bluuebunny/crossref_metadata_2025 huggingface dataset:
Diffusion of Sodium in Axoplasm of Myelinated Nerve Fibre. Potential Clamp Analysis
Authors: ÅRhem Peter
Published: December 2008

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

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

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

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

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

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

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

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

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

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

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

The fatiguability of the quadriceps muscle was investigated in 10 male subjects (25–40 yrs), with inter‐individual differences in fibre composition of their vastus lateralis muscles (range 25–65 % fast twitch, FT, muscle fibres). Fatiguability was assessed as the decline in maximal force (in % of initial values) with 50 repeated isokinetic knee‐extensions at fast angular velocity (3.14 radis). Each contraction lasted 0.5 s and the rest periods were about 0.7 s. Every subject was tested on two occasions and the standard deviation for a single determination of fatiguability was 1.47:., The decline in force after 50 contractions was on the average about 45%. The individual values varied, however, and a linear correlation was present between fatiguability and % FT fibres (r = 0.86, p–.0.01). It was concluded that development of fatigue in human skeletal muscle performing repeated fast dynamic contractions with maximal effort was most marked in muscles with a high proportion FT fibres. This finding was in conformity with earlier results from animal skeletal muscle preparations.
Adrenal Function in the Diabetic Mutant Mouse (Gene Symbol dbm)
Authors: Naeser Peter
Published: December 2008

Naeser, P. Adrenal function in the diabetic mutant mouse (gene symboI dbm). Acta physioi. scand. 1976. 98. 395–399.

The adrenal function in diabetes mutant mice with misty coat colour (dbm) was investigated by measurements of serum corticosteroids, adrenal weights and adrenal corticosteroid content. Furthermore, the adrenal corticosteroid content was studied in obese‐hyperglycemic mice (ob). In the dbm‐mice the serum corticosteroid levels were elevated at the age of 5 and 12 months although the adrenal weight only was significantly elevated at the age of 5 months. The adrenal corticosteroid content was significantly lower in the 12 months old dbm‐mice. In the ob‐mice the adrenal corticosteroid content was elevated at the age of 5 weeks, 5 and 12 months. It is concluded that in both the dbm‐mouse and the ob‐mouse there is an increased functional activity of the adrenal cortex which may reflect a pituitary hypersection of ACTH, perhaps as a manifestation of a common hypothalamic disorder.
Slow Evoked Cortical Responses to Linear Frequency Ramps of a Continuous Pure Tone
Authors: Arlinger S. D. , Jerlvall L. B. , Ahrén T. , Holmgren E. C.
Published: December 2008

Arlinger, S. D., L. B. Jerlvall, T. Ahrén and E. C. Holmgren. Slow evoked cortical responses to linear frequency ramps of a continuous pure tone. Acta physiol. scand. 1976. 98. 412–424.

Slow evoked cortical potentials from ten young normal‐hearing subjects have been recorded as responses to linear frequency ramps of a continuous pure tone. Frequency changes from 10 to 500 Hz were studied; the rate of frequency change was varied from 0.02 to 50 kHz/s while the duration of the change was varied from 10 to 500 ms. The rate of frequency change was shown to have the greatest bearing on the responses except for frequency ramp durations below 50 ms and frequency changes below 50 Hz. The base frequencies (250–4000 Hz) and sound levels (20–80 dB HL) exerted an influence on the evoked responses that was qualitatively similar to their influence on behavioral thresholds. The direction of the frequency sweep had no significant influence on the evoked responses. A functional model is proposed in which the time derivate of the signal frequency is integrated with an adaptable integration time that is controlled by the rate of the frequency change.
Influence of Intraocular Colchicine and Vinblastine on the Cat Iris
Authors: Hahnenberger Rudolph W.
Published: December 2008

Hahnenberger, R.W.Influence of intraocular colchicine and vinblastine on the cat iris. Acta physiol. scand. 1976.98. 425–432.

The effect of intravitreally injected colchicine (100 μgand 300μg) and vinblastine (100μg) on function and sensitivity of the cat iris was studiedin vivo. Both antimitotics caused the same effects: The sensitivity to touch of the cornea disappeared after the third day. The normal sensitivity recovered, but after 1 month there was still an anesthetic island in the center of the cornea. The consensual light reflex from the injected to the normal eye declined markedly between 12 and 24 h and was abolished after 4 days. The consensual light reflex from the normal to the injected eye decreased with a similar time course and was completely abolished or strongly reduced after 4–5 days. The function of the sphincter pupillae in the injected eye was reestablished after one month. The affected iris became supersensitive to both pilocarpine and norepine‐phrine. The degree of super sensitivity in the cholinergic system was closely and inversely related to the degree of impaired function. The function of the dilatator pupillae could not be tested. The observed phenomena were most likely due to inhibition of exoplasmic flow in the nerves supplying the iris and cornea.
The Evaluation of Synthetic Oxygen Carriers by Perfusion of Isolated Rat Liver
Authors: Nováková Vera
Published: December 2008

Nováková, V. The evaluation of synthetic oxygen carriers by perfusion of isolated rat her. Acta physiol. scand. 1976. 98. 433–439.

