bluuebunny/crossref_metadata_2025 huggingface dataset:
The spatial distribution of odour induced potentials in the olfactory bulb of char and trout (Salmonidae)
Authors: Thommesen Georg
Published: December 2008

Monopolar 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

Isolated 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

An 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

A 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

The 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

Regenerative 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

The 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

The 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

The 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

The 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

Lactate 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

Repeated 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

The 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

The 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

Blood 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

Sympathetic 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

Inhibition 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

The 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.
Distribution of maximum coronary blood flow in the left ventricular wall of anesthetized dogs
Authors: Bagger Henning
Published: December 2008

Blood flow in the circumflex branch of the left coronary artery was recorded by electromagnetic flowmeter. In a group of dogs progressive hemodilution was performed until the diastolic reactive hyperemic response to 10 s occlusion of the circumflex branch disappeared (“optimum” hemodilution). At this degree of hemodilution the distribution of blood flow in the left ventricular free wall was evaluated by measuring tissue activity concentrations of Xe‐133 and radioactive microspheres after bolus injection into the aortic root. “Optimum” hernodilution was accompanied by a sixfold increase in systolic coronary flow, a 3‐fold increase in diastolic flow and a relative endocardial hypoperfusion. These results indicate that the endocardial blood flow reserve is lower than the epicardial. This conclusion is supported by the influence of spontaneous oscillations of arterial blood pressure (Traube‐Hering waves) on systolic and diastolic coronary blood flows before and during “optimum” hemodilution. In another group of dogs maximum coronary vasodilatation was produced by occlusion of the left coronary artery for 10 s. In this group the distribution of Xe‐133 and radioactive microspheres were measured after bolus injection into the aortic root at peak diastolic reactive hyperemia. The epi‐ and endocardial distribution of both Xe‐133 and microspheres was uniform in the left ventricular wall, indicating a uniform flow to these regions. This might be explained by an increased endocardial perfusion during systole due to loss of myocardial contractility or by a decline towards resting level in epicardial flow at the time of injection, corresponding to a shorter duration of the hyperemic period in the epi‐ than endocardial region.
Blood flow, calcium deposition and heat loss in reindeer antlers
Authors: Hove Knut , Steen Johan B.
Published: December 2008

Antler blood flow was studied in a 2 year old male reindeer during the last half of the antler growth period using an electromagnetic flow probe chronically implanted around the superficial temporal artery. Arterio‐venous (a‐v) differences of calcium were measured on antler blood. The blood flow increased from 60–90 ml/min when the antler was half‐grown to 100–120 ml/min when fully developed. Subsequently a reduction was observed towards shedding. Positive a‐v plasma calcium differences (on average 0.2 mM) were recorded during the period of active growth. Two bulls maintained positive a‐v calcium differences after a 48 hour starvation period, in spite of reduced arterial calcium concentrations. Exercise to near exhaustion caused a 2°C rise in the rectal temperature. Antler blood flow was decreased immediately after exercise and returned to pre‐exercise values usually within 5–10 min. Since no overshoot in antler blood flow was recorded during the hyperthermia it is concluded that variations in blood perfusion of the antlers are without importance in the defence against hyperthermia during and after exercise.
Activity of acid hydrolases in skeletal muscle of untrained, trained and detrained mice of different ages
Authors: Pilström Lars , Vihko Veikko , ÅStröm Eva , Arstila Antti U.
Published: December 2008

