bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relationship between Blood Pressure and Diameter of Ascending Aorta in Normal and Hypertensive Rabbits
Authors: Aars Harald 
Published: December 2008

AbstractEarlier studies of strips from rabbit aorta suggest that hypertensive resetting of aortic baro‐receptor activity (Aars 1968a) might be due to hypertensive changes of the aortic wall in the receptor area (Aars 1968b). In order to obtain information under conditions equal to the demonstration of resetting, the relationship between blood pressure and diameter of ascending aorta has been examined in 11 normal rabbits and five rabbits with renal hypertension of about one week's duration. The transit time of ultrasonic pulses between two crystals glued to aorta was used to measure the aortic diameter. Below 70–100 mm Hg, aortic distensibility was equal in hypertensive and normal rabbits. The normal aorta became markedly stiffer at higher pressures, whereas in hypertensive rabbits the relationship between pressure and diameter remained linear to near hypertensive control pressures. This indicates that at pressures below approximately 130 mm Hg, stretching of aortic wall elements‐and presumably stimulus to baroreceptor activity‐was less in hypertensive than in normal animals. The curves for dynamic elastic modulus were also shifted to higher pressures, illustrating the ability of the aortic wall to maintain almost the same distensibility at control pressures in hypertensive and normotensive conditions. The rate of change of pulsatory diameter variations was closely related to their amplitude, and this relationship did not differ significantly in normal and hypertensive rabbits.
Studies on the Distribution and Elimination of [3H8] Pyridoxine in Mice
Authors: Dahlkvist Giesela , Lindstedt Sven , Tiselius Hans‐Göran 
Published: December 2008

Abstract[3H8] Pyridoxine has been administered by i.v. injection to mice, and the concentration of isotope has been determined in different tissues up to 30 days after the administration. An initial high uptake was found in all tissues except brain. The concentration decreased rapidly during the first day after administration and then at a slow rate. The decrease of isotope concentration was more rapid in liver than in muscle or carcass. The elimination of the vitamin from the body reservoir was estimated to be 7.9 per cent per day from day 1 to 30 compared to 6.5 per cent per day as calculated from the rate of excretion of isotope in the urine. One week after the administration of the isotope the concentration was approximately the same in heart, skeletal muscle, brain and kidney, and 20 % higher in liver. Between day 7 and 30 after the administration [3H8] pyridoxine 75% of the recovered isotope was found in carcass, 10–15% in liver and the remainder in other tissues.
Electrical Stimulation of a Human Ventrolateral‐Subventrolateral Thalamic Target Area
Authors: Johansson Gunnar G. 
Published: December 2008

AbstractA method is described for electrical stimulation of human subcortical brain structures. The necessity is shown for monitoring both the voltage across and also the current through the stimulated brain tissue, as well as the duration of the stimuli applied. Stimulus trains of constant composition were repeatedly applied to a ventrolateral‐subventrolateral thalamic target area in 12 alert patients undergoing stereotaxic thalamotomy. Stimulation at the clinical threshold resulted in motor and “sensory” responses projected to contralateral parts of the body. In spite of small temporary variations, no distinct change of response from one stimulus train to the next in the same patient could be detected when the stimulation was applied at intervals of either 15, 30, or 60 sec. The current thresholds, on the other hand, showed a tendency to decrease if the intervals were less than 60 sec. The stimulation method and the results of stimulation are discussed.
Electrical Stimulation of a Human Ventrolateral‐Subventrolateral Thalamic Target Area
Authors: Johansson Gunnar G. 
Published: December 2008

AbstractA ventrolateral‐subventrolateral thalamic target area was electrically stimulated in connection with stereotaxic neurosurgery in 16 alert patients with Parkinson's disease, in 4 patients with hereditary intention tremor and in 1 patient with choreoathetosis. The stimulations were performed as a part of a larger investigation concerned with the effect of altering stimulus parameters on the clinical responses evoked. Unidirectional square wave pulses with a constant pulse duration and repetition frequencies ranging from 1 to 200 pulses per second were applied. The stimulation was kept at the threshold for clinical responses by balancing the different repetition frequencies with the peak current. The stimulation elicited motor and “sensory” responses. The character of the responses depended on the pulse repetition frequency used. The projected localization of the responses in the body remained unchanged. The peak current‐pulse repetition frequency relationship at the threshold for evoking clinical responses is shown. The results are discussed.
Unit Responses in the Cochlear Nucleus of the Rat to Pure Tones
Authors: Moller Aage R. 
Published: December 2008

