bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic Properties of Excitation and Inhibition in the Cochlear Nucleus
Authors: Møller Aage R. 
Published: December 2008

AbstractThe dynamic properties of inhibition and excitation of single units in the cochlear nucleus were studied using tones that were amplitude modulated either sinusoidally or with pseudorandom noise. The cross‐correlation analysis of the unit discharge rate and the pseudorandom noise modulation of the stimuli showed that the dynamic properties determined from the responses to a single modulated excitatory tone (at CF), to a modulated excitatory tone together with an unmodulated inhibitory tone (above CF), and to a modulated inhibitory tone together with an unmodulated excitatory tone were almost identical with regard to latency as well as to delay of the peak of the cross‐covariance function. On the basis hereof it is inferred that the inhibition is either a cochlear phenomenon or that it is transmitted over pathways with identical temporal properties as those of the excitation. When 2 tones were presented simultaneously the modulation of the excitatory tone usually gave a higher degree of modulation of the discharge rate than did modulation of an inhibitory tone. Addition of an unmodulated inhibitory tone to a modulated tone at CF resulted in an extension of the range of intensities over which the maximal gain was relatively constant. In many units this range extended from about 10 dB above the unit's threshold to 60 dB or more above.
Consequence of Social Isolation on Blood Pressure, Cardiovascular Reactivity and Design in Spontaneously Hypertensive Rats
Authors: Hallbäck Margareta 
Published: December 2008

AbstractSpontaneously hypertensive rats (SHR), which inherently display exaggerated cardiovascular defence reactions to environmental stimuli (Hallbäck and Folkow 1974), and normotensive control rats (NCR) were kept isolated after they were weaned to reduce such environmental influences which normally induce psychological activation. Mean arterial pressure was followed until 7 months of age, when the cardiovascular defence reactions to acute mental stress were compared and an analysis of cardiovascular design was made. The isolated SHR but not the isolated NCR, had significantly lower pressures than their unisolated controls. Likewise, judged by the relative weight of the left ventricle and the hemodynamically evaluated design of the hindquarter resistance vessels, the structural cardiovascular adaptation was about proportionally less pronounced in isolated than in control SHR. However, their cardiovascular responses to acute “psychological stress” were equally intense, and clearly exaggerated when compared with NCR. Thus, a prolonged reduction of excitatory environmental influences implies a relatively less pronounced development of hypertension in SHR, even though an inherent hyperreactivity concerning neurohormonal pressor responses to alerting stimuli is present. These findings stress the importance of interacting intrinsic‐hereditary and extrinsic neurogenic influences for the initiation of primary hypertension.
Distribution of an Adenohypophysial Constituent in the Body II. Quantitative Tissue Distribution in the Rat
Authors: Hall Håkan , Lakomaa Eeva , Kihlström Jan Erik 
Published: December 2008

AbstractA peptide with a molecular weight of about 5 000 has previously been shown to affect the output of semen in frogs and probably also in mammals. This sperm‐releasing substance is not part of any known gonadotropic hormone. The tissue distribution of this substance has been investigated. The iodinated substance has been injected into rats and the radioactivity content of the different tissues has been determined. lodinated rat albumin has been injected into other rats, to determine the content of blood in the different tissues. A formula has been derived to obtain a figure for real accumulation, using the radioactivity content of the blood and of the tissues after injection of the sperm‐releasing substance and albumin, respectively. The sperm‐releasing substance is incorporated into the adenohypophysis. neurohypophysis. liver, kidney, lung, ovary, uterus and some male sexual organs. The causes for this distribution are discussed.
Effect of Alloxan‐diabetes on the Metabolism of Rabbit Colon Smooth Muscle
Authors: Arnqvist Hans J. 
Published: December 2008

AbstractThe metabolism of colon smooth muscle from normal and alloxan‐diabetic rabbits was studied in vitro. Glucose uptake, incorporation of glucose‐14C into glycogen and incorporation of leucine‐14C into protein were determined. These three parameters were all depressed in diabetic smooth muscle incubated in a medium containing 5.6 mM glucose. Raising the glucose concentration in the medium to 22.2 mM almost doubled the glucose uptake both in diabetic and normal smooth muscle and at this glucose concentration no significant difference in this parameter was found. Insulin (0.1 U/ml) added in vim) stimulated glucose uptake, incorporation of glucose‐14C into glycogen and incorporation of leucine‐14C into protein in diabetic colon smooth muscle. Insulin stimulated glucose uptake to the same degree in normal and diabetic colon smooth muscle, while its effect on glucose‐14C and Ieucine‐14C incorporation tended to be somewhat more pronounced in diabetic colon muscle.
The Influence of Acute Normovolemic Anemia on Cerebral Blood Flow and Oxygen Consumption of Anesthetized Rats
Authors: Borgström Lars , Jóhannsson Halldór , Siesjö Bo K. 
Published: December 2008

