bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effects of Intraperitoneally and Intravenously Administered Pentobarbitone Anesthesia on Pulmonary and Splanchnic Blood Volumes in Rats. An Evaluation Carried out before and after Standardized Blood Losses
Authors: Aarseth P. 
Published: December 2008

AbstractPulmonary and splanchnic blood volumes have been examined with the use of suitable radioactive isotopes in rats anesthetized with either intraperitoneally or intravenously administered pentobarbitone (30 mg/kg b.w.). The blood volumes in the two vascular areas were evaluated both in non‐bled rats and in animals which had been exposed to a 12 % or a 24 % reduction of the total blood volume. Organ blood content was examined after sudden circulatory arrest which was achieved by rapid freezing of the whole animal in liquid nitrogen. I. p. anesthetized non‐bled rats had a smaller splanchnic blood volume and a larger pulmonary blood volume than the i.v. anesthetized rats. The large lung blood volume of i.p. anesthetized rats was markedly reduced upon a 12 % blood loss. A 24 % blood loss caused moderate additional pulmonary blood volume reductions. Also in the i.v. anesthetized animals the lung blood volume was relatively more reduced during a small bleeding than during a large one. A 12 % blood loss here caused only small volume changes in the splanchnic vascular bed, whereas a marked blood volume reduction occurred in this area after a 24 % blood loss. It appears that the pulmonary vascular bed of the rat is very sensitive to changes in total blood volume, and that it easily alters its capacitance in parallel with total blood volume changes.
The Metabolism of Liver Cholesterol in the Young Chick
Authors: Svanberg Olof , Svedjelund Anders 
Published: December 2008

AbstractA mixture of 14C‐4‐cholesterol and 14C‐26‐cholesterol was injected into the invaginated yolks of newly hatched chicks which were then placed in metabolism chambers. By tracing the label in expired air, excreta (faeces+urine) and in their carcasses, the main pathways for the metabolism of the liver cholesterol could be estimated quantitatively. Over a period of 10 days about 26 % of the administered chclesterol was catabolized to bile acids, about 19 % was eliminated from the body as neutral steroids in the excreta and at the end of the 10th day about 55 % was retained in the carcasses. About 85 % of the bile acids synthesized was recovered in the excreta. As much as 45 % of the radioactivity derived from the 14C‐4 cholesterol in the excreta was associated with the neutral steroids, while 55 % was found in the bile acid fraction. The rate of bile acid biosynthesis estimated from the 14CO2‐production decreased from the fifth day after hatching. No estimation could be carried out during the days immediately following injection until isotopic equilibration had been reached. The faecal excretion of neutral steroids increased rapidly up to the fifth day, after which time it decreased. The body appears to treat part of the pre‐formed cholesterol from the yolk as a surplus which has to be eliminated. The specific activity of the cholesterol in the excreta collected on the 10th day was only about half of that of the intestinal content analyzed at the end of the same day.
Content of Blood and of Extravascular Water in Cat Lungs during Changes in Total Blood Volume
Authors: Bø P. Aarseth G. 
Published: December 2008

AbstractA method has been developed which allows alterations in lung blood content and in extravascular lung water to be studied. The 2 upper lung lobes were removed separately from open‐chested cats. The first lobe was taken for control evaluations. The second one was removed when the circulatory situation had been changed. Labelled erythrocytes and plasma albumin had been injected beforehand. From the content of isotopes in the lung lobes, their blood volume could be calculated. Extravascular water was found by taking the difference between wet and dry weight of lung tissue, and correcting this difference for the blood content in that lobe. When total blood volume was reduced by a small bleeding, lung extravascular water content was reduced, and there was also a small reduction in lung blood volume. After a larger bleeding lung blood content was markedly reduced while the extravascular lung water content was then somewhat increased. Augmcntation of total blood volume by a blood transfusion led to an increase in lung blood volume, but to a decrease in extravascular lung water content.
Pulmonary Blood‐ and Extravascular Water Volumes during Prolonged Post‐Hemorrhagic Systemic Hypotension
Authors: Aarseth P. , Bø G. 
Published: December 2008

