bluuebunny/crossref_metadata_2025_split huggingface dataset:
Motility of the Urinary Bladder in Cats during Filling at Physiological Rates II. Effects of Extrinsic Bladder Denervation on Intramural Tension and on Intravesical Pressure Patterns
Authors: Klevmark Bjørn 
Published: December 2008

AbstractThe influence of extrinsic innervation on bladder wall tension (tonus) and on intravesical pressure patterns was studied with a new cystometric procedure (Controlled Slow Cystometry, CSC) and during natural filling. After parasympathectomy, but not after sympathectomy, the basal intravesical pressure was markedly increased. At low filling rate the partial or completely denervated bladder was filled from small initial volumes without any increase in intravesical pressure. At higher rates of filling a pressure rise occcurred, and this reaction was not affected by either parasympathectomy or sympathectomy. As in the intact cat, the new pressure level was retained when the filling rate was gradually reduced. The various intravesical pressure patterns observed during filling were preserved in the partial or completely denervated organ. Thus, bladder adaptation during natural filling occurs independently of extrinsic innervation.
Fatigue and EMG of Repeated Fast Voluntary Contractions in Man
Authors: Nilsson J. , Tesch P. , Thorstensson A. 
Published: December 2008

AbstractA fatigue test consisting of repeated fast maximal contractions of the left quadriceps muscle in an isokinetic apparatus was performed by 12 healthy male subjects (19–25 yrs). EMG signals were recorded from the surface of the left vastus lateralis muscle, from which also biopsies were obtained for muscle fibre classification. Only minor changes were observed in the EMG variables despite a decrease in muscle strength performance, in terms of peak torque, work and power to about 50% of initial values after 100 contractions. The concomitantly obtained positive correlation between the increase in EMG/torque ratio and the individual percentage of fast twitch (FT) muscle fibres indicated that local factors in the muscle, primarily in the FT fibres, were causing the development of fatigue during repeated dynamic contractions with high power outputs.
Methodological Aspects of Testicular Blood Flow Measurements in Rats
Authors: Damber Jan‐Erik , Janson Per Olof 
Published: December 2008

Abstract3 techniques for the measurement of testicular blood flow in anesthetized adult rats were compared. Direct measurement of testicular venous outflow yielded values more than 3 times lower than those obtained by Xe‐133 clearance and radioactive microsphere techniques due to the surgical procedures involved in spermatic venous cannulation. There was an agreement between flow values obtained with Xe‐133 clearance (17.8 ± 3.5 ml/100 g×min) and radioactive microspheres (19.9 ± 5.5 ml/100 g×min). A homogeneous distribution of microspheres to different segments of the testis indicates that Xe‐133 clearance is an adequate technique for testicular blood flow measurements. However, for some experimental purposes the radioactive microsphere technique is more versatile than Xe‐133 clearance because of its capacity of measuring several organ flows simultaneously.
Direct Antilipolytic Effect of Acidosis in Isolated Rat Adipocytes
Authors: Hjemdahl Paul , Fredholm Bertil B. 
Published: December 2008

AbstractThe possibility that acidosis inhibits lipolysis indirectly by causing ionic shifts or by favouring the accumulation of an inhibitor has been tested in isolated fat cells. Lipolysis induced by 3 μM noradrenaline (NA) was inhibited by 40–60% and that induced by 1 mM theophylline (THEO) by about 75% when the pH was reduced to 6.6. Lipolysis induced by NA+THEO was inhibited by 20–30%. Changing the concentration of Ca++or Mg++did not alter the degree of inhibition. Reducing the K+‐ion concentration enhanced the inhibitory effect of low pH on lipolysis induced by NA or NA + THEO, whereas cyclic AMP accumulation was uninfluenced. Omitting glucose from the incubation medium caused a slight enhancement of pH‐induced inhibition of lipolysis (from 60 to 70%, p<0.01). Reducing the concentration of albumin, which binds inhibitory substances such as FFA, reduced lipolysis more at normal than at reduced pH. At high FFA/albumin ratios (5 or above) lipolysis was similar at normal and reduced pH. The antilipolytic effect of decreased pH was equally pronounced in perifused fat cells, where inhibitory substances are not allowed to accumulate. Our results suggest that the antilipolytic effect of acidosis is mainly a direct effect of the increase in H+ion concentration. The inhibitory effect of acidosis on various responses to β‐adrenoceptor stimulation may be caused by a decreased formation of cyclic AMP in turn caused directly by the decrease in pH.
Release of3H‐Acetylcholine from Isolated Guinea Pig Ileum. A Radiochemical Method for Studying the Release of the Cholinergic Neurotransmitter in the Intestine
Authors: Wikberg Jarl 
Published: December 2008