The activities of p‐nitrophenylphosphatase, β‐glucuronidase and β‐N‐acetylglucosaminidase from crude skeletal muscle homogenates of 4 and 7 months old mice were assayed after short‐term intensive and long‐term moderate training and after terminated training. In the older untrained mice the activity of the hydrolases was higher than in the younger mice. The level increased with training and this increase was far more pronounced in the older animals. Cessation of training for 7 and 21 days decreased this activity in the older animals but it was again increased 42 days later and cIose to the level observed in the trained mice. In young mice 3 days' terminated training increased the activity of the acid hydrolases above the level of the trained animals but after additional 4 and 11 days' terminated training the activity decreased to slightly below that of the trained mice. The changes were most prominent in the activity of β‐glucuronidase and to a lesser extent in that of β‐N‐acetylglucosaminidase while p‐nitrophenylphosphatase activity was almost unaffected by training or terminated training. The effects of terminated training can he intepreted as representing altered catabolic processes in the turn‐over of tissue components of skeletal muscle.
Anticholeretic effect of somatostatin in anesthetized dogs
Authors: Holm Inger , Thulin Lars , Samnegård Hans , Efendic Suad , Tydén Gunnar
Published: December 2008

Somatostatin, 0.2‐1.0 βg. kg‐l min‐1, was administered i.v. in 5 anesthetized dogs. Following 9‐min infusions, hepatic bile output was found to decrease by approximately 50% after a latency of 6 min. The mode of action suggests that somatostatin inhibits hormone‐induced bile output.
Insulin production by pancreatic islets of obese‐hyperglycemic mice cultured for one week in different glucose concentrations
Authors: Andersson Arne , Asplund Kjell , Larkins Richard
Published: December 2008

Anderson, A., K. Asplund and R. Larkins, Insulin production by pancreuric islets of obese‐hyperglycemic mice cultured for one week in different glucose concentrations. Acta physiol. scand. 1978. 104. 377–385.

Culture of pancreatic islets isolated from obese‐hyperglycemic mice (gene symbol oh) for one week in media containing widely different concentrations of glucose (3.3, 5.6 or 16.7 mM) was found to markedly influence the functional behaviour of the islet B‐cells. Thus, the insulin content of islets cultured at 3.3 or 16.7 mM glucose (subphysiological or supraphysiological glucoce concentrations respectively) was markedly reduced. Islets cultured in 5.6 or 16.7 mM glucose displayed a normal insulin secretory response when stimulated with glucose, whereas islets cultured in a subnormal glucose concentration (3.3 mM) showed a reduced insulin response to glucose stimulation in batch type incubations and also lacked a second phase of insulin secretion in islet perifusion experiments. The rate of insulin biosynthesis of non‐cultured ob/ob islets was higher than that of islets from Lheir lean siblings but cuiture for one week in 3.3 mM glucose induced a pronounced impairment of the insulin biosynthesis in islets of obese as well as lean mice. The present data indicate that the hyperfunction of the islets of the ob/ob mouse at least in part is a reversible phenomenon, suggesting that inherent properties of islet B‐cells do not act as “primary” factors in the development of the obese‐hyperglycemic syndrome.
Metabolic and cardiovascular responses to prolonged noradrenaline load and their antagonism by beta blockade in the rat
Authors: Harri By Mikko N. E.
Published: December 2008

Harri, M. N. E. Metabolic and cardiovascular responses to prolonged noradrenaline load and their antagonism by beta blockade in the rat. Acta physiol. scand. 1978. 104. 402–414.

Rats were given daily injections of noradrenaline (0.5 mg/kg), alprenolol (20 mg/kg), or both together for 17 to 39 days. Noradrenaline injections increased the size of the heart, interscapular brown adipose tissue (ISBAT) and, when the injections were given at a thermoneutral environment, the metabolic activity of the ISBAT. Alprenolol injections tended to reduce the size of the heart and ISBAT and, at a thermoneutral environment, metabolic activity of the skeletal muscle. Furthermore, noradrenaline treatment improved tolerance against body cooling in water at 25°C and enhanced calorigenic response to injected noradrenaline. The metabolic alterations in the rats injected with both drugs together resembled more those of the animals injected with alprenolol only than those of the noradrenaline treated rats. It can be thus concluded that alprenolol, when given together with noradrenaline, antagonized noradrenaline‐induced metabolic alterations in the organism. However, the increased pressor response to infused noradrenaline, which was evident in the alprenolol treated animals, was not seen in the animals treated with both drugs. By contrast, these animals, like also the noradrenaline‐treated animals, showed decreased pressor response to noradrenaline. This finding suggests that prolonged beta blockade does not abolish the decreased sensitivity of alpha‐adrenoreceptors following prolonged noradrenaline load. On the other hand, the hypotonic response to a beta adrenergic drug, isoprenaline, was reduced by prolonged beta blockade despite simultaneous noradrenaline injections.
Effect of synthetic substance P on internal carotid artery blood flow in man
Authors: Samnegård Hans , Thulin Lars , Tydén Gunnar , Johansson Claes , Muhrbeck Olle , Björklund Christer
Published: December 2008