AbstractIn cats prolonged hemorrhagic hypotension had been shown to increase the pulmonary arterial pressure and vascular resistance. Pulmonary extravascular water volume and pulmonary blood volume have been evaluated early and late in such a period of post‐hemorrhagic hypotension. 51Cr‐labelled erythrocytes and 125I‐labelled albumin were injected intravascularly to animals with an opened chest and on positive pressure ventilation. One upper lung lobe was then suddenly clamped, removed and frozen. The lung lobe tissue and a simultaneously taken blood sample from a large vessel were measured for total w‐eight, dry weight and tracer content. The lobe's blood volume and extravascular water volume were then calculated per unit extravascular lung dry weight. A second lung lobe was removed and treated similarly at a later stage. 1 /2 h after the blood loss there was a marked reduction in lung blood volume and at the same time some increase in pulmonary extravascular water volume indicating constriction of postcapillary capacitance vessels. After 3 h of hypotension pulmonary extravascular water volume was found to be the same as before the hemorrhage although the pulmonary arterial pressure increased. This indicated that the increase in vascular resistance must predominantly be due to vasoconstriction at precapillary sites. The reduction in the lungs' blood volume remained at these late stages indicating that capacitance vessels were still constricted. When hyperinflations of the lungs were omitted in the experimental period, there was a tendency towards water accumulation in the lungs.
Single Glomerular Blood Flow as Measured with Carbonized 141‐Ce Labelled Microspheres
Authors: Källskoo Ö. , Ulfendahl H. R. , Wolgast M. 
Published: December 2008

AbstractThe blood flow to single cortical and juxtamedullary glomeruli was investigated in “normal” rats by means of a microsphere technique. Radioactively labelled microspheres were injected retrogradely into the ascending aorta and the number of spheres trapped in the glomeruli at different levels of the cortical parenchyma was determined by gamma‐spectrometry and related to the number collected from a catheter in the femoral artery. A uniform sphere size and no aggregates in the injected bolus were essential requirements for accurate blood flow determinations. The spheres were separated by sedimentation in water, which reduced the size range from a nominal value of 15±5 μ to 16.9±2.65 μ and gave no aggregates in the sedimented sample. The single glomerular perfusion was estimated to be 0.23 μl/min and 0.20 μl/min for cortical and juxtamedullary glomeruli, respectively. The difference was not significant (P > 0.5). The values correspond to estimations of total renal blood flow in the present and previous investigations.
The Functional Ultrastructure of the Blood‐Lymph Barrier. Computer Analysis of Data from Dog Heart‐Lymph Experiments using Theoretical Models.
Authors: Arturson G. , Groth T. , Grotte G. 
Published: December 2008

AbstractA generalized two‐pore model including differences in permeability, surface area and pressure conditions along the capillary, was formulated and certain simplifications were tested with respect to their influence on the estimated parameters. A simplified version of the model was tested for compatibility and parameter confidence against a series of macromolecular sieving data obtained from Starling dog heart‐lung preparations. In these experiments heart‐lymph was collected during steady state conditions and the venous pressure was changed.During “normal” conditions the blood lymph barrier of the dog heart‐lung preparations could be adequately described by an equivalent two‐pore membrane with small pores of radius 35–60 Å, and an additional set of larger pores of radius 120–160 Å, with the density of one large pore per 10,000 small pores. The mean transcapillary pressure difference was calculated to be less than 1 cm H2O.During elevated venous pressure the effective surface area for fluid exchange was found to decrease to 1/2–1/3 of the normal value, due to a pronounced decrease in small pore radius. The concomitant increase in large pore radius caused an increased flow of fluid through the large pores. These results, in addition to the corresponding pressure perturbation data, have given some support to the pressure compensatory mechanisms suggested by Wiederhielm (1968).The hypothesis that the transport of macromolecules takes place by way of cytopempsis was shown to be tenable if the ad hoc assumption was made that the vesicle size or density is pressure dependent.
In vitro Studies on the Uptake of Biogenic Amines by Rat Mast Cells
Authors: Heisler Seymour , Uvnäs Börje 
Published: December 2008

AbstractMast cells from rat peritoneal and thoracic cavities were isolated and incubated with biogenic amines (dopamine [DA], noradrenaline [NAa] and 5‐hydroxytryptamine [5‐HT]) or their precursor amino acids. Competition for uptake, saturation of mast cell amine stores (for 5‐HT and DA), and blockade of uptake by metabolic inhibitors indicate that simple passive diffusion does not suffice to explain the uptake by mast cells of the amines studied. The uptake of 5‐HT and DA appears to primarily involve active transport, whereas the uptake of Hi and NA may preferentially operate by facilitated diffusion.
Differential Effect of para‐Chlorophenylalanine on the Two Slow Wave Sleep Stages in the Cat
Authors: Ursin Reidun 
Published: December 2008

