bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pressure‐Volume Characteristics of the Interstitial Fluid Space in the Skeletal Muscle of the Cat
Authors: Eliassen E. , Folkow B. , Hilton S. M. , ÖBerg B. , Rippe B. 
Published: December 2008

AbstractPressure‐volume characteristics of the interstitial fluid space in cat skeletal muscle were determined by plethysmographic recordings of the tissue volume changes following net capillary filtration or absorption. The concomitant changes in interstitial fluid pressure (Pif) were assessed by estimating the isovolumetric capillray pressure (Pci). In resting muscle Pci averaged 13.7 mni Hg during perfusion with blood, having an average colloid osmotic pressure of 18.3 mm Hg. As there is no net fluid exchange, these findings indicate a balancing filtration iorce of 4.6 mm Hg which is exerted chiefly by the colloid osmotic pressure of the tissue fluid (πif), with the possible contribution of a slightly subatmospheric Pif.A reduction of tissue fluid volume of 30 % led to a reduction of Pci of approximately 4 mm Hg, while doubling the volume raised Pci by 3–4 mm Hg. Since these Pci changes must be partly ascribed to alterations in πif, the actual changes in Pif were even smaller. The compliance of the interstitial fluid space in skeletal muscle is therefore high (above 1.4 ml/100 g tissue × mm Hg) within the normal range of Pif. The large extravascular fluid dept in skeletal muscle is thus easily mobilized to replenish the circulatory system when capillary pressure falls. as after a blood loss.
The Effect of Dopa on the Spinal Cord. 8. Presynaptic and “Remote” Inhibition of Transmission from Ia Afferents to Alpha Motoneurones
Authors: Bergmans J. , Burke R. , Fedina L. , Lundberg A. 
Published: December 2008

AbstractIn unanesthetized spinal cats, injected with l‐DOPA, intra‐axonal recording was used to investigate the primary afferent depolarization (PAD) evoked in different species of afferents by volleys in the flexor reflex afferents (FRA). It was confirmed that a late PAD is evoked in la afferents and usually not in Ib or cutaneous afferents. Some late PAD was observed in a few group II muscle afferents. Intracellular recording from motoneurones revealed a considerable depression of the Ia EPSP during the late PAD evoked from the FRA after DOPA, but it was diffkult to attribute this entirely to the PAD in Ia afferents since there was also a late postsynaptic conductance increase in the motoneurones. A further analysis was made on acute spinal cats not injected with DOPA, in which a late P.4D sometimes is evoked by FR24 volleys, without the late postsynaptic soma effects in motoneurones. The marked depression of the Ia EPSP evoked from the FRA under these conditions has a longer duration than the PAD in la afferent terminals. It is postulated that two mechanisms contribute to the Ia EPSP depression, presynaptic inhibition and “remote inhibition”; the latter action persisting after the repolarization of Ia afferents. The results are discussed in relation to reflex regulation of stepping.
Diurnal Variation of Serum Immunoassayable Thyrotropin (TSH) Concentration in the Rat
Authors: Leppäluoto J. , Ranta T. , Tuomisto J. 
Published: December 2008

AbstractThe diurnal variation in the immunoassayable TSH content of sera of female and male adult rats under conditions of 12 hours' light and 12 h darkness was determined. In the females the TSH level rose gradually from 11 p.m. to 3 p.m. and then declined, in the males the level rose from 7 p.m. to 11 a.m. and then declined. Scattering of individual values was great (mean coefficient of variation was 0.45–0.46). For the estimation of the serum TSH level these determinants should be known.
Longitudinal Propagation of Myogenic Activity in Rabbit Arteries and in the Rat Portal Vein
Authors: Bevan John A. , Ljung Bengt 
Published: December 2008

AbstractLongitudinal spread of induced activity was analysed in the rat portal vein and rabbit aorta and compared to propagation in the brachial, radial, ear, mesenteric, femoral and posterior tibial arteries of the rabbit. Isometric force in spiral strips or intact preparations was measured during superfusion with Krebs' solution. The lower 20 per cent of the preparation could be selectively exposed to exogenous noradrenaline (NA) or to transmural field stimulation. Propagation was inferred to occur when the amplitude of the local response, relative to that when the entire preparation was stimulated, exceeded the relative length of the locally stimulated tissue. No propagation was found in the rabbit aortic strip. Propagation was less in proximal than in distal muscular arteries. The calculated distance of propagation was greatest in the rat portal vein. The intact limb vessel preparations reponded to NA with phasic contractions. In the ear artery, here was propagation only of the first phase of this biphasic response. These results show that different sections of the rabbit vascular tree display individuality in their ability to support propagation. In general, propagation in the arterial tree appears to be greatest in the smaller vessels.
Effects of Changes in Plasma Volume and Osmolarity on Thermoregulation during Exercise
Authors: Nielsen Bodil 
Published: December 2008