AbstractIn a study of the response of single units in the cochlear nucleus of the white rat it was found that all the units which responded to pure tones showed a selectivity with regard to tone frequency. Responses were obtained in the tone frequency range from 200 to 34,000 Hz. Most of the units responded to pure tones with a sustained train of discharges. The threshold in these units was found to rise abruptly when the tone frequency was increased above that of the unit's characteristic frequency (CF). A much more gradual increase in threshold was noted when the tone frequency was decreased below the unit's CF. The slope of the high frequency part of the tuning curves varied between 0 and 50 Hz per dB increase in threshold, when measured 20—30 dB above the unit's threshold at its characteristic frequency. The slope measured in that way showed no apparent dependence of on the CF of the units. Many units with a high CF had tuning curves with a second peak located at a lower frequency. A few units had almost symmetrical tuning curves with a slope of the same order of magnitude as that recorded for the low frequency part of the common type units. The maximal obtainable firing rate of common type units was found to decrease rapidly when the frequency of the stimulus tone was increased above the unit's CF. Conversely the maximal discharge rate was almost constant for tones below the unit's CF. Iso‐rate functions based on stimulus response curves, were found to be similar to tuning curves when a discharge rate of about 20 per cent about the unit's spontaneous rate was used as a criterion of response.
The Secretion of Adrenaline and Noradrenaline in 20° C and 3° C Acclimated Rats Injured by Limb Ischemia
Authors: Stoner H. B. , Westerholm Barbro 
Published: December 2008

AbstractThe effects of hind‐limb ischemia on the concentrations of adrenaline and noradrenaline in the adrenals, heart and spleen, on the excretion of these compounds and their 3‐0‐methylated metabolites in the urine and on the uptake of (°)‐noradrenaline‐7‐3H by the adrenals, kidneys. spleen and heart have been studied in 20° C and 3° C acclimated rats at an environmental temperature of 20° C. The adrenals of uninjured 3° C acclimated rats contained more adrenaline and noradrenaline than those from 20° C acclimated rats. In a 20° C environment both types of rat excreted the same amounts of these compounds. Hind‐limb ischemia increased the rate of secretion of adrenaline and noradrenaline since the adrenal contents of these compounds were reduced, their excretion and that of two of their metabolites was increased and tissue uptake was not reduced. The response was the same in 20° C and 3° C acclimated rats after a 4 hr period of bilateral hind‐limb ischemia. According to the assay methods used adrenaline secretion preceded that of noradrenaline and the secretion of both continued for up to 26 hrs after the injury. The possible factors in the injury leading to the increase in catecholamine secretion are discussed and also the relation between these changes and some of the biochemical sequelae of limb ischemia.
Effect of Reserpine on Accommodation and Pupil Diameter in Monkeys (Macaca irus)
Authors: Töurnqvist Göuran 
Published: December 2008

AbstractPupil diameter and refractive state were measured in cynomolgus monkeys under pentobarbital before and after i.m. administration of reserpine, 2 and 5 mg/kg. Reserpine was found to cause only a small miotic response and no accommodation at all.
Intercostal‐to‐Phrenic Reflexes in the Spinal Cat
Authors: Decima Emilio E. , Euler Curt von , Thoden Uwe 
Published: December 2008

AbstractThe diaphragm, which previously has been shown to contain relatively few proprioceptors and to lack autogenetic facilitation, was found to be under reflex control from intercostal afferents. Electrical stimulation of the intercostal nerves of the lowest thoracic segments elicited a polysynaptic reflex excitation of phrenic motoneurones followed by a depression of ‘spontaneous’ phrenic motor activity. No phrenic responses were elicited from the upper thoracic segments. Increased phrenic activity was also elicited by mechanical stimulation of the trunk wall; the receptive area of these effects was similarly limited to the region of the insertion of the diphragm. Alike reflex effects were obtained from both the internal and the external intercostal nerves. In the internal nerve both group Ib and II afferents were found to contribute to the reflex whereas in the external nerve it was mainly the secondary muscle spindle endings which gave rise to the response. In contrast to the intercostal‐to‐intercostal reflexes cutaneous afferents proved to be without effect in the intercostal‐to‐phrenic reflex.
Excitability of Phrenic Motoneurones to Afferent Input from Lower Intercostal Nerves in the Spinal Cat
Authors: Decima Emilio E. , Euler Curt von 
Published: December 2008