AbstractThe effect of an injection of 200 mg/kg para‐chlorophenylalanine (PCPA) on sleep was studied in 6 cats 48—72 h after the injection. Each cat was also given a control injection of the vehicle (BRIJ 35) 3 weeks before or after the experimental dose, in a balanced order. The main effect of PCPA was a reduction of the deep slow wave sleep (DSWS), with little effect upon the light slow wave sleep (LSWS) or rapid eye movement (REM) sleep. Both the number and the length of the DSWS episodes were reduced. For LSWS, only the length of the episodes was reduced. The number and the length of the REM sleep episodes were not changed. When the DSWS was reduced to 10 % or less of control values, there was a tendency to a decrease of LSWS and REM sleep also.
Cardiac Noradrenaline Turnover and Urinary Catecholamine Excretion in Trained and Untrained Rats during Rest and Exercise
Authors: ÖStman Ingegerd , Sjöstrand Nils O. , Swedin Göran 
Published: December 2008

AbstractRats were trained by daily swimming (1—2 h) during 15 weeks. The training caused a significant increase in heart weight. Cardiac noradrenaline (NA) and adrenal catecholamine (CA) contents were significantly increased in trained animals. When exposed to acute prolonged exercise the endogenous levels of cardiac NA decreased in untrained, but not in trained, rats. Resting cardiac NA turnover, as measured by rate of disappearance of exogenous3H‐NA, was slower in trained than in untrained rats (T1/2= 52 h and 20 h, respectively). The NA turnover increased during exercise, but still remained slower in trained rats. Figures were obtained indicating a significantly lower initial uptake of exogenous NA in the hearts of trained rats. Resting excretion of CA in the urine was not different in trained and untrained rats, while the increase seen after a period of exercise was much greater in the untrained animals. The results indicate that chronic physical training induces a functional adaptation of the sympathicoadrenal system leading to a better transmitter economy during exercise. The nature of this adaptation remains, however, unsettled.
In Vitro Work Load and Rat Heart Metabolism: III. Effect on ribosomal aggregation
Authors: Hjalmarson A. , Isaksson O. 
Published: December 2008

AbstractIn two preceding papers increased pressure load (afterload) was found to accelerate whole heart protein synthesis and amino acid transport in the perfused working rat heart (Hjalmarson and Isaksson 1972, Ahren et at. 1972). To further analyse this effect, sucrose gradient analysis of the postmitochondrial supernatant was performed to evaluate reactions involved in the ribosome cycle. When hearts were perfused in vitro under control conditions with buffer containing normal plasma levels of amino acids and with glucose as substrate, levels of polysomes decreased and levels of ribosomal subunits increased. These findings together with a decreased rate of protein synthesis indicated that a block in initiation of peptide chains had developed during perfusion. Perfusion of hearts with increased afterload increased the levels of polysomes and decreased the levels of ribosomal subunits and accelerated protein synthesis. The effects were obtained both when glucose and palmitate were used as substrate. Insulin further increased the levels of polysomes in pressure overloaded hearts and the ribosome profiles attained by overload in presence of insulin were identical to those obtained from unperfused hearts. Increased levels of polysomes and decreased levels of ribosomal subunits together with an increase in protein synthesis suggested that pressure overload stimulated reactions involved in the initiation of polypeptide chains. It is concluded that increased pressure load increases levels of initiation factors or changes the activity of enzymes regulating initiation processes in the ribosome cycle.
The Dynamic Properties of the Acoustic Middle Ear Reflex in Nonanesthetized Rabbits. Quantitative Aspects of a Polysynaptic Reflex System
Authors: Borg Erik 
Published: December 2008