AbstractPlateau values of deep body temperature were diminished during work after intake of 1 1/2 1 water, they were increased after intake of 2–3 % sodium chloride solution and after dehydration in a sauna by 1 1/2 kg. The shifts in plateau values were related to plasma osmolarity, not to plasma volume. In rest and during work at low temperature (7° C), when there was virtually no sweating, the effect of plasma osmolarity on body temperature disappeared. The rate of increase in sweating at the start of work was faster than normal after intake of water and slower after intake of sodium chloride solution and dehydration. The mechanism by which the changes in temperature were brought about is the increase in sweating at the start of work. Plasma osmolartiy may cause these changes either by a peripheral effect on the sweat glands or a central effect on the thermoregulatory centres.
The Effect of Glucagon on Hepatosplanchnic Hemodynamics, Functional Capacity, and Metabolism of the Liver in Gats
Authors: Krarup Niels , Larsen Jens Anker 
Published: December 2008

AbstractGlucagon in doses of 0.1, 0.5, and 5.0, μg/kg/min infused i.v. caused a marked increase in portal blood flow (up to 300 %) due to a dose‐dependent increase in conductance‐of gastrointestinal vessels, and an increase in the conductance in the hepatic low pressure vessels (up to 30 %), but only slight changes in hepatic arterial conductance and flow. Glucagon caused a decrease in the hepatic extraction of Indocyanine Green (ICG), no change in ICG clearance, an increase in bile acid secretion, but only minor changes in bile flow and ICG excretion. The splanchnic glucose output and ketone production were increased by glucagon. The cytoplasmic redox level was not affected, but the mitochondrial redox level was changed to a more oxidized state together with a 30 % rise in hepatic oxygen consumption and a correlated increase in ethanol elimination. These last effects were not dose‐dependent. It is concluded that the marked changes in splanchnic hemodynamics found during glucagon infusions, are not a consequence of the metabolic effects of the hormone on the liver, but rather a direct effect of non‐physiological concentrations of glucagon on gastrointestinal vessels. The results exclude any marked influence of glucagon on the intrahepatic distribution of blood flow and functional liver mass.
Effects of Ethanol, tert. Butanol, and Clomethiazole on Net Movements of Sodium and Potassium in Electrically Stimulated Cerebral Tissue
Authors: Wallgren H. , Nikander P. , Boguslawsky P. von , Linkola J. 
Published: December 2008

AbstractThe sodium and potassium contents of rat brain cortex slices incubated in bicarbonate medium were measured and the intracellular quantities estimated on the basis of the inulin distribution. Ethanol (109 mM) did not affect the ion content of unstimulated tissue during passive leakage in cold medium or aerobic incubation at 37oC.The effects of ethanol (109 mM), tert. butanol (34 mM) and clomethiazole (0.39 mM) were tested on the response to electrical stimulation (entry of sodium and loss of potassium in the non‐inulin space) as well as on the restoration of the ionic gradients occurring after a period of stimulation. All agents selectively inhibited the entry of sodium on stimulation with very little effect on potassium loss. The result is considered compatible with preferential action of the drugs on the activation step of the sodium channel controlling movement of sodium during the excitation cycle, and presumably located on the outside of the membranes. During recovery, no inhibition of sodium expulsion was observed, whereas both alcohols‐ but not clomethiazole‐slightly decreased the accumulation of potassium. Considered together with other observations, this finding suggests a special affinity of ethanol for the potassium binding site in the ion transport system.
Plasma Hyperosmolarity and Pulmonary Capacitance Vessels
Authors: Piene H. , Aarseth P. , Bo G. 
Published: December 2008

