bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cell Volume as a Factor Influencing Electrical and Mechanical Activity of Vascular Smooth Muscle
Authors: Johansson Börje , Jonsson Olof 
Published: December 2008

ABSTRACTThe effects of variations in the extracellular osmolarity on the electrical and mechanical activity of the isolated rat portal vein were studied. Addition of sucrose or xylose (20–100 mmoles/l) to the “normal” solution caused inhibition of contractile activity which could be ascribed to changes in the electrical discharge pattern. Increasing osmolarity with urea produced transient inhibition, return to control activity, and, on return to normal solution, a transient excitation. Reducing osmolarity by 30–60 mOsm/l by decreasing the [Na+] and [Cl] of the medium caused sustained excitation with continuous spike discharge and tetanic contraction. Comparable decreases in the ionic concentrations but with osmotic substitution by sucrose or xylose had little influence on muscle activity. Substituting Na+ and Cl with urea on an equiosmolar basis caused excitation resembling that in hypoosmotic solution. If the smooth muscle cells are looked upon as osmotic cells with membranes that are freely permeable to H2O and urea but less permeable to sugar and ions, the results indicate a consistent correlation between cell volume and state of activity; shrinkage associated with inhibition, swelling with excitation. Changes in the transuiembrane concentration gradients for K+, Na+ and Cl‐, caused by the cellular volume changes, are not sufficient to explain the electrical responses. Changes in ionic membrane permeability are assumed to occur.
Secretory Responses and Respiratory Enzymes of the Rat's Submaxillary Gland after Repeated Teeth Amputations
Authors: Ohlin Per , Perec Carlos Jose 
Published: December 2008

AbstractThe effect of repeated teeth amputations on the secretory responses and the activities of succinic dehydrogenase, cytochrome oxidase and fumarse was studied in the rat's submaxillary gland.Repeated teeth amputations cause and enlargement of the gland.The secretory responses to adrenaline were found to be increased while those to acetylcholine, methacholine or stimulation of the parasympathetic secretory nerve were unchanged.The total activities of succinic dehydrogenase and fumarase were increased while that of cytochrome oxidase was unchanged.
Effect of Corticosterone and 11‐Desoxycortisol on the Extra‐Adrenal Chromaffin Tissue of the Rat
Authors: Lempinen Matti , Ojala Kari 
Published: December 2008

AbstractRepeated injections of hydrocortisone and cortisone completely prevent the postnatal degeneration of extra‐adrenal chromaffin tissue of the rat, while treatment with desoxycorticosterone (DOC) is without such an effect.Also with massive doses of adrenocorticothropic hormone (ACTH) disappearance of the extra‐adrenal chromaffin cells can be prevented (Lempinen 1964).In the present study the effect of corticosterone and 11‐desoxycortisol on the postnatal chromaffin tissue have been studied.
Static Load‐Length Characteristics of Aortic Strips from Hypertensive Rabbits
Authors: Aars Harald 
Published: December 2008

AbstractElevated threshold and reduced sensitivity of aortic baroreceptors in hypertensive rabbits (Aars 1968) might be due to changes in the aortic wall, which is known to become stiffer in chronic hypertension.Since resetting of baroreceptors was present when studied a few days after development of hypertension, the static load‐length relationship of circular aortic strips from the receptor area was investigated in vitro.The strips from the hypertensive rabbits were thicker than normal when stretched by 3 g, and had higher elastic modulus than the strips from normal rabbits.Although not strictly comparable to in vivo conditions, the results suggest that at the same blood pressure, the aortic baroreceptors would be less stimulated in the hypertensive than in the normal rabbit, and that a given elevation of mean blood pressure would produce a greater increase of baroreceptor activity in the normal than in the hypertensive animal.Thus, the changes demonstrated in the aortic wall after 3–15 days of arterial hypertension may explain the resetting of aortic nerve activity in the hypertensive rabbits.
On the Physiological Significance of the Amplitude of the Endosomatic Galvanic Skin Reaction (GSR) in the Cat
Authors: Lang A.H. 
Published: December 2008