AbstractThe open‐loop dynamic characteristics of the total acoustic middle ear muscle reflex (m. stapedius and m. tensor tympani) and of the isolated acoustic m. tensor tympani reflex were determined in unrestrained nonanesthetized rabbits. The frequency domain transfer functions of the reflexes were calculated on the basis of the responses to the onset and the decay of tone bursts independently. These functions had lowpass character and could be described by second‐order differential equations including a transport delay. The parameters of the equations were intensity dependent. At equal stimulus intensity the isolated m. tensor tympani reflex was slower than the total reflex. When the higher threshold of the m. tensor tympani was compensated for, the difference became small. The decay of the total reflex response was considerably slower than was the onset, decay of the isolated rn. tensor tympani reflex only slightly slower than its onset. The phase shift of the transfer functions for onset was greater than for decay possibly indicating a slip in the system. The closed‐loop properties of the total reflex and those of the isolated m. stapedius reflex were found to be closely similar. In addition, it was pointed out that the reflexes are slow in consideration to the small mass of the muscles, but that the dynamic properties seem to be well adapted to suit certain features of the afferent auditory system.
Depression of 3H‐Glucose Uptake into Rabbit Polymorphonuclear Leukocytes by Glucocorticoids in Concentrations Partly Saturating the Specific Glucocorticoid Uptake. Evidence for a Glucocorticoid Receptor
Authors: Simonsson Bengt 
Published: December 2008

AbstractRabbit polymorphonuclear leukocytes have a specific glucocorticoid uptake in vitro, half saturated by cortisol at a probably physiological concentration (about 3 × 10‐9 M). These cells in vitro accumulate 3H‐d‐glucose and 3H‐2‐deoxy‐d‐glucose, possibly by a common uptake step. Cortisol, dexamethasone, 9αF‐prednisolone, prednisolone, triamcinolone and triamcinolone acetonide, all in the low concentrations sufficient to partly saturate the specific glucocorticoid uptake, depress the uptake of 3H‐glucose by these cells. Corticosterone acted as a partial agonist. 11‐epicortisol, tetrahydrocortisone and progesterone, which have no glucocorticoid activity, had a very low activity on 3H‐d‐glucose uptake. For 11‐epicortisol and tetrahydrocortisone this corresponded to a low affinity to the specific glucocorticoid uptake process, while progesterone had a relatively high affinity. Progesterone in high concentrations was shown to block the depressing effect on 3H‐d‐glucose uptake by cortisol, probably by keeping it away from the specific glucocorticoid uptake process. Rabbit polymorphonuclear leukocytes thus seem to have a specific glucocorticoid receptor.
Plasma‐Kinins and Adrenergic Vasodilatation in the Submandibular Salivary Gland of the Cat
Authors: Gautvik K. M. , Kriz M. , Lund‐Larsen Kari 
Published: December 2008

AbstractThe submandibular salivary gland of the cat has been perfused in situ at constant volume inflow and in such a way that perfusion periods with kininogen‐containing and with kininogenfree perfusates alternated. The gland was stimulated with close arterial injections of nor‐adrenaline and the secretory and vascular responses recorded. Doses of noradrenaline which caused vasodilatation or no vascular effects when cat kininogen was present in the perfusate induced brisk vasoconstrictor responses in the same gland when a kininogen‐free perfusate was used. The vasoconstrictor responses could be gradually reduced and finally abolished as the gland was reloaded with cat kininogen. Glands which had undergone repeated stimulations with noradrenaline had a markedly lower content of kallikrein than had the contralateral, unstimulated organ. It is concluded that during adrenergic stimulation of the submandibular salivary gland, kallikrein is released into the interstitial space where it induces formation of plasmakinins. The plasma‐kinins formed cause vasodilatation, and they probably play an important role in the vasodilator response observed after a period with activation through the sympathetic nerves.
Choline Acetyltransferase in Salivary Glands after Surgical and Chemical Sympathectomy
Authors: Ekström Jörgen 
Published: December 2008

AbstractAn increase of the total activity of choline acetyltransferase occurs in the dog's parotid and in the submaxillary glands of the golden hamster and mouse after a surgical postganglionic sympathetic denervation. No such increase was found in the guinea‐pig's submaxillary gland; nor was it found in the rat's parotid and sublingual glands. A gradual enzyme increase was shown to begin after about 15 days in the rat's submaxillary gland. A chemical sympathectomy with 6‐hydroxydopamine had a similar effect as a surgical denervation; an enzyme increase was noticed in the rat's submaxillary but not in the sublingual gland. It is concluded that in the same species one type of gland may show the enzyme increase, while another type remains unchanged. A low enzyme concentration and a high density of adrenergic nerve fibres seem to favour the increase of the activity of choline acetyltransferase.
Repetitive Impulse Firing: Comparisons between Neurone Models Based on ‘Voltage Clamp Equations' and Spinal Motoneurones
Authors: Kernell Daniel , Sjöholm Hans 
Published: December 2008