AbstractChanges in pulmonary blood volume have been looked for during increased plasma osmolality. Two different techniques, one involving freezing of whole rats, and the other with removal of separate lung lobes from cats, have been used. In both cases lung blood volume was calculated from content of 123I‐plasma albumin and 51Cr‐erythrocytes. Plasma osmolarity was increased 10–23 % by intravenous infusions of hyperosmolar solutions of NaCl or glucose. In the cat lung experiments vascular pressures and cardiac output were followed during i.v. infusions of 3 M NaCl or 3–5 M glucose solutions. The pulmonary vascular resistance decreased upon the injections, but no significant changes in pulmonary vascular volume could be detected. The extravascular lung water content decreased markedly during the hypertonic infusions. Also in the rat experiments the pulmonary blood volume seemed to be unchanged during hyperosmolarity.
Disappearance of 133Xenon and 125Iodide and Extraction of 86Rubidium in Subcutaneous Adipose Tissue during Sympathetic Nerve Stimulation
Authors: Linde Birgitta , Gainer John L. 
Published: December 2008

AbstractEffects of sympathetic nerve stimulation on the disappearance rates of 133Xenon and 125Iodide from a local depot as well as on the extraction of 86Rubidium from blood have been studied in the subcutaneous adipose tissue of dogs during constant blood flow perfusion. Resting mean k‐values for 133Xenon were 0.0040 min‐1(n = 10) and for 125Iodide 0.0386 min‐1(n = 5) while the PS‐products for 86Rubidium had a mean value of 2.5 ml × min‐1X 100 g‐1(n = 17). During sympathetic nerve stimulation a frequency dependent decrease of disappearance rates and PS‐products was found. The latter were reduced by an average of 30 % while the reductions of the disappearance rates were twice as large and similar for 133Xenon and 125Iodide. These results suggest a decrease in the perfused capillary surface area during sympathetic nerve stimulation.
The Action Potential in End‐Plate and Extrajunctional Regions of Rat Skeletal Muscle1
Authors: Thesleff S. , Vyskoil F. , Ward M. R. 
Published: December 2008

AbstractIn the innervated rat diaphragm muscle, the maximum rate of rise of the action potential was approximately 20 % greater in the end‐plate region as compared to non‐junctional areas. This difference in rate of rise was maintained for a period of at least 14 days after denervation. Desensitization of the post‐junctional membrane by carbachol or irreversible blockade of the cholinergic receptor system by use of a toxin from Naja naja siamcnsis failed to reduce this difference. When TTX (10‐6M) was added to the bathing fluid, action potentials could no longer be elicited from innervated fibres; a sodium‐dependent local response remained in most fibres, however, but only in the end‐plate region. After surgical denervation, the action potential becomes partially resistant to the blocking action of TTX, and it was found that the action potential in the end‐plate region was more resistant than that in non‐junctional areas. The results show the presence of TTX‐insensitive ionophores situated in the postjunctional membrane of innervated and denervated muscle fibres. It is suggested that these TTX‐insensitive sites contribute to the observed greater rate of rise of action potentials elicited from these areas.
Method for Gravimetric Registration of Changes in Tissue Volume
Authors: Grände P.‐O. , Järhult J. , Mellander S. 
Published: December 2008

AbstractA technique is described by which changes of tissue volume of a muscle region enclosed in a plethysmograph can be followed in terms of water displacements measured with an electronic gravimetric transducer. Experimental tests show that the method provides accurate recordings of vascular capacitance responses and of transcapillary fluid movements.
Action of Drugs on the Innervated and Denervated Urinary Bladder of the Rat
Authors: Elmer Mats 
Published: December 2008

AbstractIn the normally innervated rat bladder methacholine, acetylcholine, adrenaline and phenylephrine elicited contraction of the detrusor musclein situ,while isoprenaline caused relaxation. The response to noradrenaline varied but was most often relaxation. Experiments with dihydroergotamine and propranolol indicated the presence of both excitatory a‐receptors and inhibitory β‐receptors in the detrusor muscle. The bladder developed supersensitivity to parasympathomimetic agents and in the case of a‐receptor mediated effects also to sympathomimetic agents after parasympathetic decentralization and denervation, and after sympathetic denervation. Regarding the adrenergic β‐receptor effects, however, no supersensitivity developed after any of the denervation procedures. Parasympathetic denervation or decentralization uncovered a contractile response to noradrenaline most often masked by predominant relaxation in the normal bladder.
Characteristics and Distribution of Spinal Focal Synaptic Potentials Generated by Group II Muscle Afferents
Authors: Fu T. C. , Santini M. , Schomburg E. D. 
Published: December 2008