AbstractThe influence of acute normovolemic anemia on cerebral blood flow (CBF) and cerebral metabolic rate for oxygen (CMRO2) was studied in normocapnic rats under nitrous oxide anaesthesia. The arterial hemoglobin content was reduced to values of about 12, 9, 6 and 3 g.(100 ml)‐1 by arterial bleeding and substitution with equal volumes of homologous plasma. The CBF increased in proportion to the reduction in hemoglobin content to reach values of 500–600 per cent of normal at extreme degrees of anemia, but CMRO2 remained unchanged. Cerebral venous PO2 and oxygen saturation did not decrease below normal values, indicating that tissue hypoxia did not develop. However, since the increase in CBF at hemoglobin concentrations of below 9 g . (100 ml)‐1 was far in excess of that expected from the decrease in viscosity the results indicate that dilatation of cerebral resistance vessels occurred. This dilatation, which was obviously related to the fall in arterial oxygen content, cannot be explained by any of the current theories proposed to explain cerebral hyperemia in hypoxia.
The Distribution of Sodium in Aortic Walls from Spontaneously Hypertensive and Normotensive Rats
Authors: Jonsson Olof , Lundgren Yen , Wennergren Göran 
Published: December 2008

AbstractThe contents of exchangeable sodium, bound sodium and total water and the extracellular space of thoracic aortas from normotensive and spontaneously hypertensive rats were measured. The aortas from the hypertensive rats contained more sodium than those from the normotensive animals while the total water content and extracellular space in the two groups were the same. The capacity to bind sodium in an osmotically inactive form was greater in the aortas from the hypertensives than in those from the normotensives. The difference in binding capacity was of the same order of magnitude as the difference in sodium content, indicating that the excess sodium in the thoracic aortas from the hypertensive rats was osmotically inactive and thus unable to cause water logging.
Arterial Pressure, Cardiac Output and Systemic Resistance before and after Pithing in Normotensive and Spontaneously Hypertensive Rats
Authors: Albrecht I. , Hallbäck M. , Julius S. , Lundgren Y. , Stage L. , Weiss L. , Folkow B. 
Published: December 2008

AbstractAfter complete cardiovascular denervation mean arterial pressure (MAP) falls to almost equally low levels in spontaneously hypertensive rats (SHR) and normotensive control rats (NCR). This has earlier been suggested to indicate a dominance of neurogenic mechanisms in established SHR hypertension.–In the present study, total peripheral resistance (TPR) remains, however, some 35 per cent higher in adult SHR than in NCR after pithing while cardiac output (CO), and stroke volume, is 35 per cent lower in SHR. These opposite differences in TPR and CO after denervation, resulting in equal MAP levels in SHR and NCR, seem rather to be a consequence of the rapidly established structural adaptation that affects all SHR high‐pressure cardiovascular sections. Thus, the SHR precapillary resistance vessels display thick‐ ened walls and luminal narrowing, which keeps TPR higher than in NCR even during maximal vaso‐ dilatation. Due to hypertrophy, the SHR left ventricle exhibits a reduced myocardial stretch for a given filling pressure and stroke volume is consequently reduced more than in NCR after complete denervation.–Paradoxically, therefore, rather than reflecting any dominance of neurogenic mechanisms in established SHR hypertension the MAP equalization in SHR and NCR after cardiovascular denervation emphasizes the hemodynamic importance of cardiovascular structural changes present in hypertension.
Studies of Some Twitch and Fatigue Properties of Different Motor Unit Types in the Ankle Muscles of the Adult Cat
Authors: Hammarberg C. , Kellerth J‐O. 
Published: December 2008

