is less than in a simple salt solution. An analytical expression, derived with the use of irreversible thermodynamics, permits us to calculate the transport numbers for the ions K, Na, and Cl in the membrane of the liver cell (tK 0.28, tNa 0.12, tCl 0.61).
Effect of Vagotomy on the Renal Response to Blood Volume Expansion in the Rat
Authors: Veress A. T. , Pearce J. W.
Published: April 2011

Bilateral cervical vagotomy in the rat reduces the diuretic but not the natriuretic response to vascular expansion by infusion of whole blood. The attenuation of volume diuresis is similar to that observed in rats with intact vagus nerves but receiving an infusion of pitressin as well as the vascular expansion. The findings are consistent with the Gauer–Henry reflex, which attributes volume diuresis in part to reflex inhibition of vasopressin release, but imply that vagal afferents are not involved in volume natriuresis.
The Influence of Cations on Spontaneous and Chemically Induced Efflux of Noradrenaline from Perfused Rat Hearts
Authors: Nash C. W. , Taylor G. S. , Drouin T. E.
Published: April 2011

Isolated rat hearts perfused with Krebs bicarbonate solution and labelled with 3H-noradrenaline (3H-NA) were used to study the influence of various cations on the efflux of noradrenaline from sympathetic nerve endings. Evidence is presented that EDTA causes release by influencing Mg more than Ca ions, possibly those associated in a Mg–ATPase complex at the storage granule. Calcium is required for release by excess potassium but inhibits release caused by BaCl2. In contrast to sustained increases in the rate of 3H-NA efflux caused by EDTA and noradrenaline, potassium and barium ions initiate short-duration increases which subside while the initiating agent is still present. It is postulated that potassium and barium may cause 3H-NA release from a limited pool of granules adjacent to the membrane or may make available a limited supply of intracellular free Ca ions to initiate release at the storage granules.
Effects of Guanethidine and Related Compounds on Histamine Excretion
Authors: LeBlanc J. , Côté J. , Doré F. , Rousseau S.
Published: April 2011

The basic nature of guanethidine and some of its effects suggested a possible action of this drug on histamine metabolism. A single intraperitoneal injection of guanethidine (10 mg/kg) in male rats was found to double the daily urinary excretion of free histamine; daily injection for three weeks caused a 10-fold increase. In male rats, guanethidine increased the number of mast cells in the peritoneal fluid and, in both peritoneal fluid and mesentery, caused a significant degranulation of these cells; this action was not observed in female rats. This finding may indicate that guanethidine blocks methylation of histamine by inhibiting imidazole methyl transferase since this enzyme is found in male but not in female rats. Bethanidine and reserpine had no effect on histamine excretion. Imidazole was found to be even more potent than guanethidine in causing an increase in urinary histamine. Guanethidine and imidazole neither potentiated nor mimicked the action of histamine on the isolated ileum.
Relation Between Drug-Metabolizing Activity and Phospholipids in Hepatic Microsomes. I. Effects of Phenobarbital, Carbon Tetrachloride, and Actinomycin D
Authors: Cooper S. D. , Feuer G.
Published: April 2011

The treatment of rats with phenobarbital caused a significant increase in hepatic microsomal content of protein and phospholipid in parallel with the induction of drug-metabolizing enzymes. In contrast, carbon tetrachloride significantly reduced microsomal protein, phospholipid, and drug-metabolizing enzyme activity. The opposing actions of these compounds were manifested mainly in the phosphatidylethanolamine, phosphatidylcholine, and lysophosphatidylcholine fractions.Actinomycin D was found to block all the effects of phenobarbital except for the increase in lysophosphatidylcholine which was inhibited only by about 50%. Actinomycin D alone significantly decreased drug-metabolizing enzyme activity and microsomal phospholipid content.
Studies on the Sensitization to Cardiovascular Effects of Catecholamines
Authors: Vallières J. , Bureau M. , LeBlanc J.
Published: April 2011