AbstractThe location of the segmental relays of group II afferents in the spinal cord was investigated by recording extracellular “focal synaptic potentials” (FSP), generated by group II afferents in the gastrocnemius‐soleus nerve. Three types of group II FSPs were differentiated by their location and latency. (1) The “dorsal group II FSP” was located in the dorsal horn dorsolateral to the intermediate nucleus. Its short latency from the incoming group II volley (0.6‐1.0 ins; led to the conclusion that at least the onset is monosynaptically generated. (2) The “ventral group II FSP” was found between the intermediate nucleus and the motor nucleus. This type of FSP had a longer central latency ranging from 1.2‐2.5 ms, which made it difficult to decide whether the linkage was monosynaptic or disynaptic. However, when considering other results (Fu and Schomburg 1974) it seems probable that the ventral FSPs in the low range of central latencies were generated monosynaptically. (3) The “late group II FSP” had a long and varying central latency and was found over a wider region although less regularly than the other FSPs. Presumably the late FSP represents the postsynaptic effect in second and third order neurones. It seems likely that at least the main part of the investigated dorsal and ventral group II FSPs was generated by secondary afferents from muscle spindles.
Protein Concentration and Colloid Osmotic Pressure of Rat Skeletal Muscle Interstitial Fluid
Authors: Aukland K. , Johnsen H. M. 
Published: December 2008

AbstractProtein concentration and colloid osmotic pressure (COP) were estimated in the fluid contained in nylon wicks after implantation in skeletal muscle of rats for 1 to 3 h. After 1 and 2 h implantation wick fluid showed an albumin/total protein ratio of 0.44, compared to 0.61 in plasma. Average concentrations relative to that of plasma were 0.37 for albumin, 0.52 for total protein, and 0.76 (calculated by difference) for non‐albumin protein. After 3 h implantation these ratios had increased significantly to 0.49, 0.69 and 1.07 respectively, presumably indicating beginning inflammation. The unexpected “excess” of non‐albumin wick fluid protein had an electrophoretic mobility like that of plasma β‐globulins, but its origin,‐from plasma or muscle‐is uncertain. Wick fluid COP averaged 8.7 mm Hg, as compared to a plasma COP of 18.9 mm Hg.
Storage of Elastic Energy in Skeletal Muscles in Man
Authors: Asmussen Erling , Bonde‐Petersen Flemming 
Published: December 2008

AbstractThe question, if muscles can absorb and temporarily store mechanical energy in the form of elastic energy for later re‐use, was studied by having subjects perform maximal vertical jumps on a registering force‐platform. The jumps were performed 1) from a semi‐squatting position, 2) after a natural counter‐movement from a standing position, or 3) in continuation of jumps down from heights of 0.23, 0.40, or 0.69 m. The heights of the jumps were calculated from the registered flight times. The maximum energy level, Eneg, of the jumpers prior to the upward movement in the jump, was considered to be zero in condition 1. In condition 2 it was calculated from the force‐time record of the force‐platform; and in condition 3 it was calculated from the height of the downward jump and the weight of the subject. The maximum energy level after take‐off, Ep0s, was calculated from the height of the jump and the jumper's weight. It was found that the height of the jump and Epos increased with increasing amounts of Eneg, up to a certain level (jumping down from 0.40 m). The gains in Epos over that in condition 1, were expressed as a percentage of Eneg and found to be 22.9 % in condition 2, and 13.2, 10.5, and 3.3 % in the three situations of condition 3. It is suggested that the elastic energy is stored in the active muscles, and it is demonstrated that the muscles of the legs are activated in the downward jumps before contact with the platform is established.
Glycogen Utilization in Leg Muscles of Men during Level and Uphill Running
Authors: Gostill D. L. , Jansson E. , Gollnick P. D. , Saltin B. 
Published: December 2008