AbstractInnervated strips of longitudinal muscle of guinea pig ileum were incubated with3H‐choline in the presence of physostigmine, after which the efflux of tritiated metabolites was studied. Under resting conditions3H‐acetylcholine,3H‐choline and other tritiated metabolites were released into the incubation medium. Analysis of the kinetics of the release of the metabolites indicated that the release occurred from at least 2 different compartments. Under the unstimulated conditions used, between 72 and 78% of the radioactivity remained in a third, non‐releasable compartment. The release of3H‐acetylcholine showed spontaneous fluctuations which were positively correlated to spontaneous variations of the isometric tension of the preparation. Electrical field stimulation at low frequency (0.5 Hz) consistently increased the release of3H‐acetylcholine. The release of3H‐choline was increased only slightly or not at all by the electrical stimulation. For studying stimulation‐evoked release of3H‐acetylcholine, it is suggested that the measurement of the total quaternary amine release is of similar value to measurement of3H‐acetylcholine itself. This approach considerably simplified the method. During 5 consecutive stimulation periods of 150 pulses each, the increase in the release of total quaternary amines diminished with time. By taking into account the reduction of the stores of radioactivity in the tissue during the experiment, correction for the negative trend could be made. When the preparation was stimulated with between 30 and 3 000 pulses a close correlation was found between the increase in the release of total quaternary amines and the number of pulses delivered. The volley output of the quaternary amines was not constant, however, but diminished by increasing stimulation frequency.
Serum Testosterone Compared with Serum Zinc in Man
Authors: Hartoma R. 
Published: December 2008

AbstractSerum zinc was measured in 154 male and 95 female blood donors. Men had higher serum zinc levels than women, the difference being statistically significant (p < 0.001). The correlations between serum zinc and serum testosterone, serum zinc and serum FSH and serum zinc and serum LH were studied in 40 men aged 28–60 years and a statistically significant positive correlation was found only between serum zinc and serum testosterone in men of age 36–60 years (p < 0.005). These results do not support the theory that slight zinc deficiency primarily effects pituitary gonadotropins but indicate that it would rather act on testicular level.
Regional Brain Uptake of Noradrenaline Following Mechanical or Osmotic Opening of the Blood‐Brain Barrier
Authors: Hardebo J. E. , Edvinsson L. , Mackenzie E. T. , Owman Ch. 
Published: December 2008

AbstractThe passage of noradrenaline from the cerebrovascular circulation into the brain (vessel walls and parenchyma) was studied quantitatively and regionally by a modification of Oldendorf's technique for determination of brain uptake index. Using14C‐ethanol as the highly diffusible internal standard, the index for noradrenaline varied between 2.7 and 4.5% in different regions, confirming the poor penetration of this neurotransmitter. The barrier was impaired transiently as evidenced by Evans blue extravasation, through osmotic opening by internal carotid injection of a hyperosmolar urea solution or mechanical disruption by a short‐lasting elevation of the intracarotid hydrostatic pressure. This resulted in a 3–4‐fold increase in the passage of noradrenaline from the circulation into the brain.
K+‐Permeability of the Blood‐Brain Barrier, Investigated by Aid of a K+‐Sensitive Microelectrode
Authors: Hansen Anker Jon , Lund‐Andersen Henrik , Crone Christian 
Published: December 2008

AbstractThe K+‐permeability of the blood‐brain barrier at the capillary level was estimated from determinations of brain extracellular K+‐concentration in response to an isotonic bolus containing KC1 injected into the carotid artery. A very low permeability appeared from the fact that the extracellular K+‐concentration—measured by aid of K+‐sensitive microelectrodes—remained unchanged during the passage of the bolus. An upper limit for the blood‐brain barrier K.+‐permeability in the rat was estimated to be 2.8 7times; 10‐7 cm · s‐1.
Sustained Water Diuresis in Anesthetized Dogs: Antidiuresis in Response to Intravenous and Bilateral Intracarotid Infusion of Hyper‐Osmolar Solutions of Sodium Chloride
Authors: Bie Peter 
Published: December 2008