Samnegård, H., L. Thulin, G. Tydén, C. Johansson, O. Muhrbeck and C. Björklund, Effect of synthetic substance P on itzternul carotid artery blood flow in man. Acta physiol. scand. 1978. 104. 491–495.

Internal carotid artery blood flow was studied by peroperative electromagnetic blood flow measurement in 7 patients following 9 intravenous infusions of synthetic Substance P, 2 ng·kg‐1.min‐1. The blood flow responses varied interindividually. No significant blood flow changes were observed for the whole group. The arterial mean blood pressure decreased significantly.
Effect of plasma H+‐ion concentration on pancreatic HCO‐3 secretion
Authors: RÆDER MORTEN , MO ARVE , AUNE SNORRE
Published: December 2008

The relationship between the rate of pancreatic HCO‐3 secretion and plasma H+‐ion concentration was investigated in 15 pentothal anesthetized, secretin infused pigs (1.8 C.U./kg b.w. h‐1 intravenously) during acute metabolic and respiratory acid‐base disturbances. Pancreatic HCO‐3 secretion increased to 196 ± 10% of control during alkalosis and fell to 41 ± 4% of control during acidosis. Partial metabolic compensation of respiratory acidosis restored HCO‐3 secretion to 87 ± 6% of control. A proportional relationship was found between HCO‐3 secretion and plasma pH. Different, proportional relationships were found between HCO‐3 secretion and plasma HCO‐3 concentration during metabolic and respiratory acid‐base changes. HCO‐3 secretion was independent of H+‐ion concentration in pancreatic juice. Plasma H+‐ion concentration, therefore, seems to determine the rate of pancreatic HCO‐3 secretion. This finding supports the hypothesis that a proton pump is responsible for pancreatic HCO‐3 secretion.
Effects of vasoactive intestinal polypeptide on blood flow, motility and fluid transport in the gastrointestinal tract of the cat
Authors: EKLUND STEFAN , JODAL MATS , LUNDGREN OVE , SJOQVIST ANDERS
Published: December 2008

The effect of close intraarterial infusions of vasoactive intestinal polypeptide (VIP) on gastric motility, intestinal fluid transport and colonic motility were studied in the cat. Regional blood flow was also followed in all experiments. In the stomach VIP produced a gastric relaxation and a blood flow increase. The motility response was similar to that observed when eliciting the vago‐vagal reflex relaxation by distending the esophagus. In the small intestine a hyperemia and a decrease of net water uptake was observed. When infusing small amounts of VIP a decrease of net water uptake was seen without any change of intestinal blood flow. Large amounts of VIP produced a transient secretory state in the small intestine. In the colon a hyperemia was seen immediately upon starting the infusion of the drug. After 2–3 min of infusion a contraction of the colon was apparent. The administration of atropine to the animal did not significantly affect any of the responses produced by VIP. The results are discussed in relation to VIP as a possible neurotransmitter in the gastrointestinal tract.
Prevention of protein extravasation in the brain by an anion transport inhibitor in acute experimental hypertension in rats
Authors: HANSSON HANS‐ARNE , JOHANSSON BARBRO B.
Published: December 2008

