bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aspects on diamine oxidase activity and its determination
Authors: Andersson Anne‐Charlotte , Henningsson Stig , Persson Lo , Rosengren Elsa 
Published: December 2008

AbstractHomogenate of guinea‐pig liver and human placenta, tissues known to be rich in diamine oxidase, were incubated with 14C‐putrescine and the metabolites formed were determined. In the incubate of guinea‐pig liver, the major metabolites were GABA and some unidentified compound(s); Δ1‐pyrroline and 14CO2 were also obtained. In both the maternal and fetal parts of human placenta, radioactive GABA and the unidentified compound(s) as well as Δ1‐pyrroline were found. The results indicate that GABA is an important intermediate in putrescine metabolism. Determination of the amount of Δ1‐pyrroline is thus not well suited as a measure of the diamine oxidase activity in tissues.
Tension‐length behaviour of a molluscan smooth muscle related to filament organisation
Authors: Cornelius F. , Lowy J. 
Published: December 2008

AbstractUnder optimal activation conditions we obtain an active tension‐length curve with a well‐defined plateau region. The plateau can be explained in terms of a sliding filament mechanism in which double overlap of the thin filaments does not interfere with cross‐bridge formation between thick and thin filaments of the appropriate polarity.
The spatial distribution of odour induced potentials in the olfactory bulb of char and trout (Salmonidae)
Authors: Thommesen Georg 
Published: December 2008

AbstractMonopolar DC‐recordings were made of the gross responses from the olfactory bulb of char (Salvelinus alpinus syn. Salmo alpinus L.) and trout (Salmo trutta L.) during stimulation with different odours. The response features studied were: the magnitude and polarity of the slow potential shift, the amplitude of the induced waves and their asymmetrical waveform. Amino acids elicited the largest responses in the lateral part of the bulb. Water containing “crude fish odour” caused the largest responses in the rostral and medial parts. The results demonstrate odour specific differences in the localization of the bulb responses and the separate origin of the slow potential and the induced waves.
Neuroeffector maturity of portal veins from newborn rats, rabbits, cats and guinea pigs
Authors: McMurphy Dorothy Stage , Ljung Bengt 
Published: December 2008

AbstractIsolated portal veins from newborn and adult rats, rabbits, cats and guinea pigs were studied isometrically. Spontaneous activity and induced responses to transmural nerve stimulation (NS), noradrenaline, tyramine, acetylcholine and BaCl2 were quantitated. In agreement with our previous observations the portal vein of the newborn rat was found to lack spontaneous activity and responsiveness to applied stimuli whereas the newborn rabbit's portal vein showed inconsistent and weak responses. In the neonatal cat and guinea pig portal veins the pattern of the spontaneous activity and induced responses resembled those found in vessels from adult animals. It is concluded that the portal vein maturity at birth in several respects corresponds to the level of somatic development of the animal. Furthermore, the previously described dramatic neuroeffector development of the portal vein during the postnatal period in the rat corresponds to prenatal events in cats and guinea pigs which are more highly developed at birth. Consequently, the lack of responsiveness of the portal vein during the first week of life does not seem to be secondary to the hormonal and hemodynamic adjustments during the neonatal period. Rather, the postnatal development of the rat portal vein occurs according to a genetically predetermined schedule, possibly in parallel with the ontogenesis of vascular control in general.
An electronic differential pressure flowmeter and a resistance meter for continuous measurement of vascular resistance
Authors: Per‐Olof Grände  , Borgström Per 
Published: December 2008

AbstractAn electronic differential pressure flowmeter for mean blood flow measuring and its use in a resistance meter for continuous recording of vascular resistance is described. The flowmeter allows accurate and linear registration also in the small flow range (< 10 ml/min), thus appropriate for use in small experimental animals.
Effects of the antidiuretic hormone, arginine vasotocin, theophylline, filipin and A23187 on cyclic AMP in isolated frog skin epithelium (Rana temporaria)
Authors: Anders H. Johnsen  , Nielsen Robert 
Published: December 2008