Wistar rats were given 20 daily injections of either isoproterenol (ISO) (30 μg/100 g/day), nor-adrenaline (NA) (30 μg/100 g/day), guanethidine (G) (15 mg/kg/day), or NA plus G together. Guanethidine, alone or in association with NA, increased the blood pressure and heart rate response to NA in the whole animal. Guanethidine alone had no effect on the inotropic effects of NA in isolated hearts. Beta receptor responses to NA were potentiated in the whole animal by chronic treatment with NA and in isolated hearts by chronic treatment with NA or ISO. Responses to ISO were also potentiated by treatment with guanethidine, noradrenaline, and isoproterenol. It was found also that guanethidine treatment reduced 3H-NA uptake by 50% but had no effect on 3H-ISO uptake and that NA and ISO treatments had no effect on the uptake of 3H-NA and 3H-ISO. Prolonged treatments with NA or ISO increased the sensitivity of the beta receptors, possibly as a result of the repeated stimulations by large doses of these stimulants. The sensitization of adrenergic receptors by guanethidine could result from both a reduced NA uptake and a direct action on smooth muscle fibers.
In Vivo Release of Antidiuretic Hormone by Direct Application of Acetylcholine or Carbachol to the Rat Neurohypophysis
Authors: Gosbee J. L. , Lederis K.
Published: April 2011

A stereotaxic method is described for the in vivo study of neurohypophysial function in the rat. The infusion of nanogram quantities of acetylcholine or carbachol close to or directly into the neurohypophysis of water-loaded, ethanol-anesthetized rats resulted in a decreased urine volume and increased urine conductivity. These changes were matched by microunit quantities of Pitressin. It is concluded that acetylcholine may act directly on the neurohypophysis to modulate antidiuretic hormone release. The failure of earlier in vitro experiments to reveal this action may have been due to the high basal rate of hormone release in such experiments.
Effect of Sulfated Galactan from Hypnea japonica on Bone Metabolism in Rat
Authors: Hong K. C. , Cruess R. L. , Skoryna S. C.
Published: April 2011

Sulfated polysaccharide from Hypnea japonica and 45Ca was administered into growing rat by intubation or intravenous injection. 45Ca uptake and changes in the phospholipid, collagen, and mucopolysaccharide contents of the metaphyseal and diaphyseal bone were determined. The administration of the polysaccharide caused an increase in 45Ca uptake and in the content of phospholipid and hexosamine of the matrix with a diminution in the hydroxyproline content.
Observations on the Measurement and Regulation of the Sodium Content of Rabbit Erythrocytes: Evidence for a Single Sodium Pump
Authors: Smith E. K. M. , Farrington D. , Sydiuk L.
Published: April 2011

We have studied the cation content of rabbit erythrocytes; for a group of 40 animals red cell sodium was 9.2 ± 2.7 (S.D.) mmol/1 of cells, while potassium was 112 ± 8.6 mmol/1. Cell sodium content rose as the animals aged, but there was always a wide concentration gradient across the cell wall. This gradient was maintained by an active sodium pump, inhibited by ouabain (10−4 M) and comparable to pump I in the human red cell. The rate constant for this process in 16 rabbits was 0.313 ± 0.07 (S.D.) h−1, a value similar to that seen in man. Ethacrynic acid (10−3 M) inhibited a further component of sodium efflux, the rate constant being 0.259 ± 0.015 (S.D.) h−1. This was superficially comparable to pump II as previously described in the human; on further study, however, it was found to be sodium dependent, but able to function in the absence of adenosine triphosphate and incapable of net up-hill transport. These findings indicate that there is only one active transport mechanism in the red cells of the rabbit, which is a useful model for study in comparison to the red cells of man.
Ethoheptazine–Monoamine Oxidase Inhibitor Interaction in Rabbits
Authors: Sinclair John G.
Published: April 2011

Previous reports indicate that meperidine but not morphine produces a marked hyperpyrexia and death in monoamine oxidase inhibitor (MAOI) pretreated rabbits. Since this interaction may be predictive of a serious clinical drug–drug interaction, several other narcotic or structurally related agents were similarly tested in this study. Ethoheptazine citrate (10 mg/kg i.v.), whose chemical structure closely resembles that of meperidine, was found to produce extreme hyperpyrexia and death in rabbits pretreated with an MAOI, phenelzine sulfate (30 mg/kg i.p.), 42 and 18 h prior to temperature recording. This interaction appears to be due to an exaggerated 5-hydroxytryptamine effect. Of the other drugs tested, methadone was found to be inconsistent in its actions whereas anileridine alphaprodine, piminodine, dextropropoxyphene, levorphanol, levallorphan, codeine, and nalorphine were shown to be inactive.
Effects of Ethacrynic Acid on Vascular Resistance, Metabolism, and Electrolyte Flux in the Canine Gracilis Muscle
Authors: Ogilvje R. J. , Mikulic E.
Published: April 2011