Acute experimental hypertension induces protein leakage in the brain. The protein is thought to be, at least to a great extent, transported through the endothelial cells by pinocytosis. An anion transport inhibitor, 4 acetamido‐4‐isothiocyano‐stilbene‐2,2′‐disulfonic acid, markedly reduced adrenaline or bicuculline‐induced leakage of 125IHSA and Evans blue‐albumin in all areas of the rat brain. The preventive effect of dexamethasone was less pronounced and no effect was seen of haloperidol.
Possible role of thiamine in neuromuscular transmission
Authors: WALDENLIND LENNART
Published: December 2008

Pyrithiamine (50 mg/kg), a thiamine antagonist, decreased the muscle twitches of the rat masseter muscle at stimulation frequencies above 1 Hz 40–80 min after an i.v. injection. The post‐tetanic potentiation (PTP) induced by nerve stimulation of the masseter muscle was abolished by pyrithiamine. Administration of thiamine restored the muscle twitches at stimulation frequencies above 1 Hz and the PTP. The muscle twitches elicited by direct muscle stimulation were not affected by pyrithiamine treatment. The abolishment of the PTP was accompanied by a decrease in thiamine and thiamine‐diphosphate. The pyruvate level in the blood was unchanged after pyrithiamine treatment. Oxythiamine, on the other hand, had no effect on the PTP but increased the pyruvate level in the blood. Fern extract which contains thiaminase I also abolished the PTP–an effect reversible by the addition of thiamine. The frequency‐induced depression of the muscle twitches induced by pyrithiamine was similar to the effect of low doses of d‐tubocurarine (8 μg/kg). The results support the hypothesis that thiamine may play a role in neuromuscular transmission.
Ventilatory and occlusion pressure response to CO2 and hypoxia with resistive loads
Authors: BARNETT THOMAS B. , RASMUSSEN BIRGER
Published: December 2008

Steady‐state responses to hyperoxic hypercapnia and eucapnic hypoxia were measured both as minute ventilation (VE) and as inspiratory mouth occlusion pressure (P0.1) with and without 25 cm H2O/l/s added resistance (R). Reduction in slope of the ventilatory response to CO2 with R was highly significant in all 3 subjects whereas the response to hypoxia was barely significantly reduced in 1 subject and not significantly decreased in two. Although P0.1 was higher with than without R under all conditions, the slope of the P0.1 response to CO2 with R was not increased in two subjects and only slightly increased in the third. The slope of the P0.1 response to hypoxia was significantly greater in all subjects with R. Expiratory reserve volume was increased with R but the change was the same with hypoxia and hypercapnia. We conclude that ventilation is better maintained with resistive loading during hypoxia than during hypercapnia and that this results from a greater force output of inspiratory muscles as reflected by a higher P0.1. This suggests a greater neural output to these muscles.
Differences in renal and submaxillary renin release after stimulation with isoprenaline and noradrenaline
Authors: BING JENS , POULSEN KNUD
Published: December 2008

It is confirmed that while noradrenaline stimulates release of submaxillary as well as renal renin, isoprenaline only stimulates renal renin release. The effects of these two adrenergic agonists differ in several other ways. The kidneys respond to isoprenaline with a dose dependant renin release. As a contrast the submaxillary glands respond to noradrenaline by no or by non‐dose‐dependant release. After single doses of the agonists the isoprenaline induced renin release is of short duration, contrasting with a prolonged renin release after injection of noradrenaline. The kidneys are able to respond to repeated doses of both agonists, while the submaxillary glands most often only respond to the first dose. While the effect of noradrenaline is blocked by pretreatment with phenoxybenzamine, this blocker is without effect when given after noradrenaline. The two agonists do not provoke any increase in plasma renin in mice which have been both sialoadenectomized and nephrectomized.
Capillary permeability measured by bolus injection, residue and venous detection
Authors: SEJRSEN PER
Published: December 2008