AbstractA method for measuring cAMP in frog skin epithelium was developed. The epithelia were isolated after collagenase‐treatment. cAMP was extracted by boiling water and the extract was purified on dry AI2O3. The change with time of the cAMP level after addition of arginine vasotocin (AVT) was studied. The hormone caused a rapid increase in cAMP level with a maximum after 3–5 min, whereafter the cAMP level declined. Incubation with AVT made the epithelia refractory to a second dose of AVT, which indicates that the decline in cAMP level was caused by a feedback mechanism and not by inactivation of the hormone. cAMP appeared evenly distributed in all cell‐layers of the epithelia both before and after stimulation with AVT. Theophylline caused a rapid increase in the cAMP level, which remained elevated for at least 45 min. Addition of the ionophore A23187 or of filipin had no effect on the cAMP level. However, in the presence of theophylline, A23187 enhanced the cAMP level, whereas filipin had no effect. Therefore the involvement of cAMP in the action of A23187 has to be considered.
The extracellular potassium concentration in brain cortex following ischemia in hypo‐ and hyperglycemic rats
Authors: Hansen Anker Jon 
Published: December 2008

AbstractThe extracellular potassium concentration, [K+]e, was measured in the brain cortex of hypo‐, normo‐ and hyperglycemic rats following brain ischemia. The increase in [K+]θ in control rats could be characterized by 3 phases: an initial slow rate of rise where the [K+]θ rose in 2 min from 3 to 9 mM followed by an abrupt, steep increase to 60 mM within 10 s and finally a slow rise to 80 mM. In the hyper‐ and hypo‐ glycemic rats the same pattern appeared, but there were significant differences in the time course. The duration of the initial phase was approximately doubled in the hyperglycemic and halved in the hypoglycemic group. The [K.+]θ at which the steep increase was elicited was 8–10 mM in all groups. It is concluded that the duration of the initial phase is dependent upon available stores of glucose in the brain.
Electrical activity of rat anterior pituitary cells in vitro
Authors: Ozawa Seiji , Sand Olav 
Published: December 2008

AbstractRegenerative responses were seen in most cells either after cessation of an inward current pulse or during an outward current pulse. Two cell groups were distinguished electrophysiologically. Type I cells showed action potentials with maximum rate of rise of 21.2 ± 9.0 V/sec (mean ± S.D., n= 19), while type II cells generated small graded depolarising responses with maximum rate of rise less than 3 V/s. The resting potentials of type I and II cells were 31.8± 14.9 mV (n = 19) and 41.7 ± 9.8 mV (n = 31), respectively. The steady‐state current/voltage relationship was linear for both cell types when the membrane potential was more negative than — 60 mV. An outward rectification appeared when the membrane potential was more positive than —40 mV. The input resistance was smaller in type I cells (274±212 MΩ, n=19) than in type II cells (1 112 ± 456 MΩ, n=16). Even in Na‐free solution regenerative responses were observed in most cells. When the Ca2+ concentration was increased tenfold to 24 mM, the maximum rate of rise of the off‐response increased from 1.9 ± 0.8 V/s (n = 11) to 5.7 ± 2.12 V/s (n = 5). All‐or‐none action potentials could be evoked in this Ca2+ rich solution. Action potentials of similar maximum rate of rise could be evoked after replacing 24 mM Ca2+ with isomolar Sr2+. Prolonged action potentials were seen after substitution of Ca2+ for Ba2+. It is concluded that action potentials in most anterior pituitary cells have a Ca component, which in type I cells is additional to a Na component.
Blood flow distribution in the renal portal system of the intact hen. A study of a venous system using microspheres
Authors: Odlind Bo 
Published: December 2008

AbstractThe blood flow in the renal portal system of intact hens was characterized by determining the fractional distribution of 15 μm and 50 μm microspheres in this system after injection into a leg vein. Validation tests showed that only 50 μm spheres gave a reliable estimation of this distribution. The blood flow in the coccy‐geomesenteric vein was directed towards the liver in nearly all cases. On the average 44, 47 and 8% of the portal blood from the external iliac vein perfused the ipsilateral kidney, the liver and the lungs, respectively. However, the distribution of portal blood to these organs varied considerably between individuals and changed appreciably within 35 min in half the animals studied. The reason for these variations is not clear. The portal blood from the right and left external iliac veins was asymmetrically distributed in most animals illustrating the importance of local factors in its regulation. Variation was great in the regional distribution of portal blood within the kidney possibly due to local vasoconstriction of portal vessels. Further information e.g. on the regulation of renal portal blood flow is needed to explain its physiological significance. Microspheres provide a convenient method for such studies. A combination of microsphere and Sperber techniques allows us to determine the renal excretion efficiency of a given substance.
Estrogen and the relaxant effect of intramural noradrenaline on calcium induced contractures in depolarized rat uterus
Authors: Bengtsson Bengt 
Published: December 2008