AbstractContractile responses of motor units in the gastrocnemius, soleus and pretibial flexor muscles of adult cats were elicited by intracellular stimulation of motoneurones. The motor units were classified into types FF, FR and S (Burke et al. 1971) and their responses to the same stimulation patterns as those used in a previous investigation of whole muscles (Hammarberg and Kellerth 1975 a) were studied. The duration of motoneurone afterhyperpolarization was short in both the fast twitch FF and FR units; it was longer in the soleus S units than in the S units of the pale muscles. Twitch time‐to‐peak was less than 30 ms in the FF and FR units, but exceeded 40 ms in the S units. Soleus S units were slower than S units of the pale muscles. Potentiation was observed in the gastrocnemius units, but not in the soleus S units. A short rest allowed fatigued extensor units of the FF and FR types to regain some contractile strength. This was less evident in the S units which, on the other hand, were extremely resistant to fatigue. Differences in response patterns between corresponding motor unit types of the flexor and extensor muscles were observed. A few fast twitch units were identified in the slow soleus muscle.
Effect of Bulbar Acidification on Gastric Acid Responses to Urecholine in Pavlov Pouch Dogs
Authors: Nilsson Göran 
Published: December 2008

AbstractDogs were provided with mucosal septal pouches of the fundic stomach and of the duodenal bulb. Gastric secretion was stimulated by intravenous infusion of submaximal doses of porcine gastrin or the stable choline ester Urecholine. Acid perfusion of bulbar pouches profoundly inhibited acid responses to gastrin. Bulbar acidification produced little or no reduction in acid secretion induced by Urecholine. Small doses of Urecholine do not release gastrin in the dog but may induce acid secretion, mainly by direct cholinergic stimulation of the HC1 glands. The fact that Urecholine‐induced acid secretion was not inhibited in the present experiments is consistent with the hypothesis that the bulbar mechanism does not interfere with cholinergic stimulation acting on the parietal cells.
Reversibility of Effects of Very Hypotonic Fluids on in Vitro Frog Gastric Mucosa: A Functional and Morphological Study
Authors: Helander H. F. , Sanders S. S. , Shanbour L. L. , Rehm W. S. 
Published: December 2008

AbstractFunctional and morphological properties of the in vitro frog gastric mucosa were studied during and after exposure to very hypotonic (≅ 25 mOsM) solutions. Within 20 min the acid secretory rate decreased to zero, but it returned to normal levels after isotonic fluids had been restored. The potential difference (PD) dropped within the first minutes after the exposure to hypotonic solutions, and became inverted. Following the return of isotonic conditions the PD increased to levels higher than in the controls. The electrical resistance increased about 10–fold during the hypotonic period, but decreased to near normal values when isotonic conditions were restored. By light and electron microscopy the cells of the hypotonic mucosae appeared greatly swollen, and the alterations were assessed by morphometric methods. The gland lumina were almost obliterated, and the lamina propria was reduced to about 60% of its former volume. After the return to isotonic conditions normal morphology was restored. It is conceivable that the great increase in resistance during the hypotonic period was caused by the occlusion of the gland lumina. Quantitative analyses of the Na, K, and C1 tissue concentrations indicated a large loss of these ions during the hypotonic state. Presumably the epithelial cells in the hypotonic mucosae avoid bursting by rapidly letting large numbers of ions exit, which results in a cellular osmolarity close to that of the bathing fluids.
Effect of Elevated Interstitial Pressure on the Renal Cortical Hemodynamics
Authors: Källskog Ö. , Wolgast M. 
Published: December 2008

AbstractThe influence of renal interstitial pressure on the resistance pattern within the superficial cortical vasculature has been investigated from determinations of I) the glomerular blood flow with a modified microsphere technique and 2) the intravascular hydrostatic pressures.Interstitial pressure was monitored via a 50 μm PVC‐catheter placed into the subcapsular interstitial space. Two conditions were analyzed viz. a) elevation of iiretheral pressure to 20 mm Hg and b) venous stasis to 10–15 mm Hg. Both conditions produced an increase in the interstitial pressure from 1–2 mm Hg to about 5 mm Hg as well as an increased hilar lymph flow and protein flow of about the Same size. The vascular reactions were different, however. Urethcral stasis (but not the stasis of a single nephron) produced a decreased resistance in the afferent arteriolae with a concomitant increase in the pressures in the glomerular capillaries, and the peritubular capillary network. In contrast, venous stasis produced only small changes in the parameters studied but for the obvious rise in the peritubular capillary pressure.The results suggest that factors other than the interstitial pressure are governing the afferent vascular tone; the tubular wall tension might he one of these factors.
Comparison of the Effects of Physical Exercise, Cold Acclimation and Repeated Injections of Isoprenaline on Rat Muscle Enzymes
Authors: Harri M. N. E. , Valtola J. 
Published: December 2008