Kinetic analysis of residue and outflow curves of y‐emitting indicators such as chromium‐51‐EDTA and iodide‐131‐thalamate from skeletal muscle gives the possibility to determine the extraction fraction and the plasma flow, and from these two values the capillary diffusion capacity can be calculated (Sejrsen 1970, preliminary report). This is possible both for the transport from blood to tissue and from tissue to blood. This alternative method has been compared in the autoperfused cat gastrocnemius preparation with the indicator diffusion method based on venous registration of a diffusible test indicator and an intravascular reference indicator (Chinard et at. 1955, Crone 1963). The results of the five independent measurements show good agreement. Calculation of the permeability Pd based on a capillary surface area of 7 000 cm2/100 g of tissue gives values of 1.05–10‐5, 1.10–10‐5, and 1.16–10‐5 cm/s, which is in agreement with results obtained by other investigators. The permeability was equal in both directions, and thus the capillary membrane seems to function as a symmetrical membrane. Using an area of 5 000 cm2/100 g which presumably is more realistic at the plasma flow range used gives Pd values around 1.5–10‐6 cm/s. The effective pore area is calculated to constitute 1/50 000 of the capillary surface area. Calculation of volumes of distribution in the muscle tissue gave intravascular plasma volumes of 1.8 to 2.0 ml/100 g, an extravascular volume of 12.4 and 15.2 ml/100 g and a final monoexponential component constituting a compartment of 5.4 and 7.0 ml/100 g from residue and venous curves, respectively. The last mentioned compartment constitutes nearly 50 per cent of the extravascular space, and it is suggested, that it is located inside the sarcoplasmic reticulum, which anatomically constitutes about 50 per cent of the interstitial space. The total area of contact between the longitudinal and the transversal tubules in this subsystem, which is the membrane of the lateral saccus, is estimated to about 6 times the capillary surface area at a plasma flow of 15 ml/100 g min which gives a permeability about 60 times lower for this membrane compared to the capillary membrane.
A phenomenologic evaluation of CO2‐diffusion restriction in kidney tubules studied in an artificial membrane system
Authors: Sohtell Morgan
Published: December 2008

The chemical course in a multi‐membrane system with interacting H+ and HCO3 ions has been described phenomenologically as an analogy of the neutralisation reaction between secreted H+ and filtered HCO3 ions in the proximal tubules of the kidney. It was shown that the produced CO2 gave the highest PCO2 in the asymmetrically placed reaction centre, which favours a build‐up of a high intratubular PCO2. The CO2 transport was dependent on the rate‐limiting permeation of the reacting ions, and the permeation could be increased by the influence of solutions of macro molecules such as carbonic anhydrase, albumin and dextran.
Synaptosomal accumulation of intracerebral injected amino acids
Authors: Karppinen Anneli , Kumpulainen Elsa , Lähdesmäki P.
Published: December 2008

The distribution of the labels of [35S]taurine, [3H]lysine, [14C]glutamate and [11C]norleucine in mouse brain subcellular fractions was followed after intracerebral injection in vivo. [35S]taurine, [3H]lysine and [14C]gluta‐mate and its metabolites accumulated in the nerve terminals, lysine and glutamate also occurring in the synaptic vesicles, while taurine remained mainly in the soluble synaptoplasm. [14C]norleucine penetrated the brain cell membranes slowly, but was still bound to the synaptic vesicles to a greater extent than taurine.
Rapid increase of glycosaminoglycans in the aorta of hypercholesterolemia rats; a negative correlation with plasma HDL concentration
Authors: Tammi Markku , Rönnemaa Tapani , Vjikari Jorma
Published: December 2008