AbstractThe influence of intramural noradrenaline on calcium induced contractures was studied in isolated preparations of rat uterus. The depolarized (127 mM KCl) myometrium of oophorectomized rats responded with contraction followed by a transient relaxation when exposed to 3 mM calcium. The threshold concentration of calcium, where the transient relaxation began to appear, was between 0.25 and 0.5 mM. Blockade of the β‐adrenoceptors with propranolol or noradrenaline depletion with reserpine completely removed the transient relaxation, indicating that the latter was due to release of intramural noradrenaline. Estrogen treatment abolished the relaxant effect of intramural noradrenaline, whereas progesterone was ineffective in this respect. Preparations from rats in natural estrus responded like estrogenized tissues, and diestrus preparations behaved as uteri of oophorectomized rats without estrogen treatment.
Vasodilatation and modulation of vasoconstriction in canine subcutaneous adipose tissue caused by activation of β‐adrenoceptors
Authors: Belfrage Erik 
Published: December 2008

AbstractThe present experiments were undertaken to study the balance between vascular α‐ and β‐adrenoceptors in canine subcutaneous adipose tissue during sympathetic nerve stimulation and noradrenaline injections. Propranolol potentiated and prolonged the vasoconstrictor response to close i.a. injections of noradrenaline. The vasoconstriction induced by brief nerve stimulation (0.5 to 8 Hz) was, however, unaltered by the β‐adrenoceptor blockade. During prolonged nerve stimulation the vasoconstrictor response was well maintained at 1.5 Hz but at 4 Hz there was a gradual escape. The escape phenomenon at 4 Hz was diminished by propranolol. The β1‐selective antagonist practolol, like propranolol, potentiated and prolonged the vasoconstriction induced by noradrenaline injections and reduced the vasoconstrictor escape during prolonged nerve stimulation at 4 Hz. Furthermore, the vasodilatation induced by noradrenaline injection or nerve stimulation during α‐adrenoceptor blockade was diminished by practolol. Practolol also blocked the lipolytic response to noradrenaiine and nerve stimulation. The β2‐selective antagonist H35/25 blocked the effects of the β2‐selective agonist salbutamol but failed to alter noradrenaline as well as nerve stimulation induced vascular and lipolytic β‐adrenoceptor responses. The present results provide further support for the hypothesis that vascular β‐adrenoceptors in adipose tissue are humoral (noninnervated), preferentially activated by circulating noradrenaline. Moreover, both vascular and lipolytic β‐adrenoceptors activated by noradrenaline in adipose tissue are best classified as β1‐adrenoceptors.
The effects of Triton‐detergents on the stretch receptor of the crayfish
Authors: Ottoson D. , Rydqvist B. 
Published: December 2008

AbstractThe effects of the non‐ionic detergents Triton X‐45 and Triton X‐100 on the action potential and the receptor potential of the stretch receptor neuron of the crayfish Astacus fluviatilis was studied with intracellular recording technique. Membrane currents were measured with voltage clamp technique. Both detergents blocked the action potential in 20–30 min at concentrations of 60–80 μM. Following blocking of spike electrogenesis the receptor potential evoked by stretch was obtained in isolation. With prolonged exposure of the neuron to the detergents there was a slowly developing reduction of the receptor potential and after 60–90 min no response to stretch could be obtained. These effects were produced without any significant change of the resting membrane potential. Following return to normal saline the responsiveness to stretch was completely restored in 80–100 min. Measurements with voltage clamp technique showed that the passive membrane properties were little affected by the two detergents. The stretch induced current on the other hand was severely depressed and almost abolished with prolonged exposure. The experimental results suggest that non‐ionic detergents block the spike electrogenesis and the transducer action by a selective action on the sodium channels of the membrane of the receptor neuron.
Relationship between lactate accumulation, LDH activity, LDH isozyme and fibre type distribution in human skeletal muscle
Authors: Tesch Per , Sjodin Bertil , Karlsson Jan 
Published: December 2008

