bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gastric Clearance of Gastrin during Acid Secretory Responses to Vagal Activation and its Effect on Peripheral Gastrin Levels A Study on Anesthetized Cats
Authors: Uvnäs‐Wallensten K. , Uvnäs B. 
Published: December 2008

AbstractGastrin release and gastric acid secretion were induced by electrical stimulation of the vagi in anesthetized cats. No correlation was found between the peripheral gastrin levels and the magnitudes of the concomitant secretory responses. In experiments in which a high rate of secretion was induced the peripheral gastrin levels were found to be unchanged or at most slightly elevated, whereas the levels were sometimes substantially elevated in animals in which there was little or no acid secretory response.An arterio‐venous difference in gastrin levels was detected in the corpus blood during periods of gastric secretion. This clearance of gastrin (104–540 pg/min) was large enough to influence the peripheral gastrin levels. The mechanism behind and the significance of the gastric clearance of gastrin is discussed.
Liver and Heart Mitochondrial Succinate Dehydrogenase Activity of Newborn Rats in Anoxic Hypoxia and Starvation
Authors: Kinnula Vuokko L. , Juujärvi Kyösti 
Published: December 2008

AbstractSuccinate dehydrogenase activity was determined in the liver and heart of newborn rats after 3 and 48 hours' exposure to anoxic hypoxia (10% O2) and after 48 hours' starvation. Control determinations were made on newborn animals of corresponding ages, full term foetuses (21 days), infantile (1 and 2 weeks) and full grown animals. Hypoxia for 3 h had no influence on succinate dehydrogenase activity at all in either the heart or liver mitochondria of the newborn animals. After 48 h no difference was observed in the liver between the hypoxic animals and the starved controls of the same age, though starvation itself had resulted in a significant increase in activity, as much as 42%. When liver mitochondrial succinate dehydrogenase in normal mitochondria was activated by preincubation mitochondria with the substrate, the activity increase obtained was greater than that resulting from starvation. The increase in activity in the heart of the hypoxic or starved animals was not significant (< 10%).
Vagal Influence on Serotonin Concentration in Enterochromaffin Cells in the Cat
Authors: Ahlman H. , Dahlström A. , Kewenter J. , Lundberg J. 
Published: December 2008

AbstractThe intracellular concentrations of 5‐HT in enterochromaffin cells of the jejunum, midgut and ileum of the cat have been estimated by a cytofluorimetric method before and after various periods of peripheral vagal nerve stimulation. The fluorescence intensities in randomized cell samples were measured photometrically after a standard illumination time before and after nerve stimulation. A significant decrease in 5‐HT concentration in the enterochromaffin cells all through the small intestine could be demonstrated, which is in support of the hypothesis of a neurogenic release of 5‐HT from enterochromaffin cells, possibly caused by vagal adrenergic fibres.
Prostaglandins, a Link between Renal Hydro‐ and Hemodynamic in Dogs
Authors: Olsen Uffe Bang , Magnussen Magnus Pauli , Eilertsen Eva 
Published: December 2008

AbstractAn increase of the intrarenal pressure to 40 mmHg induced by ureteral constriction or by kidney compression is shown to be followed by increased renal blood flow in anesthetized dogs. This hyperemia is probably the result of enhanced intrarenal prostaglandin activity since it is followed by increased urinary prostaglandin E excretion and is abolished by indomethacin pretreatment. The increase of renal blood flow seems to be due to dilation of the afferent arteriole in order to maintain the filtration pressure. The glomerular filtration rate is thus severely depressed in indomethacin pretreated dogs. Urine and electrolyte excretion is comparably reduced during elevated intrarenal pressure in non‐pretreated and in indomethacin pretreated dogs, which suggests that factors other than glomerular filtration rate are involved. Urine osmolarity is positively correlated with renal blood flow, and urine osmolarity increases during elevated intrarenal pressure in non pretreated dogs, whilst urine osmolarity remains unchanged in dogs pretreated with indomethacin.
Effect of Chronic Sympathetic Denervation upon Local Regulation of Blood Flow in Human Subcutaneous Tissue
Authors: Henriksen O. 
Published: December 2008