AbstractGlycogen depletion was followed in the soleus, gastrocnemius, and vastus lateralis muscles of 3 men during 2 h of treadmill running on the level and uphill (+6o). One subject also ran downhill (‐4.5o). Running speed was adjusted in each condition to require 75% of the subjects' Vo2 max. Glycogen concentrations were similar in all 3 muscles at rest. From PAS staining glycogen appeared to be evenly distributed between slow and fast twitch fibres. A glycogen depletion of 17, 33, and 44 mmol of glucose units X kg‐1 wet weight occurred in the vastus lateralis, soleus, and gastrocnemius muscles, respectively, after running on the level. These values were 55, 46, and 60 mmol X kg‐1, respectively, after uphill running. Glycogen depletion in the soleus and gastrocnemius muscles after downhill running was similar to that after running on the level, however, in the vastus lateralis it was intermediate to that for uphill and level running. A loss of PAS stain was observed first in the slow twitch fibres in all conditions. The results support the concept of a differential involvement of the leg muscles during running which can be modified by running either uphill or downhill. Thus it is of importance for the representativity of a sample that it is taken from a particular muscle when the local response to exercise or physical training is studied.
Middle Ear Muscle Effects on Cochlear Responses to Bone‐conducted Sound
Authors: Irvine D. R. F. , Wester K. G. 
Published: December 2008

AbstractContractions of the stapedius and tensor tympani muscles were elicited by electrical stimulation of their motor nerves or of the muscles themselves in anesthetized cats. The effects of these contractions on cochlear microphonic responses to air‐ and bone‐conducted sound were examined. Stapedius contractions that produced changes in air conduction similar to those observed under physiological conditions had almost identical effects on bone conduction. Tensor tympani effects on bone conduction were of similar magnitude but greater complexity than those on air, and varied as a function of the location of the bone conductor on the skull. Control observations established that the effects were attributable to the middle ear muscles and not to other consequences of the experimental procedures, and that they did not reflect modification of an air‐conduction component of the bone‐conduction stimulus. The functional significance of these effects is discussed in terms of protection against masking of environmental sounds by self‐generated bone‐conducted sound.
Transcapillary Passage of Plasma Proteins in Experimental Burns
Authors: Ganrot Karin , Jacobsson Sten , Rothman Ulf 
Published: December 2008

AbstractThe “leakage” of proteins from plasma to interstitial fluid in burns was studied experimentally in dogs. The concentration of orosomucoid, α1‐antitrypsin, albumin, haptoglobin, IgG, β1C‐globulin and α2‐macroglobulin were determined in plasma and in lymph from the leg before and after scalding of the paw. The lymph/plasma ratio of all proteins except that of α2‐macroglobulin increased after scalding, indicating an increased capillary permeability to proteins with molecular weights up to 300,000.
DDT and Related Substances: Effects on Permeability Properties of Myelinated Xenopus Nerve Fibre. Potential Clamp Analysis
Authors: ÅRhem By Peter , Fraxkexhaeuser Berxhard 
Published: December 2008

AbstractAn analysis was made of the effect of DDT and related substances on the membrane currents associated with step changes of the membrane potential. The substances tested are: DDT, DDD, DDE, DDMU, DDA, DDCN, bis‐(p‐chlorophenyl)‐acetamide and polychlormated bi‐phenyls (PCB). DDT. DDA and bis‐(p‐chlorophenyl)‐acetamide had acute effects on permeability parameters of the nerve membrane. The effects of the substances differed drastically from each other. DDT affected the turn off process of the sodium permeability mechanism after a positive potential step; the effect was large on fibres from Rana pipiens but negligible on fibres from Xenopus laeris. DDA affected the turn off process of the potassium permeability mechanism while bis‐“p‐chlorophenyl‘‐acetamide affected sodium and potassium permeability constants, Pxa and PK. The other substance; tested had no or only marginal acute effects. The main effect of DDA may be described as a specific effect on the rate constant βn. The obvious differences in effects of the substances on the permeability parameters were thus related to defined minute molecular differences of the studied substances.
Changes in Pulmonary Vascular Volumes after Induced Intravascular Aggregation of Blood Platelets
Authors: Vaage J. , Aarseth P. , Enge I. , Hognestad J. 
Published: December 2008

AbstractThe volumes of intra‐ and extravascular fluid compartments in lungs have been studied in cats after intravascular aggregation of blood platelets induced by collagen infusions. Such infusions give marked pulmonary pressor responses. A biopsy‐technique with removal of isolated lobes after isotopelabelling of the blood, indicated an increased vascular volume during the response to a collagen‐infusion, while the extravascular water content remained unchanged. Angiographic observations revealed that the increased vascular volume is due to distension of large arteries, while the veins have a somewhat reduced dimension. These findings are interpreted as being caused by a precapillary vasoconstriction, no marked changes on capillary pressure, and with passive arterial dilatation upstreams to the constricted segments. Venous narrowing might be active or due to some passive recoil.