AbstractLactate concentration, total LDH activity and muscle‐specific LDH isozymes were determined in pools of the two main types of human skeletal muscle fibres. Analyses were made from biopsy specimens obtained after intense dynamic exercise lasting approximately 30 s. Lactate concentration, total LDH activity and muscle‐specific LDH activity displayed higher average values for FT (fast twitch) fibres than for ST (slow twitch) fibres. In addition, positive correlations were found both between the individual percentage of FT fibres and muscle lactate concentration and between lactate concentration and total LDH activity and muscle‐specific LDH activity respectively.
Alprenolol fails to antagonize the metabolic changes following repeated thyroxine injections in the rat
Authors: Harri Mikko N. E. 
Published: December 2008

AbstractRepeated injections of rat with 1‐thyroxine (50 μg/kg daily for 5 five‐day weeks) retarded the weight gain of the animals and increased the absolute and relative size of the heart, adrenals and interscapular brown adipose tissue. In the myocardium and thigh muscle, thyroxine treatment resulted in elevated activity of oxidative enzymes, succinate dehydrogenase, malate dehydrogenase and citrate synthase, while the activities of glycolytic enzymes remained unchanged. Glycogen content of the heart was decreased following thyroxine regime. In the brown fat, on the other hand, thyroxine injections resulted in a reduction of the activity of oxidative enzymes. This reduction can be accounted for by the decreased protein (enzyme) content of the tissue due to deposition of fat. Furthermore, thyroxine treatment delayed the body cooling of the rats swimming in water at 25oC and enhanced hyperthermic response to injected noradrenaline. All these changes, which were not observable in rats treated with daily alprenolol (20 mg/kg) injections, were as pronounced in rats injected with alprenolol together with thyroxine as in rats injected with thyroxine only. It is concluded that beta blockers do not antagonize the metabolic changes due to hyperthyroidism.
On the chemical nature of the blood borne cardiotoxic material released from the feline small bowel in regional shock
Authors: Lundgren Ove , Haglund Ulf 
Published: December 2008

AbstractThe cardiotoxic material released into blood from the feline small intestine during a 2 or 3 h regional shock period (inflow pressure to the small intestine 30–35 mmHg during a continuous activation of the regional sympathetic vasoconstrictor fibres at 6 Hz) has been analyzed with regard to three properties: 1. molecular mass determined by molecular filtrations; 2. solubility in a nonpolar solvent (ether); 3. heat stability by heating plasma to 80oC for 30 min. The results obtained suggest that the cardiotoxic material consists of at least two heat stable fractions. One is water soluble with a molecular mass between 500 and 1 000 d and the other is lipid soluble with an unknown molecular mass.
“Fast” and “slow” skeleto‐fusimotor innervation in cat tenuissimus spindles; a study with the glycogen‐depletion method
Authors: Jami L. , Lan‐Couton D. , Malmgren K. , Petit J. 
Published: December 2008

AbstractThe glycogen‐depletion method was used to investigate the motor supply to tenuissimus with respect to the presence of fast β axons and to assess the total proportion of both fast and slow β‐innervated spindles in this muscle. In a first series of 5 expts., groups of motor axons with conduction velocities higher than 85 m/s were repetitively stimulated so as to produce glycogen depletion in the muscle fibres they innervated. The whole muscle was then quick‐frozen, serially cut, stained to demonstrate glycogen and examined for intrafusal glycogen depletion. Zones of glycogen depletion were found in 16 of the 46 examined spindles; they were most frequently located in the longest of the chain intrafusal muscle fibres. Since it is known that there are no purely fusimotor axons to tenuissimus with conduction velocities above 50 m/s, it was concluded that β axons are present among the fastest axons to this muscle. In a second series of 5 expts. as many motor axons as possible with conduction velocities above 60 m/s were stimulated. Zones of glycogen depletion were found in 19 of the 47 examined spindles. They affected chain fibres in about half of the instances and bag2 fibres in the others. As this latter location is characteristic of slow dynamic β axons, it was concluded that both slow and fast β axons occur regularly in the motor supply to tenuissimus. β‐innervation is present in at least 40% of tenuissimus spindles with almost no convergence of fast and slow β axons onto the same spindle.
Blood velocity in human arteries measured by a bidirectional ultrasonic doppler flowmeter
Authors: Risøe Cecilie , Wille SvenØSivind 
Published: December 2008