AbstractThe reflex connections between the lower intercostal segments and the phrenic motor pool, described in a preceding paper, has been studied further. It was found that the diaphragm on contraction could exert enough mechanical force on the lower part of the rib cage to provoke a reflex discharge in the phrenic motoneurones. The intercostal‐to‐phrenic reflex arch thus constitutes a link in a loop for self‐excitation of the phrenic nucleus which may make up for its lack of autogenetic facilitation. Up to five synchronized reverberating phrenic volleys could be recorded in response to a single diaphragmatic jerk. These were abolished by paralyzing doses of gallamine. Conduction times and excitability cycles for the loop have been studied. Examination of reflex firing probality for phrenic motoneurones has revealed considerable individual differencies in their responsiveness to each of the three afferent input parameters: a) nerve stimulated, b) strength and c) frequency of stimulation. The order of reflex recruitment of phrenic motoneurones followed the same order as found for their respiratory engagement: small spikes always appeared earlier than bigger spikes.
Possible Relation between the Degree of Cardiac Adrenergic Innervation and the Resistance to Hypothermic Ventricular Fibrillation in Young Cats
Authors: Nielsen Kai C. 
Published: December 2008

AbstractKittens weighing 0.5 to 1 kg, corresponding to an age of 5 to 10 weeks, were subjected to immersion hypothermia to 17.4–16.2oC rectal temperature. Blood pressure, ECG, respiration, and rectal temperature were continuously recorded. Metaraminol was administered intermittently to maintain an adequate blood pressure at lower temperatures, and the animals were respirated mechanically when necessary. Only 1 out of 12 kittens developed ventricular fibrillation; the remaining animals could be re‐warmed without major complications. Under similar conditions, adult animals have previously been found to develop ventricular fibrillation constantly. Fluorescence microscopy revealed a low degree of development of cardiac adrenergic nerves compared with adult animals, in agreement with a lower concentration of cardiac noradrenaline. The possibility is discussed that the not yet fully developed adrenergic innervation of the heart in young animals may account for the higher resistance to reduction of the body temperature as compared with adult animals.
Control of Spontaneous Ventricular Fibrillation during Induced Hypothermia in Cats by Acute Cardiac Sympathectomy
Authors: Nielsen Kai C. , Owman Christer 
Published: December 2008

Abstract17 adult cats were subjected to cardiac sympathectomy under nembutal anesthesia by bilateral excision of the cervical sympathetic chains between and including the superior cervical and stellate ganglia. Immediately after operation, the anesthetized animals were cooled by submersion in an ice‐water bath. Blood pressure, ECG, rectal temperature and respiration were continuously observed. Angiotensin was administered intermittently to maintain the blood pressure at an adequate level at the lower body temperatures. Artificial respiration was applied when indicated. Under these conditions, only 2 out of 17 denervated animals died in ventricular fibrillation, at 23 and 18.4oC rectal temperature. The remaining animals were cooled to 17.7–15oC and subsequently re‐warmed to normothermia without complications. All of 17 unoperated control animals subjected to hypothermia in the same way developed ventricular fibrillation. Cardiac noradrenaline determined fluorimetrically at the end of the experiments did not differ significantly between the two experimental groups. The results of the present and earlier investigations indicate that hypothermia activates the sympathetic system through a central mechanism and that the cardiac sympathetic nerves represent an important factor for the spontaneous development of ventricular fibrillation, a characteristic complication of induced deep hypothermia in homeothermic mammals.
Effects of Epsilon Aminocaproic Acid (EACA) and Trasylol on Thromboplastin‐Induced Intravascular Coagulation, Studied in Dogs with Iodine‐Labelled Fibrinogen
Authors: Nordström Sam , Zetterqvist Eric 
Published: December 2008