Rats were kept either on a standard laboratory diet or a high cholesterol, olive oil diet for periods ranging from 1 day to 22 weeks. The effect of the high cholesterol, olive oil diet on the concentrations of cholesterol, glycosaminoglycans (GAGs) and collagen in aortic intima‐media, were studied and the developing hyper‐lipidemia was characterized. The concentration of cholesterol in rat aorta was increased after 22 weeks' high cholesterol, olive oil diet, while collagen concentration was not affected. On the contrary, the concentration of aortic sulphated GAGs was significantly increased already after one week's high cholesterol, olive oil diet. The diet increased the formation of a cholesterol‐rich very low density lipoprotein (VLDL), decreased high density lipoprotein (HDL)‐associated cholesterol and phospholipids, but had virtually no effect on low density lipoprotein (LDL)‐lipids. The concentrations of VLDL‐cholesterol and ‐phospholipids showed positive correlations with the concentration of aortic GAGs (r = 0.89 and 0.83, respectively, P < 0.05 for both). Stronger (negative) correlations were found between aortic GAGs and HDL‐cholesterol and ‐phospholipids (r = ‐0.94 for both, P <0.01) suggesting that HDL may have a role in the control of arterial sulphated GAG concentration.
In vitro effects of growth hormone on protein synthesis and amino acid transport in the rat diaphragm after acute hypophysectomy
Authors: Albertsson‐Wikland Kerstin , Edén Staffan , Isaksson Olle
Published: December 2008

The effects of growth hormone (G H) in vitro on phenylalanine‐14C incorporation to assess protein synthesis and on a‐aminoisobutyric‐l‐3H accumulation to measure amino acid transport in the diaphragm muscle of the rat were investigated 2, 6 and 24 h after hypophysectomy or sham‐operation. In hypophysectomized animals protein synthesis was depressed. GH in vitro was without effect 2 h after hypophysectomy but stimulated protein synthesis 6 and 24 h after the operation. Six hours after hypophysectomy amino acid transport was enhanced and further stimulated by GH. After 24 h amino acid transport was depressed but was stimulated to normal levels by GH. Six hours after sham‐operation protein synthesis was depressed, but was stimulated by GH. After 24 h protein synthesis was normalized and GH was without effect. GH did not influence amino acid transport after sham‐operation. Plasma levels of GH were undetectable after hypophysectomy, markedly depressed 2 and 6 h after sham‐operation, but normal after 24 h. It is concluded that tissue responsiveness to GH develops a few hours after hypophysectomy.
Potassium permeability of the mesothelium of the frog mesentery
Authors: Frøkjær‐Jensen J. , Christensen Ove
Published: December 2008

The mesothelium of the mesentery is a single cell layer described to offer no or every little hindrance to diffusion of small water soluble solutes. We have measured the potassium permeability of the mesothelium of the frog mesentery both in vivo and in vitro. The permeability measured in vivo–using K+–sensitive microelectrodes is 2.4 times 10‐5 cm s‐1. In vitro measurements using conventional tracer flux technique on isolated mesentery yields a K+‐permeability of 5.7 times 10‐5 cm s_1. These values are 15–30 times smaller than values previously reported from in vitro experiments on rat and rabbit mesentery. Also, the permeability is 12–15 times lower than the K+‐permeability of the capillary wall determined on single capillaries in the frog mesentery. In the frog mesentery the mesothelium thus represents an important diffusion barrier compared to the capillary wall. This may be critical in experiments where filtration and reflexion coefficients of the capillaries are determined from measurements of fluid exchange across the capillary wall in response to application of hypertonic solutions on the surface of the mesentery.
The Spitzbergen reindeer‐a winter‐dormant ungulate?
Authors: RINGBERG TATA
Published: December 2008

Seasonal changes in serum levels of growth hormone, Cortisol and thyroxine in calves and adult Spitzbergen reindeer (Rangifer taranilus platyrynehus) were measured and compared to those previously found in Norwegian reindeer (R.t. tarandus). Cortisol did not differ significantly between summer and winter, or between the subspecies. Growth hormone and thyroxine exhibited highly significant seasonal changes and subspecific differences: winter levels of growth hormone were much higher than summer levels in the Spitzbergen reindeer, while Norwegian reindeer differed very little from season to season. Both Spitzbergen and Norwegian reindeer had markedly reduced thyroxine levels during winter, but the values from the former were much lower than those from the latter. In summer, however, the levels were equal. The high levels of growth hormone and low levels of thyroxine in the Spitzbergen reindeer during winter are indicative of high lipolytic activity and a reduced metabolic rate, respectively.