AbstractThe effect of chronic sympathetic denervation upon the vasoconstrictor response to an increase of vascular transmural pressure in human subcutaneous adipose tissue was investigated in 6 patients suffering from manual hyperhidrosis. Changes in transmural pressure were obtained either by postural changes of a forearm or by venous stasis of 30 mmHg. Blood flow was measured in the distal part of the forearm or crus by means of the local133Xenon washout technique. 2 patients were studied before and after sympathectomy. When the area under study was lowered about 40 cm below the jugular notch, blood flow decreased about 50 per cent preoperatively, about 30 per cent 24 h after the operation, but remained constant 4 days after or later. Similar results were obtained during venous stasis. Hence about 4 days after sympathectomy, the vasoconstrictor response to an increase in vascular transmural pressure was abolished. In 3 chronically sympathectomized patients blood flow remained constant in the denervated limb, but decreased significantly in the control limb. In another patient studied 580 days after surgery blood flow remained constant during lowering of the denervated forearm as well as during venous stasis.These findings might indicate that the vasoconstrictor response to an increase in vascular transmural pressure in human subcutaneous adipose tissue is due to a local nervous mechanism involving symphathetic adrenergic nerves, but a myogenic mechanism cannot be definitively excluded.
Local Nervous Mechanism in Regulation of Blood Flow in Human Subcutaneous Tissue
Authors: Henriksen Ole 
Published: December 2008

AbstractThe effect of local venous stasis upon blood flow in human subcutaneous adipose tissue on the distal part of the forearm was investigated in three healthy subjects and two chronically sympathectomized patients suffering from manual hyperhidrosis. The area under study was separated into two parts by means of a lead shield exerting a pressure of about 360 mmHg on the skin. The effect of venous stasis of about 40 mmHg on one side of the shield upon blood flow measured simultaneously on both sides of the shield by the local 133Xenon washout technique was investigated. During venous stasis on one side of the shield, blood flow decreased about 40 per cent on both sides. The vasoconstrictor impulse could be transmitted over a distance of about 1–2 cm. The phenomenon was unaffected by nerve blockade induced 3 cm proximally, medially, and laterally to the area by infiltration the skin with lidocaine. Thus a vasoconstrictor impulse could be transmitted from the side of stasis to the non stasis side of the lead shield. The transmission was not affected by phentolamine but was blocked by lidocaine and chronic sympathetic denervation.The vasoconstrictor impulse elicited during venous stasis is therefore most likely transmitted by means of a local nervous mechanism involving sympathetic adrenergic vasoconstrictor fibres.
Quantitative Measures of Enzyme Activities in Type I and Type II Muscle Fibres of Man after Training
Authors: Henriksson Jan , Reitman James S. 
Published: December 2008

AbstractThe effect of 7 to 8 weeks of physical training on oxidative and glycolytic enzyme activities in the 2 major fibre types of human quadriceps femoris muscle has been investigated. 2 groups of 4 and 5 subjects respectively were trained at the same total work‐load on a bicycle ergometer 3 days per week using interval exercise with maximal intensity (I.T.) or continuous exercise with submaximal intensity (C.T.). Succinate dehydrogenase (SDH) and phosphofructokinase (PFK) activities were determined on crude homogenates of muscle biopsy samples and on pools of type I and type II fibres dissected from freeze‐dried samples taken before and after training. Crude homogenate SDH activity increased to the same extent in both groups, average increases were 27.5% (I.T.) and 22% (C.T.), respectively. Only type I‐SDH increased in the C.T. group (p<0.01), the average increase being 32%. On the other hand only type II‐SDH increased in the I.T. group (p<0.01), with an average increase of 49%. No changes in PFK activity could be detected. The results of the present study emphasize the great adaptability in oxidative potential of both the two major human skeletal muscle fibre types and further that this adaptation seems to be related to the pattern of fibre recruitment during exercise.
Diffusion of Sodium in Axoplasm of Myelinated Nerve Fibre. Potential Clamp Analysis
Authors: ÅRhem Peter 
Published: December 2008

AbstractThe diffusion of sodium and lithium in the axoplasm of myelinated fibres of Xenopus laevis was investigated. The sodium current associated with pulse steps was measured and the internal sodium concentration was calculated from these measurements with the constant field equation. The internal sodium concentration was increased either (i) by massive pulse trains or (ii) by applying a sodium containing solution to a cut end of the fibre. The time course of the concentration change was measured. Equations were solved numerically for a model axon where sodium diffused freely in the axoplasm. It was found that the experimental results were satisfactorily predicted by this model axon. The calculated diffusion coefficient for sodium in axoplasm seemed to be somewhat lower than that in water. Similar experiments were performed with lithium. These results agreed with the predictions based on unrestricted diffusion in the axoplasm. It is concluded that no major diffusion barriers were present within the axoplasm.
Local Reflex in Microcirculation in Human Subcutaneous Tissue
Authors: Henriksen Ole 
Published: December 2008