AbstractThe elimination of iodine‐labelled fibrinogen was followed in 3 groups of dogs after: 1. thromboplastin infusion, 2. simultaneous infusions of thromboplastin and epsilon aminocaproic acid (EACA), and 3. simultaneous infusions of thromboplastin and Trasylol. Platelet count, fibrinogen concentration, radioactivity in plasma and in fibrinogen as well as hematocrit were determined. Thromboplastin caused changes of the same type as those previously obtained with thrombin, indicating the development of a fibrinolytic process, secondary to intravascular coagulation. The secondary changes were effectively blocked by pretreatment with EACA and Trasylol. The incidence of and mortality in thromboembolism suggest some anticoagulant effect of Trasylol. The antifibrinolytic activity of Trasylol is much stronger than the anticoagulant one. EACA too, seems to give some protection against thromboplastin‐induced coagulation.
Hypoxia and Pulmonary Vascular Resistance. The Relative Effects of Pulmonary Arterial and Alveolar PO2
Authors: Hauge Anton 
Published: December 2008

AbstractThe relative effects of pulmonary arterial and alveolar P02 on pulmonary vascular resistance (PVR) have been studied in isolated and ventilated rat lung preparations. The experimental arrangement included two such preparations perfused in series with homologuous blood. Pulmonary arterial hypoxemia (Po2 28–44 mm Hg) without alveolar hypoxia did not elicit vasoconstrictor response. High pulmonary arterial P02 (120–320 mm Hg) reduced the pressor response to alveolar hypoxia. This effect of arterial Po2 could be counteracted by a rise in ventilation frequency. Pulmonary arterial hypoxemia during periods with arrest of ventilation caused brisk vasoconstrictor responses. It was apparent that the combined effect of alveolar and arterial Po2 on PVR depends on the relative intensities of ventilation and perfusion, the alveolar Po, being the main denominator for the vasoconstriction effect. The results have been discussed in relation to the possible shape of the Po2 gradient from alveolar gas to lumen of small resistance vessels.
Release, Reuptake and Net Uptake of Dopamine, Noradrenaline and Adrenaline in Isolated Sheep Adrenal Medullary Granules
Authors: Lishajko F. 
Published: December 2008

AbstractIsolated storage granules from sheep adrenal medullary cells incubated in isotonic K‐phosphate at 37° C give off dopamine (DA) and adrenaline (A) at characteristically different rates following an exponential course. The average half time for the DA release in granules during the prevailing conditions was 22 min and for A 49 min. Noradrenaline (NA) was released more rapidly during the initial stage and thereafter exponentially at a slow rate. DA in concentrations of 3 × 10‐5 M in the incubation fluid increased the half time for DA to 34 min, owing to reuptake, and decreased it for A to 43 min.Addition of ATP‐Mg, 3 mM, considerably decreased the release rate of DA as well as that of NA and A, presumably owing to inhibition of release and increased reuptake. In the presence of ATP‐Mg the addition of 3 × 10‐5 M DA further retarded the net release of DA from the storage granules.After partial depletion, the granules take up DA in the presence of ATP‐Mg. This effect is inhibited by reserpine. No net uptake of NA or A was observed in partially depleted granules in the presence of added ATP‐Mg. Addition of ATP‐Mg retards the release of soluble proteins concomitantly with catecholamines. The rapidly released NA has been localized in the heavy granule fractions.
Metabolism of14C‐Histamine in Domestic Animals: Goat
Authors: Eliassen K. A. 
Published: December 2008

AbstractIt has been suggested that increasedin vivoformation of histamine might he of importance in the pathogenesis of some diseases in ruminants. However, little is known about the degradation of i.v. injected histamine in these species. In the present study isotope dilution technique and paper chromatography were used to examine urinary14C‐metabolites subsequent to i.v. injection of14C‐histamine to the goat. During the first week after administration, 80–90 per cent of the activity was found in urine, and about 1 per cent in feces. Known metabolites accounted for 91 –108 per cent of the urinary radioactivity. Oxidative deamination of histamine to imidazoleacetic acid and its riboside seemed to be the only pathway of quantitative importance for histamine degradation in the goat. Paper chromatography revealed that histaminol (4(5)‐imidazolyl‐ethane‐2‐ol) is a metabolite of histamine in the goat accounting for about 2%of the urinary radioactivity.14C‐histaminol is formed when liver or kidney homogenates are incubated with14C‐histamine.
pH‐Dependence of the Mechanism in the Duodenal Bulb Inhibiting Gastric Acid Responses to Exogenous Gastrin
Authors: Andersson Sven. , Nilsson Göran 
Published: December 2008