The effects of intra-arterial ethacrynic acid (EA) on vascular resistance, metabolism, and electrolyte flux was studied in the isolated denervated canine gracilis muscle perfused with a constant inflow of arterial blood. Skeletal muscle vascular resistance was markedly reduced from baseline by 25-min infusions of EA producing blood concentrations of 10−3 M but not at concentrations of 10−5 M. There were no consistent alterations in the uptake of glucose, production of lactate, or flux of potassium in the gracilis muscle during the drug infusions or 45 min postinfusion period. Venous osmolality did not change. However, the arterio venous difference for oxygen saturation across this skeletal muscle was significantly reduced by EA treatment suggesting that oxygen utilization had been inhibited. Thus, EA has a direct vasodilatory effect which is independent of measurable changes in gracilis muscle electrolyte flux or metabolism other than a possible reduction in oxygen uptake or utilization by this muscle.
Effect of Glucagon on Glucose Turnover and Plasma Free Fatty Acids in Depancreatized Dogs Maintained on Matched Insulin Infusions
Authors: Cherrington A. , Vranic M. , Fono P. , Kovacevic N.
Published: April 2011

It has been shown previously that glucagon can increase the turnover of glucose in normal dogs and can enhance the secretion of insulin. The aim of this study was to determine the metabolic effects of glucagon independent of the effects of the insulin it releases directly through an action on β cells, and indirectly through hyperglycemia. Eight conscious dogs which could not mobilize extra insulin were obtained by replacing the endogenous insulin secretion of each with an equivalent intraportal infusion of the hormone immediately following removal of a remnant pancreatic autograft. Such infusions (200 μU/kg-min) maintained normal plasma concentrations of glucose and free fatty acids (FFA), as well as normal tracer-determined rates of glucose appearance (Ra) and disappearance (Rd) prior to glucagon infusion.There was a highly significant regression of the increments in glucose production on the rate of glucagon infusion (1.00–3.00 μg/kg-h). Rd increased proportionally to glucose levels, and there was therefore no significant change in the metabolic clearance of glucose. Hence a direct inhibitory effect of glucagon on glucose utilization could not be demonstrated. Corrections for recycling of the infused label did not appreciably affect the observed changes in Ra or Rd. Glucagon infusions did not increase the FFA level in plasma; when hyperglycemia was prominent a small decrease occurred. The role of glucagon in the net release of FFA from adipocytes in dogs is therefore questioned.
Cardiovascular Effects of Propranolol during Acute Experimental Anemia in Dogs
Authors: Chapler C. K. , Hatcher J. D. , Jennings D. B.
Published: April 2011

The effects of beta blockade on the cardiovascular responses observed 30 and 60 min following the production of anemia were investigated in anesthetized dogs. Comparisons were made between two groups of anemic animals, one of which was given propranolol prior to the production of anemia by rapid dextran-for-blood exchange. Pretreatment of anemic animals with propranolol did not affect the change in cardiac output [Formula: see text], stroke volume (VS), arterial oxygen transport [Formula: see text] or right ventricular end diastolic pressure PRVED 30 min following the exchange procedure. However, by 60 min the propranolol-treated group had a lower [Formula: see text] and [Formula: see text] and a higher PRVED than the untreated group. The similariiies between the two anemic groups at 30 min postexchange indicated that neither sympathetic beta blockade nor the direct myocardial depressant effects of propranolol abrogate the cardiac response to anemia at this time. The increase in PRVED in the propranolol-treated anemic series, 60 min postexchange, coupled with the failure of [Formula: see text] to increase between 30 and 60 min, as observed in the untreated anemic series, may suggest that the treated group was exhibiting early signs of reduced cardiac contractility.
Ambivalence in Rate Using Single-Lever Skinner Boxes
Authors: St-Laurent J. , Leclerc R. , Beaugrand J. , Mitchell M. , Paradis M.
Published: April 2011