AbstractThe effect of changes in transmural pressure in the vessels of the extremities on blood flow in subcutaneous adipose tissue was investigated in three healthy subjects. Changes in transmural pressure were obtained either by postural changes of a limb, by locally induced subatmospheric pressure, or by venous stasis. Blood flow in subcutaneous tissue was measured 10 cm distal to the fibular head and at the lateral malleolus in the leg, or in the distal part of the forearm by the local133Xenon washout technique. When transmural pressure increased 25 mmHg or more, blood flow decreased about 50 per cent due to an increase in vascular resistance, but remained constant in the contralateral side. This vasoconstrictor response to increase in transmural pressure could be blocked by infiltrating the area under study with phentolamine or lidocaine or by induced counterpressure. In these cases blood flow remained constant. The findings indicate that the vasoconstrictor response to increase in transmural pressure of 25 mmHg or more is due to a local nervous mechanism involving adrenergic nerves. The receptors are presumably stretch receptors placed in the small veins. The effector site is probably the arterioles. When the vasoconstrictor response is blocked, autoregulation of blood flow in subcutaneous tissue, i.e. maintenance of constant blood flow during changes in perfusion pressure head or during changes in transmural pressure, is revealed. The vasoconstrictor response to increase in transmural pressure will counteract an increase in transmural pressure in the exchange vessels and thereby act as an edema protecting factor.
Effect of Glucagon on Cyclic AMP, Albumin Metabolism and Incorporation of 14C‐Leucine into Proteins in Isolated Parenchymal Rat Liver Cells
Authors: Dich J. , Gluud C. N. 
Published: December 2008

AbstractParenchymal rat liver cells were isolated by the collagenase method and incubated in Krebs‐Henseleit buffer containing 0.5% gelatin. The basal level of cyclic AMP in isolated cells was 0.52 nmol per g liver wet wt. Glucagon (10‐10‐ 10‐6 M) caused a significant increase in the level of cyclic AMP. Maximum levels were obtained 2–15 min after addition of glucagon. Repeated administration of glucagon caused a new increase in cyclic AMP, but the response was lesser than after the first addition of glucagon, indicating refractoriness to glucagon. The rate of albumin secretion was 4.6 μg/min per g liver wet wt. This is about the rate found in the perfused liver. Glucagon (10‐8‐ 10‐6 M) inhibited albumin secretion and the incorporation of 14C‐leucine into albumin, into total proteins in the medium and into total proteins in the cell suspension. The effect of glucagon on albumin secretion is compatible with an effect on the rate of synthesis. A positive correlation existed between the maximal level of cyclic AMP after glucagon administration and the inhibition of both albumin secretion and the incorporation of 14C‐leucine.
Hyperglycemic and Hyperosmolar Responses to Graded Hemorrhage
Authors: Järhult Johannes , Holmberg Jan , Lundvall Jan , Mellander Stefan 
Published: December 2008

AbstractChanges of the arterial plasma osmolality and of the glucose concentration were followed during a 30 min period of graded hemorrhagic hypotension (80, 50, and 30 mmHg) in the cat. Bleeding evoked a significant plasma hyperosmolality at all three hypotension levels and the responses were quantitatively related to the degree of hypotension. An approximate steady state increase in the arterial plasma osmolality was reached about 20 min after the start of the bleeding and it then averaged 8, 20, and 25 mOsm/kg H2O at 80, 50, and 30 mmHg, respectively. Bleeding also evoked an increase in the plasma glucose concentration, which almost entirely accounted for the observed hyperosmolality, especially at 80 and 50 mmHg. In late stages of hypotension at 30 mmHg, elevated plasma lactate and potassium concentrations contributed to the overall hyperosmolality. — Previous hemorrhagic hypotension experiments at 50 mmHg (Järhult 1975 b) have shown that hyperosmolality serves as an important regulator of the plasma and extracellular fluid volumes during bleeding. The present results indicate that such an osmolar compensatory mechanism is operating over wide ranges of hemorrhagic hypotension.
The Dependence of Tension Relaxation in Skeletal Muscle on the Number of Sarcomeres in Series
Authors: Bartels Else M. , Jensen P. , Sten‐Knudsen O. 
Published: December 2008