AbstractEndosomatic galvanic skin reactions (GSR) evoked by electrical stimulation of the distal stump of a sectioned sciatic nerve have been recorded with metal macroelectrodes.It has been established that the amplitude of the negative phase of the endosomatic GSR is determined by (i) the stimulation parameters, (ii) the location of the recording electrodes, and (iii) the neuro‐sudomotoric activity before the stimulation.In addition, the GSR is influenced by both (iv) spatial summation and (v) temporal summation or cumulation, and may be influenced (vi) by the area of contact between the electrodes and the skin.On the basis of earlier and new observations in the recording of GSR's the conclusion has been drawn that the negative phase of the endosomatic GSR recorded with a macroelectrode is a composite potential which is produced in a circuit of resistive elements and unit potential generators (UPG), a group of effector cells that are probably situated in the wall of the sweat channel.The UPG's, each of which produce a unit potential (UP), seem to be coupled in parallel to each other and in series with the surface electrode.
Effect of pH and Temperature on the Uptake of Monoamines by Mouse Peritoneal Mast Cells in Vitro.
Authors: Jansson Sten‐Erik 
Published: December 2008

AbstractThe uptake of 5‐hydroxytryptamine, 5‐hydroxytryptophan, noradrenaline and dopamine by normal mouse peritoneal mast cells was studied by means of the histochemical fluorescence method.It was found that 5‐hydroxytryptamine uptake was significantly depressed by increasing pH from 7.0 to 8.9 and by lowering temperature to 20d̀ C when the amine concentration in the incubation medium was 1 μ/ml but not when the concentration was 10 μ/ml.The 5‐hydroxytryptophan uptake was to a high degree affected by similar pH and temperature alterations even when the concentration was as high as 200 μ/ml.This probably reflects a depression of the 5‐hydroxytryptophan decarboxylase activity.Noradrenaline and dopamine uptake was not significantly affected by pH or temperature alterations.These results indicate that normal mouse peritoneal mast cells take up 5‐hydroxytryptamine by an active as well as by a passive process and that the fluorescence observed after incubation with 5‐hydroxytryptophan is due to a high degree to decarboxylation into 5‐hydroxytryptamine.Noradrenaline and dopamine are apparently taken up by diffusion.Dopamine is taken up to some degree also by cells other than mast cells.
Dynamic Analysis of Muscle Spindle Endings in the Cat Using Length Changes of Different Length‐Time Relations
Authors: Lennerstrand Gunnar , Thoden Uwe 
Published: December 2008

AbstractPrimary and secondary muscle spindle endings in the ankle extensors of the cat were studied in response to length changes of ramp, triangular wave, sine wave and parabolic wave form with the intention of finding the most suitable input signal for an extensive dynamic analysis of the spindle during constant fusimotor input.In dynamic tests the spindle endings were not found to obey linear length‐response transfer functions; no support for a power function relation could be obtained.Sine wave analysis was therefore not considered suitable for the purpose of determining the transfer functions.Attention was directed towards the use of step changes of velocity and of acceleration of length changes.No evidence for a specific sensitivity to acceleration was found in responses to ‘parabolic’ length changes.Responses interpreted as due to mechanical properties in the spindle elements resembling ‘stiction’ were obtained when ‘ramp’ length changes were applied.These effects were largely avoided when recurring ‘triangular’ length changes of constant velocity were used.It is concluded that the dynamic analysis might be adequately performed by subjecting the musscle spindles to periodically recurring length changes of triangular wave form giving step changes in velocity.
Changes in the Filtration Fractions in the Superficial and Deep Venous Drainage Area of the Cat Kidney due to Fluid Loading
Authors: Nissen O. I. 
Published: December 2008