AbstractThe metabolic effects on rat cardiac and skeletal muscle of a strenuous program of swimming, of cold acclimation and of isoprenaline treatment (0.3 mg/kg daily for 5 five‐day weeks) were compared. Exercised and cold‐exposed rats gained less body weight than did controls or isoprenaline‐treated rats. In all treated groups the heart and the interscapular brown adipose tissue hypertrophied. The size of the adrenals increased only in isoprenaline‐treated animals. Cold‐acclimation and physical training increased and isoprenaline treatment reduced or did not affect the activities of succinate dehydrogenase, rnalate dehydrogenase and citrate synthase of cardiac muscle. In skeletal muscle all treatments resulted in increased activities of these enzymes. Of the anaerobic enzymes analysed, only the activity of hexokinase increased in response to the treatments used. This increase was the same in cardiac as in skeletal muscle, but it was significantly greater with isoprenaline‐treatment than with training or with cold‐acclimation. The activities of lactate dehydrogenase and phosphofructokinase did not differ significantly. All treatments improved cold resistance, but only swimming exercise and cold acclimation significantly increased tolerance to exercise. It is concluded that prolonged stimulation of adrenergic β‐receptors by catecholamines is responsible for the metabolic changes observed.
Gastric Acid Secretion in a Teleostean Fish A Method for the Continuous Collection of Gastric Effluence from a Swimming Fish and its Response to Histamine and Pentagastrin
Authors: Holstein Björn 
Published: December 2008

AbstractGastric acid secretion has been measured in the codfish (Gadus morhua) equipped with a catheter draining the stomach, by titrating the water swallowed by the fish. Unstimulated acid secretion was found to be very low; in most fishes not exceeding 8 μmol H+/kg.h. Intramuscular injection of histamine evokes a dose‐dependent secretion of gastric acid, with a maximum acid output of 300 μmol/kg.h occurring with 10 mg/kg histamine dihydrochloride. No acid response was obtained with pentagastrin.
On the Mechanism of Inhibitory Action of Vibrations as Studied in a Molluscan Catch Muscle and in Vertebrate Vascular Smooth Muscle
Authors: Ljung Bengt , Hallgren Per 
Published: December 2008

AbstractIn previous studies longitudinal vibrations have been found to reduce active force development in smooth muscle, possibly due to a direct action on the contractile mechanism. In the present experiments the inhibitory effect of vibrations on isometric tension was studied in isolated preparations of the rat portal vein, the rabbit thoracic aorta and the anterior byssus retractor muscle (ABRM) of the Mytilus edulis, The results demonstrate that vibrations of appropriate frequency and amplitude caused prompt inhibition of contractile tension and that complete recovery of active force normally occurred after cessation of vibration in vertebrate smooth muscle as well as during the phasic contraction of ABRM. However, in the “catch” of the ABRM there was no regain in force following the vibration induced inhibition. The contractile proteins are considered to be in a locked state during the catch situation. Thus, this contracted state seems to be released by vibrations. It is therefore concluded that vibrations do interfere with the interrelationship between the myofilaments. This conclusion supports the previously forwarded hypothesis that vibrations act by increasing the rate of detachment of actin‐myosin crosslinks in vertebrate smooth muscle.
Thermoregulation during Static Work with the Legs
Authors: Nielsen Bodil 
Published: December 2008

AbstractSustained static work with the legs, i.e., holding a weight of about 10% of maximal isometric strength for 25 min was compared to dynamic exercise on a bicycle ergometer causing the same rate of heat production.In the static work the subjective feeling of exertion was very high and the effort maximal. The pronounced increase in heart rate and blood pressure and a typical flush of the face and chest (flush areas) indicated a high sympathetic tonus. Plasma catecholamine levels were 1.3 times higher (significant at the P ≤ 0.05 level) after static work than after dynamic work. Although the sustained static work was nearly maximal, the rate of increase in sweating and the change in core temperature during work were not different from the responses to dynamic work.
Synthesis of Brain‐Specific Acidic Proteins in Rat and Mouse Cerebral Slices
Authors: Wroński Andrzej , VON DER DECKEN ALEXANDRA 
Published: December 2008