AbstractBlood velocities in 12 arteries were recorded by an ultrasonic doppler flowmeter in 11 young adults. Two major types of velocity patterns existed at rest. In certain arteries (the common carotid, the external carotid, the superficial temporal and the proper palmar digital arteries) flow was towards the periphery throughout the entire pulse cycle. Other arteries (the common femoral, the popliteal, the posterior tibial and the pedal artery) exhibited retrograde flow in part of the pulse cycle. In each individual a spontaneous variation between these two velocity patterns was observed in the subclavian, the axillary, the brachial and the radial artery. The velocity pattern of each artery is described, and absolute blood velocities at recognizable instances during the pulse cycle are given. The influence of peripheral resistance on the velocity pattern was investigated by reactive hyperaemia of the femoral artery. We find that not only is there an upward displacement of the resting femoral curve relative to the line of zero, but the shape of the velocity pattern is also changed. Our conclusion is that peripheral resistance is of major importance not only for the mean velocity, but also for the shape of the velocity pattern in the artery.
Attraction of nerve fiber outgrowth from sympathetic ganglia to heart auricles in tissue culture
Authors: Eränkä Olavi , Lahtinen Tuija 
Published: December 2008

AbstractSympathetic chain ganglia of 3‐day‐old rats were cultured in Rose chambers for 5 days. Each chamber contained either two ganglia or a ganglion and a piece of heart atrium. Visual examination failed to show an increased density or length of nerve fibers growing towards the other explant. However, actual measurements showed that the length of nerve fiber outgrowth towards the atrium explant was about 10% longer than the mean outgrowth to all directions, the difference being statistically significant (P< 0.0001). In ganglion‐ganglion pair cultures the nerve fiber outgrowth towards the other ganglion tended to be shorter than that to other directions. It is tentatively concluded that atrium explants exert a growth‐promoting influence on sympathetic nerve fibers in cultures, possibly due to diffusion of a growth‐promoting substance from the atrium explant.
Transient water diuresis and syndrome of inappropriate antidiuretic hormone secretion (SIADH) induced by forebrain lesions of different location
Authors: Rundgren Mats , Fyhrquist Frej 
Published: December 2008

AbstractInhibition of ADH‐secretion and transient water diuresis was observed as acute effects of radio‐frequency lesions in the septal region of goats. The water diuresis was not compensated for by drinking and therefore rapidly induced pronounced hypernatremia and hypovolemia. The development of hypovolemia was accompanied by a rise in plasma renin activity. Lesions of the same kind, but extending into the preoptic region near the medial portion of the supraoptic nuclei induced the inability to excrete excessive water characteristic of SIADH. Determinations of plasma arginine vasopressin suggested that the lesions causing SIADH did not produce any noticeable increase in basic ADH‐secretion. The results suggest that impulses from juxtaventricular receptors regulating ADH‐release and water intake to a considerable extent are transmitted via the septal region, and that elimination of this impulse traffic is sufficient to turn water balance to the negative side. However, reflex volumetric inhibition of the ADH‐secretion does not seem to be mediated by pathways passing through the septal region.
The distensibility of the resistance vessels of skeletal muscle in hypertensive patients
Authors: Hartling Ole , Svendsen Tage Lysbo , Nielsen Poul Ebbe , Trap‐Jensen Jens 
Published: December 2008

AbstractThe distensibility of the resistance vessels of skeletal muscle was evaluated in 23 patients with essential arterial hypertension (WSHO grade T‐II), and in 14 normotensive control subjects. Five of the hypertensive patients were well treated for over 2 years and 18 were untreated. The 133Xenon wash‐out rate from the anterior tibial muscle during reactive hyperemia was recorded before and during an increase of the vascular transmural pressure, brought about by application of a subatmospheric pressure to the leg. At ambient pressure the 133Xenon wash‐out rate did not differ between the normotensive and hypertensive subjects, reflecting equal muscle blood flows. However, when the transmural pressure was augmented the 133Xenon wash‐out rate in the normotensive subjects increased about twice as much as in the hypertensive patients. This suggests a decreased distensibility of the resistance vessels in hypertensive patients as compared to normotensive subjects, and supports the concept that structural changes of these vessels take place in arterial hypertension. Since the vascular distensibility was equally reduced in the untreated and well treated hypertensive patients it is indicated that the structural changes in the resistance vessels of the leg muscles do not readily decline during antihypertensive treatment.