AbstractThe function of the suggested hypothalamic osmoreceptors was re‐examined in dogs during light chloralose anesthesia. The body weight of the dogs was increased to—and maintained at—102.0% of the initial value by i.v. infusion of a hypo‐osmolar solution of glucose and urea. During the water diuresis renal free water clearance (CH2O) remained approximately constant for more than 3 h during which infusion of physiological amounts of vasopressin (5 or 10 μU/(kg b.wt. · min)) was associated with a dose‐dependent, reversible decrease in CH2O. Infusion of hyper‐osmolar sodium chloride solution (90μmol/(kg b.wt. · min) for 60min) was performed either through a central venous catheter or through needles placed in both common carotid arteries. After an initial increase in CH2O these infusions elicited antidiuresis (negative CH2O) and increase in the rates of excretion of sodium (100‐fold) and potassium (3‐fold). Left atrial pressure and renal clearance of inulin and PAH did not change significantly. The renal effects of NaCl infusion were independent of the mode of infusion. It is concluded that the results are inconsistent with the hypothesis that the area supplied by the common carotid arteries includes an osmoreceptor which is capable of changing —within seconds—the rate of secretion of vasopressin, although they support the view that the renal excretion of water is strongly influenced by a receptor which is sensitive to osmolality or concentration of sodium. In addition it appeared that an increase of a few per cent in the concentration of sodium in plasma was associated with a substantial increase in the rate of excretion of sodium without measurable changes in central venous pressure or in glomerular filtration rate.
Electrophysiological Membrane Properties of the Frog Muscle Fibre: Effects of Detergents in the Triton Series
Authors: Rydqvist Bo 
Published: December 2008

AbstractThe effect of the nonionic detergent Triton X‐100 on the membrane properties of frog sartorius muscle fibres was studied using intracellular microelectrode technique. The effect of Triton X‐100 was compared with that of Triton X‐45 and Triton N‐101. At 40 μM Triton X‐100 had little effect on the specific membrane resistance (Rm), membrane capacitance (Cm) and the resting membrane potential (Er) while the action potential (AP) was markedly reduced. At 160 μM AP was completely abolished and Er was diminished linearily with time. The effect on the maximum rate of rise (Va) of the AP was dose‐dependent and the apparent dissociation constant (KDapp) and KD were found to be about 40 μM. The Hill coefficient was 1.6 indicating a deviation from a first order reaction. The effect of Triton X‐100 on Er may be accounted for by a reduction of the Na‐K pumping activity. The effect of Triton X‐100 on the AP is suggested to be due to a perturbation of a protein‐system either by a drug‐receptor interaction involving two or more sites, or an unspecific binding of Triton X‐100 to hydrophobic loci on the protein.
Intra‐ and Extracellular Activity of Ciliated Cells
Authors: Huberman D. , Hakansson C. H. , Mercke U. , Toremalm N. G. 
Published: December 2008

AbstractA method permitting simultaneous recording in vitro of the intracellular and extracellular (=mucociliary) activity of respiratory ciliated mucous membrane is presented. Using this method the influence of different temperature levels (20°, 30°, 40°C) upon the tracheal mucous membrane of 15 rabbits has been investigated. It is shown 1) that the extracellular (= mucociliary) activity increases with rising temperatures whereas the intracellular activity is unaffected and remains constant, indicating a temperature influence upon the respiratory tract mucus rather than a change of the intracellular “pace‐maker” mechanism; 21 that the restraining effect of the mucus decreases with rising temperatures but is still 10% of the intracellular frequency at body temperature; 3) that the presented method should be useful for future investigations concerning the effect of air‐pollution and pharmacological substances upon respiratory mucous membranes.
Regulation of the Heart of a Teleost,Gadus morhua,by Autonomic Nerves and Circulating Catecholamines
Authors: Holmgren Susanne 
Published: December 2008