AbstractOptimal conditions for incorporation of radioactive amino acids into protein by slices of brain have been established. Protein synthesis continued for at least 4 h at 35°. The highest incorporation of amino acids into protein was obtained with 20–50 mg wet weight per ml incubated at pH 7.1. After incubation of 500 mg of slices acidic proteins were separated by saltfractionation and electrophoresis on 14% polyacrylamide gel. The most acidic band was shown to contain S‐100 protein. Identification was solubility of the protein in 100% (NH4)2SO4, electrophoretic mobility at pH 8.9, precipitation with specific antibodies, and 2‐dimen‐sional electrophoresis in polyacrylamide gel. The protein band was insoluble in 50 % methanol and contained between 0.06 and 0.2% of the radioactivity present in the total soluble proteins; while other well separated acidic proteins contained about 10 times the radioactivity of S‐100 protein.
On the Effects of Gymnemic Acid in the Hamster and Rat
Authors: Hellekant Göran , Gopal V. 
Published: December 2008

AbstractThe gustatory activity of the chorda tympani proper nerve has been recorded before and after the application of gymnemic acid to the tongue of hamster and rat. Concentrations of pure gymnemic acid ranging from 1 mg/ml to 10 mg/ml have been used. In the hamster gymnemic acid suppressed the response to solutions of sucrose especially, but it also caused, at higher concentrations, a general suppression of the taste response. The depression caused in the response to sucrose was directly related to the strength of the gymnemic acid and inversely to that of the sucrose solution. In the rat a suppression of the response to saccharin was obtained but no suppression of the taste response to sucrose by gymnemic acid was observed.
Dynamic Properties of Primary Auditory Fibers Compared with Cells in the Cochlear Nucleus
Authors: Møller Aage R. 
Published: December 2008

AbstractThe dynamic properties of the responses of single primary auditory fibers were compared with those of single cells in the cochlear nucleus. The stimuli were tones (at the unit's characteristic frequency, CF) that were amplitude‐modulated with pseudorandom noise. The dynamic properties were described by the cross‐covariance and integrated cross‐covariance functions between the recorded discharge rate and the modulation. These two measures have earlier been shown to be valid approximations of the system's impulse and step response function, i.e. the change in discharge rate in response to a short impulsive increase (or decrease) in the stimulus intensity and a step increment (or decrement) in the stimulus intensity. The cross‐covariance function computed from the responses of fibers had a narrower peak than that of cells indicating that a brief change in stimulus intensity gives rise to a faster change in the discharge rate of fibers than that of cells. The modulation of the discharge rate of cells for a certain degree of amplitude modulation of the sound is usually greater than that of fibers. The range of stimulus intensities where a change in stimulus intensity gives rise to a change in discharge rate is smaller for fibers (about 30 dB) than what was shown earlier for cells (70–80 dB). The cross‐covariance function computed from the slow wave responses recorded from the surface of the cochlear nucleus in response to an amplitude‐modulated tone has individual peaks that reflect distinct classes of units with regard to latency of unit discharges.
Molecular Forms of Gastrin in Antral Mucosa, Plasma and Gastric Juice during Vagal Stimulation of Anesthetized Cats
Authors: Uvnäs‐Wallensten K. , Rehfeld J. F. 
Published: December 2008

AbstractGastrin was released by electrical vagal stimulation in anesthetized cats. Antral mucosa, blood and gastric juice samples collected during vagal stimulation were subjected to gel filtration in order to characterize the different molecular forms of gastrin. In antral mucosa component III (gastrin‐17) predominated. Besides, the antrum contained 5 per cent component II (gastrin‐34, “big” gasirin), I per cent component I and trace amounts of component IV (gastrin‐14 or “mini” gastrin). Immediately after vagal stimulation, component III (gastrin‐17) appeared in the gastric venous effluent followed within a few minutes by component IV (gastrin‐14). Component I and II (gastrin‐34) were not detectable in any of the plasma samples. We suggest that component III (gastrin‐17) is released from the antral mucosa and is then rapidly metabolized to component IV (gastrin‐14) possibly to a significant extent in the fundic region of the stomach. Large amounts of component III (gastrin‐17) were found in the vagally‐induced gastric juice. Only very small amounts of degradation products were present, indicating that cat gastrin is relatively resistant to peptic degradation and acid hydrolysis.