Ambivalent behavior or ambivalence in rats was observed in a single-lever Skinner box situation. The behavioral features associated with ambivalence were filmed and described, and their intensities were graded. It was found that different behavioral patterns, depending on the site of stimulation, are involved in ambivalence. Moreover, the intensity of self-stimulation and withdrawal was found to be higher in subjects implanted in posterior brain areas than in rats implanted in anterior areas, suggesting the existence of a gradient of ambivalence. At a theoretical level, it was suggested that complex mechanisms, possibly involving an autonomous ambivalent system, could be responsible for ambivalence.
Similarity between Effects of General Anesthetics and Dinitrophenol on Cortical Neurones
Authors: Catchlove R. F. H. , Krnjević K. , Maretić Hermina
Published: April 2011

In lightly anesthetized cats, a brief administration of methohexital (intravenously), or halothane, methoxyflurane, or other gaseous anesthetics (by inhalation) causes a temporary, selective depression of the spontaneous firing and acetylcholine-evoked responses of deep pericruciate neurones, but relatively little change or even an enhancement of glutamate-evoked firing. These effects are very similar to those produced by local application of dinitrophenol, and therefore support the idea that anesthetics act by inhibiting aerobic metabolism.
Failure to Demonstrate Non-aldosterone Salt-Retaining Substances in Plasma, Urine, and Liver Extract of Chronic Caval Dogs
Authors: Mittelman Joseph , Levy Mortimer
Published: April 2011

The combined factors of depressed renal function and hyperaldosteronism by themselves do not adequately explain the progressive sodium retention of the chronic caval dog. The possibility that non-aldosterone salt-retaining humoral factors may play a major role in the sodium retention of this edema state has not previously been explored using bioassay techniques. In the present study we obtained ascitic fluid and plasmas from a variety of drainage areas from both control and caval dogs and infused them directly into the left renal artery of small dogs, pretreated with large doses of DOCA and undergoing a modest natriuresis. No decrement in sodium excretion was observed. When arterial plasma, hepatic venous plasma, ascitic fluid, urine, and saline extracts of liver were fractionated and concentrated up to 200 times, no evidence for a non-aldosterone antinatriuretic factor could be obtained in the bioassay system for fractions in the range 500 – 50 000 molecular weight. Within the limitations of the preparative and bioassay techniques used, we could therefore not obtain any evidence for the existence of non-aldosterone salt-retaining substances in the plasma, urine, or liver of chronic caval dogs.
The Effects of Chronic Unilateral Renal Artery Constriction on Blood Pressure, Separate Renal Function, and the Development of Collateral Circulation in the Dog
Authors: Zweig S. M. , Rapoport A. , Wilson D. R. , Ranking G. N. , Husdan H.
Published: April 2011

In 10 dogs in each of which one kidney was left intact, unilateral renal artery constriction (R.A.C.) resulted in an increase in aortic pressure (PA) for as long as 13 months. When PA had stabilized at 156 ± 14 mm Hg compared with a baseline of 128 ± 13 mm Hg (p < 0.001) urine flow rate (V), sodium excretion (UNaV), and chloride excretion (UClV) decreased in the constricted kidney (E), while creatinine clearance (CCr) and para-aminohippurate clearance (CPAH) did not change significantly. In the contralateral control kidney (C) V, UNaV, and UClV increased, in association with increases in CCr and CPAH, but without changes in filtration fraction or renal vascular resistance. Although E/C creatinine concentration (UCr) increased as E/C V fell, E/C urine sodium concentration remained unchanged. However, when differences in V, UNaV, UClV, CCr, CPAH, and UCr between C and E were enhanced in relation to a transient exaggerated increase in PA in the acute phase following R.A.C., E/C UNa appeared to decrease slightly. When collateral circulation which had developed to E was stripped, enhanced differences in separate renal function recurred in association with a further increase in PA. Thus, chronic R.A.C. leads to the development of collateral renal circulation which appears responsible for improvement in function in E, and decrease in PA. These effects are associated with decrease in function on the control side, thereby leading to a reduction in differences in function between the two sides.
Acute Effects of Cobalt on Cardiac Metabolism and Mechanical Performance
Authors: Huy N. D. , Morin P. J. , Mohiuddin S. M. , Morin Y.
Published: April 2011

The acute administration of 0.06 and 0.10 mM cobalt chloride to an isolated guinea pig heart perfused in vitro results in decreased mechanical performance and substrate uptake. These findings are concordant with those of others who suspect that cobalt slows down myocardial energy metabolism and, as a result, substrate uptake. Cobalt also increased coronary vascular tonus and, as a result, coronary resistance.