AbstractThe cod heart regulation has been investigated by anatomical studies, fluorescent histochemistry, nerve stimulation and drug effects on the perfused heart and electrically paced strips. The effect on the heart of catecholamine release from the head kidney has been studied in a perfused head kidney and heart preparation. Branches of the vagi and the fused 1st and 2nd spinal nerves innervate the heart. Specifically fluorescent fibres were found in these nerve branches, in the ducts of Cuvier, all parts of the heart, bulbus arteriosus and the ventral aorta. Weakly autofluorescent ganglion cells surrounded by specifically fluorescent varicose fibres were present in the walls of the sinus venosus. Vagal stimulation caused bradycardia altered after atropine to tachycardia. Spinal nerve and sympathetic chain stimulation also induced tachycardia, as did provoked catecholamine release from the head kidney. The tachycardia could be blocked by propranolol. Atropine increased and propranolol decreased basic heart rate and contraction force. Adrenergic drugs accelerated and acetylcholine retarded the perfused heart. A positive inotropic effect was obtained with adrenergic drugs on isolated heart strips, while acetylcholine produced a negative inotropic effect on atrial but not ventricular strips. It is concluded from this study that the cod heart has an inhibitory cholinergic nerve supplyviathe vagi and an excitatory adrenergic supplyviaboth the vagi and the first spinal nerves. Sympathetically controlled release of catecholamines from the chromaffin tissue in the head kidney may also play an important role in the heart regulation.
Coacervate‐like Membrane Structures and Olfactory Transduction
Authors: Sperber G. O. 
Published: December 2008

AbstractCurrent theories concerning the olfactory transduction process are discussed. A hypothesis is formulated, according to which the olfactory receptor membrane contains regions where it has the structure of a lipid‐protein coacervate. Such structures may well occur in living cells. Such a membrane would have the ability to change its permeability in response to odorants and a sensitivity comparable to that of the sense of smell. The model also explains the fact that different receptor cells have different sensitivity patterns towards odorants. The model is consistent with the results of experiments that seek to establish the locus of odorant action.
Localization of Adrenergic Receptors in Guinea Pig Ileum and Rabbit Jejunum to Cholinergic Neurons and to Smooth Muscle Cells
Authors: Wikberg Jarl 
Published: December 2008

AbstractThe localization of adrenergic receptors mediating a relaxing action was investigated in innervated and denervated longituclinal muscle strips from guinea pig ileum and rabbit jejunum. Denervated preparations were contracted by drugs that had a direct effect on smooth muscle cells, such as acetylcholine and histamine, but not by stimuli acting on cholinergic neurons, such as electrical field stimulation or nicotine. After blockade of β‐adrenoceptors, norepinephrine relaxed the innervated guinea pig ileum contracted by electrical field stimulation, by stimulating α‐adrenoceptors. Norepinephrine in low concentrations did not relax denervated preparations contracted by agents acting directly on smooth muscle. In high concentrations, it relaxed denervated preparations by a nonadrenergic mechanism, resistant to α‐ and/or β‐receptor blockade, but which was also activated by l‐(3,4‐dihydroxyphenyl) ethanol. Phenylephrine only had a weak agonistic effect on the electrically stimulated innervated preparation and did not relax the denervated one. The denervated rabbit intestine contracted by acetylcholine was relaxed by norepinephrine and phenylephrine by stimulation of α‐adrenoceptors. In the innervated preparations both drugs were more effective in inhibiting contractions induced by electrical field stimulation or eserine than those induced by exogenous acetylcholine. Both the denervated guinea pig and rabbit intestine were relaxed by stimulation of β‐adreno‐ceptors. It is suggested that in the guinea pig ileum α‐adrenoceptors mediating relaxation are located only in cholinergic neurons, whereas in rabbit jejunum they are located both in these neurons and in the smooth muscle cells. Beta‐adrenoceptors are located in the smooth muscle cells of both organs.
Actomyosin ATPase, Myokinase, CPK and LDH in Human Fast and Slow Twitch Muscle Fibres
Authors: Thorstensson Alf , Sjödin Bertil , Tesch Per , Karlsson Jan 
Published: December 2008