AbstractThe effect of Ringer and mannitol loading on the filtration fractions of plasma entering the superficial and the deep part of the cortex was investigated by comparing the plasma concentrations of inulin and protein in the blood leaving the two venous drainage areas with the concentrations in arterial blood. The ratio between the deep and the superficial filtration fraction (FFD/FFS) decreased by some 20 per cent mainly due to a decrease in FFD. Inside the juxtamedullary glomeruli, which constitute a part of the glomeruli of the deep area, short‐circuits between the afferent and the efferent arterioles have been described, which cause the medullary blood supply to partly by‐pass the sites of ultrafiltration. The blood leaves the juxtamedullary glomeruli via relatively thick muscular efferent arterioles which regulate the medullary blood flow. The decrease in FFDmay result from a preferential augmentation of the flow through the medulla,viz.this indicates that the overall filtration fraction of the deep drainage area to a larger degree is governed by the presumably low filtration fraction of the juxtamedullary glomeruli
Posthypertonic Hemolysis in Sodium Chloride Systems
Authors: Zade‐Oppen A. M. M. 
Published: December 2008

AbstractHuman erythrocytes were exposed in vitro to hypertonic NaCl solutions and then to near isotonic media. The resulting posthypertonic hemolysis was studied as a function of hypertonic concentration and of time in the hypertonic medium. Providing that a critical concentration level (˜1.5 M NaCl) is exceeded, posthypertonic hemolysis is proportional both to the duration of exposure to hypertonicity and to the hypertonic concentration. The results have been interpreted in terms of a hypothesis put forward by Söderström (1944), who postulated that influx of salt occurred during the hypertonic phase and that a later reduction of the external concentration of 0.65 M NaCl will an influx of salt occur. An analysis of the results in terms of this hypothesis suggested that the permeability of the cells to NaCl increases with increasing external NaCl concentration: The permeability increase was very great in the region of 3 M NaCl. The counter‐current multiplier mechanism for kidney function has been criticised on the ground that red cells may not tolerate the tonicity changes postulated to exist in the kidney. In vitro experiments using slightly worse conditions than are believed to exist in the human kidney showed no significant hemolysis
The Reflection of the Age, Tissue and Solubility on the Amberlite CG‐50 Fractions of Denatured Collagens
Authors: Kulonen E. , Pikkarainen J. 
Published: December 2008

AbstractCollagen was extracted and purified from the skins of young and full‐grown guinea pigs and from the skins and tendons of calf and cow, first with neutral salt solutions and acidic buffers in the cold and then the residue was gelatinized by stepwise heating. In the young animals the collagenous material which could be solubilized at +65°C already was increased markedly. The various denatured collagens were fractionated with Amberlite CG‐50 columns, eluted with buffers of increasing ionic strength and pH and finally with sodium hydroxide. The first fraction, emerging at pH 5.50, was large in the samples from soluble collagen (in comparison to insoluble), in the extracts from insoluble collagens of young animals (in comparison to adults) and in the collagenous fractions of tendon (in comparison to the skin). The gradient‐buffer‐eluted fraction which had been derived from insoluble collagen at progressively raised temperatures contained in abundance imino acids and hydroxy amino acids (in comparison to soluble collagens).
Position and Velocity Sensitivity of Muscle Spindles in the Cat. II. Dynamic Fusimotor Single‐Fibre Activation of Primary Endings
Authors: Lennerstrand Gunnar , Thoden Uwe 
Published: December 2008

AbstractImpulse frequency responses of cat primary muscle spindle endings to ‘triangular’ length changes were recorded during stimulation of single dynamic fusimotor γ‐fibres at a constant rate. Endings in the ankle extensor and flexor muscles were studied. The dynamic fusimotor effects consisted of an unchanged or decreased position sensitivity of the endings and an increased velocity sensitivity to length increment. The effects were quantitatively similar in primary endings of all the muscle studied. In the velocity response, which was subdivided into ‘quick’ and ‘slow’ components, the ‘slow’ velocity response was increased much more by the stimulation than the ‘quick’ velocity response. The velocity sensitivity to length decrement could usually not be exactly determined. In the few cases in which it could be assessed, it seemed to be lower than the velocity sensitivity to length increment. When relatively high rates of stimulation and high velocities of length change were applied to the endings, a velocity dependent ‘saturation’ of the response appeared. In the discussion interest is focused on spindle mechanisms responsible for generating the observed response. It is suggested that the response is derived from intrafusal components with the mechanical and electrical characteristics of amphibian slow muscle fibres.
Afferent and Efferent Activity in the Renal Nerves of Cats
Authors: Astrom A. , Crafoord J. 
Published: December 2008