AbstractRepetitive impulse firing was elicited in neurone models by steady stimulating currents of abrupt onset. The neurone models were based on the Frankenhaeuser—Huxley equations (1964) for voltage clamp data from the amphibian peripheral nerve. A frequency‐current curve (‘f‐I curve’), initial adaptation, and minimum firing rate similar to those of cat spinal motoneurones were obtained in the Frankenhaeuser—Huxley model if it were provided with (i) a long‐lasting after‐hyperpolarization due to potassium permeability changes, and (ii) a decreased subthreshold sodium inactivation. For detailed comparisons to the repetitive impulse firing of spinal motoneurones, model versions were used in which the subthreshold sodium inactivation was very slight, and the passive membrane properties as well as the afterpotentials resembled those of spinal motoneurones. In their repetitive behaviour, these models were quantitatively similar to spinal motoneurones. In the motoneurone‐like model versions, initial adaptation was due to a kind of ‘summation’ of the potassium permeability changes underlying the after‐hyperpolarizations of consecutive spikes. The slope of the f‐I curve was markedly affected by modifications of the size or time course of the potassium permeability changes responsible for the after‐hyperpolarization.
Spectral Sensitivity of the Compound Eye in a Moth. Intra‐and Extracellular Recordings
Authors: Struwe Göran 
Published: December 2008

AbstractThe spectral sensitivity of the compound eye in a moth (Manduca sexta) was tested electrophysiologically by extracellular recordings in the wavelength region 310 to 650 nm, a) during dark‐adaptation, and b) during exposure to violet (408 nm) and red (680 nm) light. Sensitivity maxima were found at 370 to 390 nm, 450 to 470 nm, and 530 to 550 nm. During exposure to violet light a larger decrease in sensitivity was found for the maxima at 370 to 390 nm and 450 to 470 nm compared to that at 530 to 550 nm. During exposure to red light a larger decrease in sensitivity was found for the latter maximum. The results are interpreted as evidence for at least two photoreceptor types with different spectral sensitivity maxima. Intracellular recordings from single photoreceptors showed maxima in the same wavelength regions as those found extracellularly. The spectral sensitivities obtained were approximately similar. The homogeneity of the intracellular recordings is suggested to be due to interreceptor coupling.
Choline Acetyltransferase and Gholinesterase in the Pancreatic Duct of the Cat
Authors: Ekström Jörgen , Lenninger Sven 
Published: December 2008

AbstractCholine aecetyltransferase has been demonstrated in the duct and parenchyma of the pancreatic: gland of the cat. Potentiation of the effect of acetylcholine on the contractility of ductal segments has been observed after eserinization, indicating the presence of cholinesterase in the duct. These findings are considered to indicate that the pancreatic duct of the cat is cholinergically innervated.
Role of Cyclic AMP and Ca++in Mechanical and Metabolic Events in Isometrically Contracting Vascular Smooth Muscle
Authors: Andersson Rolf 
Published: December 2008

AbstractIn bovine mesenteric artery catecholamines stimulated simultaneously adrenergic α‐and β‐receptors. The relaxation induced by a specific adrenergic β‐receptor stimulation was associated with an increased content of cyclic AMP, a phosphorylaseaactivation and a decrease of the content of ATP and creatinephosphate (CrP). No effect on the high energy phosphate compounds was present in the Ca++‐poor artery, but the effect on cyclic AMP and phosphorylase was still evident. Sotalol blocked all the actions induced by adrenergic β‐receptor stimulation. The contracting action induced by selective adrenergic α‐receptor stimulation was initially associated with a decrease of the cyclic AMP content, but when the tension was maximally developed, after 120 s, the cyclic AMP content was increased and the phosphodiesterase activity reduced. In Ca++‐poor artery a cyclic AMP decreasing effect was still present after 120 s and there was no reduction of the phosphodiesterase activity. The mechanical and metabolic effects induced by α‐receptor stimulation were blocked by dibenamine. Histamine, which increased the artery tension, significantly reduced the cyclic AMP content after 15 s, but after 5 min the level of cyclic AMP had increased and phosphorylaseawas activated. The mechanical and metabolic effects of histamine were blocked by promethazine, an antihistaminic drug. The role of cyclic AMP in relaxation and contraction of vascular smooth muscle is discussed.