AbstractThe enzyme activities of Mg2+ stimulated ATPase, creatine phosphokinase (CPK), myokinase (MK) and lactate dehydrogenase (LDH) were determined in pooled fast twitch (FT) and slow twitch (ST) human skeletal muscle fibres, dissected out from freeze‐dried muscle biopsy material. All enzymes investigated demonstrated higher activities in FT fibres. The ratio in enzyme activity between fibre types was greatest for Mg2+ stimulated ATPase (3:1) and smallest for CPK (1.3: 1). In addition, the isozyme patterns of CPK, MK and LDH were studied by means of isoelectric focusing (CPK and MK) and discelectrophoresis (LDH). A difference was observed between fibre types with respect to the isozyme distribution of MK and LDH, whereas the CPK isozyme pattern was similar in both fibre types. These results on separated human FT and ST fibres were essentially in conformity with what has earlier been indicated from experiments on mixed muscle homogenates.
Vasodilator Fibres to the Tongue in the Chorda Tympani Proper Nerve
Authors: Hellekant Göran 
Published: December 2008

AbstractElectrical stimulation of the chorda tympani proper nerve (CT) causes vasodilatation in the constant‐flow perfused tongue. It has been suggested, as an explanation for this, that the vasodilatation is the result of antidromic impulses in sensory fibres of the CT. However, after degeneration of the efferent fibres in the CT in the rat it was found that electrical stimulation of the CT caused no vasodilatation. Since, by all criteria available, the sensory fibres remained, the result indicates that antidromic impulses could not be the cause of the vasodilatation observed in tongues with intact nerve supply. Further, since there are no glands in the part of the tongue innervated by the CT and the circulation of the large salivary glands is separate from the tongue in the rat, it is concluded that the vasodilatation was not a secondary effect of glandular activity, but was caused by vasodilator fibres in the CT.
Blood Pressure and Heart Rate Regulating Capacity of the Carotid Sinus during Changes in Blood Volume Distribution in Man
Authors: Bevegård Sture , Castenfors Jan , Erik Lindblad Lars , Tranesjö Jussi 
Published: December 2008

AbstractThe influence of changes in blood volume distribution on the carotid baroreflex was studied in 18 subjects. Blood volume distribution was changed by varying the pressure around the lower body above and below ambient, thereby varying the amount of blood pooled in this region and exerting a secondary influence on the central blood volume. The carotid arterial stretch receptors were stimulated by varying the pressure in an air‐tight box enclosing the neck. To obtain a standardized carotid sinus stimulus (SCS) the pressure in the box was varied sinusoidally between ‐10 and ˜ 40 mmHg with a fixed frequency of 0.03 Hz. The effects on heart rate and blood pressure were assessed by harmonic analysis performed off‐line on a digital computer. During lower body negative pressure of –40 mmHg (LBNP ‐ 40), i.e. during a procedure known to reduce the central blood volume, SCS induced an augmented effect on the blood pressure regulating capacity but not on the heart rate response. Expressing the blood pressure regulating capacity as peak‐to‐peak changes in systolic arterial pressure, the response during LBNP 40 mmHg was almost twice the control value. The opposite stimulus–lower body positive pressure–influenced the SCS‐induced effects only slightly but on the average a minor reduction in both blood pressure and heart rate regulating capacity was found compared with the control condition, though the difference did not reach significant levels.The results support the hypothesis that changes in blood volume distribution modify the function of the carotid baroreflex, possibly via intrathoracic receptors sensitive to changes in central blood volume and/or central venous pressure.
Effect of Sodium Pentobarbital on the Apparent Turnover of Acetylcholine in Different Brain Regions
Authors: Nordberg Agneta , Sundwall Anders 
Published: December 2008

AbstractThe turnover rate of acetylcholine (ACh) was measured in six different brain regions in the mouse following pulse injection of radioactive choline (Ch) and killing of the animals by microwave irradiation of the head (0.25 s, 5 kW). The time course of the change in3H‐ACh/3H‐Ch ratio was linear 0–60 s in all brain regions after administration of3H‐Ch. Plots of the specific radioactivities (SA) of ACh and Ch versus time indicate a precursor‐product relationship in all brain regions except the cerebellum both in control and sodium pentobarbital anesthesized animals. The turnover was highest in the striatum (55 nmol g‐1min‐I), while in the cortex and hippocampus this value was approximately half (27 and 21 nmol‐g‐1‐min‐1). In the midbrain and medulla oblongata the turnover rates were only 11 and 10 nmol gr‐1min‐1. Sodium pentobarbital anesthesia reduced specifically the turnover in the cortex and hippocampus to about 60 to 70 per cent.