AbstractIn anesthetized cats efferent as well as afferent activity has been recorded in the kidney nerves. Pulse synchronous bursts of efferent impulses could regularly be recorded which after vagotomy and baroreceptor denervation were augmented and changed into a continuous type of discharge. The efferent activity could be modified by electrical stimulation of peripheral sensory nerves. It was inhibited by elevation of systemic blood pressure by i.v. noradrenaline injection, and greatly increased by lowering of blood pressure by i.v. acethylcholine. In the same nerves afferent activity also occurred, in a few instances spontaneously, but more often after elevation of renal vein pressure, elevation of arterial perfusion pressure (by pump), mechanical pressure applied to the hilus area or local dilution of the blood by close intra‐arterial injection of Ringer solution. Local ischemia for one minute or less elicited intense afferent activity. The results indicate that venous distension and increased subcapsular pressure are adequate stimuli for these afferent responses and that more than one kind of fibers are engaged in the afferent response. The functional significance of the afferent activity remains to be determined.
Influence of Puromycin and Anoxia on the Effect of Gonadotrophins on Ovarian Carbohydrate Metabolism
Authors: Ahrén Kurt , Hamberger Lars , Rubinsteini Lidia 
Published: December 2008

AbstractAn analysis of certain requirements for the gonadotrophic stimulation of ovarian carbohydrate metabolism has been performed. Whole ovaries from prepubertal and hypophysectomized rats were incubated in bicarbonate or Tris‐HCl buffer at 37° C. Puromycin, injected to the rats either before removal of the ovaries or added directly to the incubation medium, blocked the protein synthesis in the ovaries and caused a decrease in the rate of glucose uptake and lactic acid production. The stimulatory effects, however, of both LH and FSH on carbohydrate metabolism, which have been reported in detail previously (Hamberger and Ahrkn 1967) were not blocked by puromycin. Furthermore, this effect of FSHin vitroon carbohydrate metabolism could not be explained as due to a contamination by LH in the FSH preparation used. Ovaries incubated under anaerobic conditions showed increased rates of glucose uptake and lactate production. LH had no stimulatory effect on lactate production under these experimental conditions while puromycin still caused a significant decrease of this parameter. Addition of 2,4‐dinitrophenol to the medium markedly enhanced lactate production by the ovaries. Possible mechanisms for the gonadotrophic stimulation of carbohydrate metabolism in the ovary are discussed.
The Mechanisms behind the Rapid Blood Volume Restoration after Hemorrhage in Birds
Authors: Djojosugito1 Ahmad M. , Folkow Björn , Kovách Arisztid G. B. 
Published: December 2008

AbstractThe mechanisms responsible for the more efficient volume restoration after hemorrhage in birds as compared with mammals were studied in experiments on ducks. The results suggest that qualitativsly similar mechanisms operate to mobilize tissue fluid in ducks as in cats (see Öberg 1964). The most important factor seems to be a strong reflex vasoconstriction in the skeletal muscles, increasing considerably the pre‐ to postcapillary resistance ratio with a fall in capillary pressure as a result. In this way net fluid absorption is reflexly initiated in the tissue which contains the largest tissue fluid reservoir in the body. At the same time the pre‐capillary sphincters become secondarily relaxed, increasing the capillary surface area available for absorption. When in the course of a large blood loss arterial and venous pressures become reduced as well, this will further lower capillary pressure and do so in all tissues, thus enhancing fluid absorption. The results indicate that, from a quantitative point of view, considerable differences exist between ducks and cats. First, the reflex vasoconstriction and the subsequent capillary pressure fall are more pronounced in duck skeletal muscle. Second, the capillary surface area is approximately three times larger in duck muscle. These circumstances imply especially favourable conditions for rapid fluid absorption. It is probable that the greater resistance to blood loss and shock of most bird species as compared with mammals is directly related to their much greater capacity for fluid mobilization from the skeletal muscles.
The Effect of Mannitol, Sucrose, Raffinose and Dextran on Posthypertonic Hemolysis
Authors: Zade‐Oppen A. M. M. 
Published: December 2008