AbstractMulieri (1972) has reported that the depth of the latency relaxation, tension relaxation, changes only insignificantly when about half of a fibre bundle is wound tightly around a small glass rod. From this observation he concludes that the tension relaxation is not correlated with the number of sarcomeres in series in a frog muscle fibre. The dependency of the tension relaxation on the number of sarcomeres in series has been reinvestigated using both Mulieri's method and other independent methods. When Mulieri's experimental procedure was repeated, his result was reproduced. In the other methods used the tension relaxation was found to be proportional to the number of sarcomeres in series which were activated initially. This result was also obtained by introducing a slight modification to the procedure used by Mulieri. The results could equally well be understood if the latency relaxation was caused by a definite elongation rather than an increase in compliance of the fibre.
Factors Influencing the Insulin Space in Cerebral Cortex Slices from Adult and 7‐Day‐Old Rats
Authors: Laakso M.‐L. , Oja S. S. 
Published: December 2008

AbstractThe inulin spaces and swelling of brain cortex slices from adult and 7‐day‐old rats were measured under differing experimental conditions. At 37°C inulin penetrated into larger compartments than at 0°C in both age groups. At 37°C the inulin space increased with decreasing concentration of inulin in the medium. At 0°C the inulin space did not depend on the inulin concentration. The swelling of the slices at 37°C diminished with increasing concentrations of inulin. Anaerobic conditions, 0.2, and 1.0 mmol/1 sodium cyanide and 0.1 mmol/1 dinitrophenol reduced the inulin space and caused increased swelling of the slices. 1.0 mmol/1 sodium iodoacetate was ineffective. In anaerobic conditions the inulin space did not change significantly as a function of the inulin concentration. A serious disadvantage of the inulin space as an indicator of extracellular space is that its size depends on the inulin concentration used. The inulin itself may influence the size of the space to be measured. Inulin also in osmotically inactive concentrations considerably reduces the swelling of brain cortex slices.
Electric Activity of the Rat Myometrium In Vivo during the Estrous Cycle
Authors: Talo A. , Karri A. E. 
Published: December 2008

AbstractElectric activity of the uterus was recorded by 6 chronically implanted wire electrodes in 17 unrestrained 5‐day cycling rats. Results obtained during 196 h of recording revealed consistent changes in frequency, amplitude, temporal pattern and in direction and distance of propagation of electric activity. In estrus, bursts were short and of variable amplitude and frequency, while in metestrus bursts had high amplitude, longer duration and regular frequency. The activity decreased from metestrus to the first diestrous day and still more to the second diestrous day. In diestrus and proestrus long bursts appeared once or twice within an hour. In proestrus the morning level of activity was still low, but high at night, when it resembled the activity in estrus. Electric activity spread in both directions but with a higher frequency in the cervical direction in all phases of the cycle. Cervical electric activity appeared in synchrony with that of the uterine body and did not differ from it in type.
Heart Volume and Myocardial Connective Tissue during Development and Regression of Thyroxine‐Induced Cardiac Hypertrophy in Rats
Authors: EDGREN, JOHAN , LINDY SEPPO , Knorring Johan Von , Lindy Seppo , Turto Heikki 
Published: December 2008

AbstractTo determine whether development and regression of cardiac hypertrophy are accompanied by changes in heart volume and to learn whether a change in heart volume is associated with changes in the myocardial connective tissue, cardiac hypertrophy was induced in rats by administration of thyroxine. Rats were given L‐thyroxine for 4 weeks. Heart volume was estimated radiologically in vivo at the start of the experiment and at 1‐ or 2‐week intervals for 7 weeks. At each of these stages a number of rats were killed, their hearts were weighed and determinations were made of the myocardial contents of DNA, of collagen measured as hydroxyproline, and of glycosaminoglycans, measured as uronic acid. After thyroxine treatment the ratio of left heart ventricle weight to body weight and of heart volume to body weight rose significantly. The increase in heart weight was greater than the increase in heart volume. At the same time, there was a significant decrease in the concentration of hydroxyproline. After discontinuation of thyroxine treatment heart volume, heart weight and the concentration of myocardial collagen returned to normal within 2 weeks. However, the total amount of myocardial collagen was still less than normal at 2 weeks. The results suggest that the decrease in the amount of myocardial collagen associated with thyroxine‐induced cardiac hypertrophy—because it results in a weakening of the supporting properties of the myocardial connective tissue framework— might contribute to a slight increase in in vivo heart volume.
The Potassium Concentration in Cerebrospinal Fluid in Young and Adult Rats Following Complete Brain Ischemia. Effects of Pretreatment with Hypoxia
Authors: Hansen Anker Jon 
Published: December 2008