AbstractGastric secretion was stimulated by intravenous infusion of gastrin n Pavlov and Heidenhain pouch dogs provided with isolated pouches of the duodenal bulb. Lowering the intrabulbar pH to pH 1.1 –1.3 almost abolished the acid response to a low dose of gastrin, whereas the inhibition of secretory responses to higher doses was less pronounced. Inhibition of secretory responses to a fixed submaximal dose of gastrin did not occur until the bulbar pH was reduced to 2.0–2.5. Secretory responses to threshold doses of gastrin, on the other hand, were significantly inhibited already at pH 3–4. The results question the concept that very low intra‐duodenal pH is required to activate the mechanism by which acid in the duodenum inhibits gastric acid secretion.
Kininogen in Plasma from Cat, Hamster and Guinea‐pig
Authors: Gautvik Kaare 
Published: December 2008

AbstractThe kininase activity and the level of the two kininogens, substrate 1 and 2, have been determined in plasmas from cats, hamsters and guinea‐pigs. Kininase activity was found to be far more pronounced in the latter type of plasma than in the former ones. The efficiency of di‐sodium edetate and phenanthroline as kininase inhibitor was also evaluated in the three plasma types. In plasma from cat and hamster, human plasma kallikrein was found to release kinins from the socalled substrate 1 only, whereas in guinea‐pig plasma the same agent released kinin from both types of kininogens. The animal's own saliva acted only upon substrate 2 in plasma from cat and guinea‐pig, whereas it induced kinin formation from both substrates in plasma from hamster. Ellagic acid and glass contact released kinins from substrate 1 only in all three plasma types. Intravenous injection in hamsters and guinea‐pigs of a buffered solution of ellagic acid, caused pronounced effects on blood pressure and respiration. On repeated injections these effects subsided. After four such injections the concentration of substrate 1 in arterial blood samples from hamsters was found to be very low (varying from 0 to 20 %). The level of substrate 2 was, however, unchanged. The level of substrate 1 reached 83 % of the initial value after 24 hrs.
Relations of Polyuria and Polydipsia in Experimental Diabetes Insipidus
Authors: Olsson Kerstin 
Published: December 2008

AbstractHypothalamic radio‐frequency lesions were produced in unanesthetized goats with the use of thermo‐couple electrodes permanently implanted into the median eminence region. Lesions restricted to the median eminence induced the triphasic response typical of experimental diabetes insipidus (DI). The polyuria of the temporary phase of DI developed before the polydipsia commenced. The increased water intake was apparently secondary to the excessive renal water loss. When the median eminence lesions were extended into the midhypothalamic region no clear distinction could be made between the onset of polyuria and polydipsia. Similar lesions encroaching upon the anterior hypothalamus and affecting the paraventricular nuclei, caused temporary hyperdipsia but no transient polyuria, or a much delayed temporary increase in urine flow. All three types of lesions induced the permanent phase of DI after a latent period of 6 to 11 days. The polydipsia of the permanent phase occurred after the commencement of the polyuria (observations in 2 animals), and was evidently due to a physiological stimulation of the thirst mechanism.
Effect of Salicylate Treatment on Fetal and Maternal Prothrombin Time in the Mouse
Authors: Eriksson Margareta 
Published: December 2008

AbstractIn order to investigate earlier observed salicylate‐induced fetal hemorrhage, sodium salicylate or dicumarol was given i.m. to A/Jax mice on the 17th gestation day. Prothrombin time was measured in the fetuses and the mother at autopsy at different times after injection. A decrease in the prothromth concentration was found in fetuses with salicylate‐induced hemorrhage after 4, 8 and 12 hrs, but not after 24 hrs. Fetuses wihout hemorrhages and the mothers in the salicylate group had the same prothrombin time as those in the control groups. Dicumarol lowered the prothrombin concentration in both the mother and fetuses, but did not cause visible hemorrhage. The possible correlation between salicylate‐induced hemorrhage and hypo‐prothrombinemia is briefly discussed.