AbstractInhibition of the hemolysis that occurs after first increasing and then decreasing the concentration of solutes in the surrounding medium of human red blood cells (posthypertonic hemolysis) was studied inin vitroexperiments with regard to its possible importance for blood preservation by freezing procedures; hemolysis after freezing and thawing is considered to be mainly due to such variations in solute concentrations (Lovelock 1953). All the tested substances,viz. mannitol, sucrose, raffinose and dextran, gave a substantial decrease in hemoglobin (Hb) liberation. The effect of such substances when used as additives in studies of blood preservation by freezing may thus have found an additional explanation. The low molecular weight substances decreased Hb liberation mainly by reducing the number of hemo‐lysed cells. Dextran, however, decreased the amount of Hb liberated from the individual cell without an apparent decrease in the number of damaged cells. Thus when Hb liberation is decreased by the use of dextran, this reduction may not be a good measure of the damage to the cell population. The consistency of the results with a hypothesis for the mechanism of posthypertonic hemolysis is discussed. Assuming this hypothesis to be correct, the inhibitory effects of non‐penetrating additives seem, at least partially, to be also explicable.
Innervation by Nerve Implants of “Fast” and “Slow” Skeletal Muscles of the Rat
Authors: Fex S. , Jirmanová Isa 
Published: December 2008

AbstractThe time course of innervation by nerve implants of the fast contracting flexor digitorum longus and the slow contracting soleus muscles were studied by the recorcling of isometric twitch tensions in response to stimulation of the implanted nerve and by histochemical visualization of newly‐formed end‐plates. When a foreign motor nerve was implanted into a muscle 30 days prior to sectioning of the original nerve supply, synaptic contacts were established 4–8 days after the section of the nerve, while, with simultaneous implantation and denervation, 16 days were required for the implanted nerve to innervate the muscle. Implantation of the nerve which normally innervates the flexor digitorum longus muscle into the soleus altered the contraction and relaxation speeds of the soleus muscle towards those of a fast contracting muscle, the change being apparent as soon as 4–8 days following sectioning of the original nerve. In muscles with nerve implants and intact normal innervation hypertrophy occurred, amounting to 20–30 per cent within one month.
Pulmonary Diffusing Capacity Limiting Human Performance at Altitude
Authors: Blomqvist Gunnar , Jr Robert L. Johnson , Saltin Bengt 
Published: December 2008

AbstractIn 6 internationally successful endurance athletes measurements of oxygen uptake, and pulmonary diffusion capacity at maximal bicycle exercise were performed at sea level and after 3 weeks stay at 2250 m altitude (Mexico City). Maximal oxygen uptake was 10–17 % lower at altitude and this reduction was related to the ratio at sea level between DLCO/max Vo2, The findings demonstrated that there is a physiological basis not only for a more marked reduction of max Vo2 in welltrained groups at altitude but also for the observed large differences in performance at altitude between athletes of equal capability at sea level.
Single Unit Recordings from Muscle Nerves in Human Subjects
Authors: Hagbarth K.‐E. , Vallbo A. B. 
Published: December 2008

AbstractSingle‐unit impulses were recorded with semi‐microelectrodes from muscular portions of peripheral limb nerves in awake human subjects. Thirteen units were studied. Four of them could not be activated by mechanical peripheral stimuli but they fired steadily during sustained voluntary contractions. They were considered to be either motor fibres or proprioceptor units, having high thresholds to mechanical stimuli. The other nine units were shown to be proprioceptors which had their end organs located in deep structures of the leg or the forearm. They were divided into three groups on the basis of their responses to local mechanical stimuli, passive movements, and voluntary contractions. Possible relations between each group of units and various anatomical types of proprioceptors are discussed. Some of the units had characteristics which suggested that they were muscle spindle afferents. The findings reported in this investigation and in an earlier investigation, dealing with multi‐fibre discharges in muscle nerves, indicate that the muscle spindle afferent discharge is increased during voluntary contractions and thus, that the fusimotor system is engaged in voluntary motor acts.