AbstractThe potassium concentration in the cisternal cerebrospinal fluid (CSF) was measured following brain ischemia in rats of different ages which had been kept at normoxia or pretreated with hypoxia (PIO2= 70 mmHg) for 24 h. In all age groups the potassium concentration rose following ischemia. The rate of rise was relatively slow in the 4‐day rat and faster in 16‐ and 24‐day rats; beyond this age the rate of rise became slower. Pretreatment with hypoxia significantly diminished the rate of rise in CSF potassium in 4‐ and 8‐day rats, while no effect was observed in the older age groups. It is suggested that the rate of rise in CSF potassium is inversely correlated with the capacity of surviving a period of oxygen deprivation.
On the Formation and Effects of Thromboxane A2 in Human Platelets
Authors: Svensson J. , Hamberg M. , Samuelsson B. 
Published: December 2008

AbstractIncubation of arachidonic acid and prostaglandin G2 with a suspension of human platelets led to formation of an unstable (t1/2 41 ± 7 s) compound, thromboxane A2 Thromboxane A2 induced irreversible aggregation of washed platelets and of platelets in platelet‐rich plasma and caused release of serotonin and ADP from platelets in platelet‐rich plasma.
Some Physical Properties of the Pulmonary Arterial Bed Deduced from Pulsatile Arterial Flow and Pressure
Authors: Piene Hroar 
Published: December 2008

AbstractThis study aimed to quantify changes of vascular compliance and resistance of the proximal and the peripheral pulmonary arterial vessels when vascular smooth muscle was stimulated. These above vascular characteristics were derived from registrations of pulsatile pressure and flow in the pulmonary artery (PA). An in situ cat lung preparation was used, with the right heart by‐passed by a pulsatile blood pump. Vascular input impedance was derived from PA pulsatile pressure and flow recordings, and impedance characteristics were used for calculation of the variables of a simple lumped analog representation of the arterial bed. PA smooth muscle was stimulated by infusions of collagen suspension, by general hypoxia and by nor‐adrenaline injections. Collagen caused 40% reduction of vascular compliance (C), no changes in proximal arterial resistance (Rl) and 18076 increase in peripheral vascular resistance (R2). Hypoxia caused 5096 reduced C, 20% increased R1 and 70% increased R2. Noradrenaline caused 20:6 reduced C and 30 % increased R1 and R2. These results, together with results derived from simulation of the observed impedance changes in a computer model of the lung arterial bed, indicated that collagen infusion elicited contraction of small and medium‐sized arteries, with increased arterial volume as result of increased distending pressure. Hypoxia and noradrenaline, seemed both to cause contraction of the total arterial bed. This effect being most pronounced during hypoxia.
Fatiguability and Fibre Composition of Human Skeletal Muscle
Authors: Thorstensson Alf , Karlsson Jan 
Published: December 2008

AbstractThe fatiguability of the quadriceps muscle was investigated in 10 male subjects (25–40 yrs), with inter‐individual differences in fibre composition of their vastus lateralis muscles (range 25–65 % fast twitch, FT, muscle fibres). Fatiguability was assessed as the decline in maximal force (in % of initial values) with 50 repeated isokinetic knee‐extensions at fast angular velocity (3.14 radis). Each contraction lasted 0.5 s and the rest periods were about 0.7 s. Every subject was tested on two occasions and the standard deviation for a single determination of fatiguability was 1.47:., The decline in force after 50 contractions was on the average about 45%. The individual values varied, however, and a linear correlation was present between fatiguability and % FT fibres (r = 0.86, p–.0.01). It was concluded that development of fatigue in human skeletal muscle performing repeated fast dynamic contractions with maximal effort was most marked in muscles with a high proportion FT fibres. This finding was in conformity with earlier results from animal skeletal muscle preparations.