The perfluorochemical FC‐80 emulsion was added as oxygen carrier to a synthetic medium used for perfusion of isolated rat liver. The oxygen carrying function of FC‐80 was evaluated from measurements of serum albumin synthesis and incorporation of 14C‐lysine into the proteins in the medium. The effect of changes in flow rate of the medium on the evaluation of FC‐80 was investigated. The results show that there is a correlation between the serum protein synthesis and the oxygen supply only when the liver is hypoxic. In hypoxic liver both the addition of FC‐80 and the increase of the flow rate improve the oxygen supply which is indicated by increased serum protein synthesis. The effect of FC‐80 on serum protein synthesis is different at different flow rates. For the evaluation of the oxygen carrying function of FC emulsions from the metabolic function of the liver such a flow rate and affluent PO are optimal in which the FC is a limiting factor for sufficient oxygen supply.
Biosynthesis of Cadaverine in Mice under the Influence of an Anabolic Steroid
Authors: Henningsson Stig , Person Lo , Rosengren Elsa
Published: December 2008

Henningsson, S., L. Persson and E. Rosengren. Biosynthesis of cadaverine in mice under the influence of an anabolic steroid. Acta physiol. scand. 1976. 98. 445449.

The content of cadaverine (1,5‐diaminopentane) in the kidney and urine was investigated in mice treated with the anabolic steroid Durabolin (nandrolone phenpropionate). After administration of this steroid cadaverine was found in the kidneys, whereas this amine could not be detected in the kidney of controls. The urinary excretion of cadaverine was elevated 50 times after Durabolin administration. An enzyme catalyzing the formation of cadaverine from lysine was shown for the first time to be present in mammalian tissue, namely in the kidney of mice after Durabolin administration.
Improved Left Ventricular Performance by the Transmission of Pulse Waves through the Pulmonary Vascular Bed
Authors: Piene Hroar
Published: December 2008

Piene, H. Improved left ventricular performance by the transmission of pulse waves through the pulmonary vascular bed. Acta physiol. scand. 1976. 98. 450–456.

The influence on left ventricular performance of pulsewaves transmitted through the pulmonary vascular bed was studied in a cat lung preparation with the right heart bypassed by a pulsatile blood pump. The pump worked at a frequency slightly different from the intrinsic heart rate; transmitted pulse waves were thereby forced to arrive the left atrium at different phases of the left heart cycle. Slow fluctuations of left atrial pressure, left ventricular systolic pressure and left ventricular dP/dt were observed. Left ventricular systolic pressure and left ventricular dP/dt were maximum when the transmitted pulsewaves arrived left atrium just prior to the atrial contraction. The observed variation in left ventricular systolic pressure was found to be directly dependent on the magnitude of pulsatile hydraulic power transmitted to the left atrium.
Degeneration Secretion and Noradrenaline Disappearance in Rat Salivary Glands Following Proximal or Distal Axotomy
Authors: Almgren O. , Dahlström A. , Häggendal J.
Published: December 2008

Almgren, O., A. Dahlströmand J. Häggendal.Degeneration secretion and noradrenaline disappearance in rat salivary glands following proximal or distal axotomy. Acta physiol. scand. 1976.98. 457–464.

The noradrenaline (NA) content and the degeneration secretion of saliva were studied in rat salivary glands, following proximal or distal sympathetic denervation. Proximal denervation was obtained by removal of the cervical superior ganglion, which left a long stump of adrenergic axons attached to the gland. Distal denervation was achieved by crushing the perihilar tissue, including the adrenergic axons, close to the gland, leaving only short axon stumps connected with the gland. Onset of both NA decrease and degeneration secretion occurred first in the distally denervated glands and about 2 h later on the proximally denervated sides. Except for the delay of 2 h the pattern of NA decrease and saliva secretion was similar after the two denervation procedures. The length of the attached axon stumps was estimated to be about 15–20 mm longer on the proximally denervated side. Therefore, the delay of 2 h caused by this length of axons corresponds to the proximo‐distal intra‐axonal transport distal to the “axotomy” of some protecting factors at the rate of 8–10 mm/h. Onset of degeneration secretion was observed between 11 and 12 h after proximal denervation when the NA content was decreased by about 10 9:. The maximum of saliva secretion occurred about 14 l/2 h after denervation when only 45 % of the NA remained in the gland. The correlation between the degeneration secretion of saliva and the decrease in NA probably was due to 1) the amount of NA leaking from degenerating nerve terminals, and 2) the inactivation of this escaped NA by the re‐uptake mechanism in the membrane of still intact nerve terminals.
On the Elicitation of the Diving Responses in Ducks
Authors: Blix Arnoldus Schytte , Rettedal Arne , Stokkan Karl‐Arne
Published: December 2008

Blix, A. S., A. Rettedal and K.‐A. Stokkan. On the elicitation of the diving responses in ducks. Acta physiol. scand. 1976. 98. 478–483.

Peripheral receptors signalling in both the 3 main divisions of the trigeminal nerves and in the glosso‐pharyngeal nerves are most likely involved in the onset of the apnea in diving ducks. Since the response also takes place when ducks are submerged in mercury, these peripheral receptors are hardly specific to water. Neither any of the 3 main groups of trigeminal, nor the glossopharyngeal receptors are alone responsible for the initiation of the apnea. Most likely the apnea takes place when the total impact on the ‘respiratory centre’ in the brain exceeds a certain treshold value, due to activation of a certain number of both trigeminal and glossopharyngeal peripheral receptors. However, even very local stimulation of the glottal area invariably evoked apnea, indicating a higher density of receptors there than for example on the beak or in the nares. This idea is supported by the fact that not even heavy rain evokes any response at all. It is unlikely that the cardiovascular adjustments displayed by diving ducks are directly coupled to the apnea response (ie. to stimulation of peripheral receptors). Rather they are supposed to be components in orienting and chemoreceptor reflexes.
Effects of Volleys in Cortico‐spinal Tract Fibres on Ventral Spino‐cerebellar Tract Cells in the Cat
Authors: Fu T.‐C. , Jankowska E. , Tanaka R.
Published: December 2008

Both excitation and inhibition has been found in cells of origin of the ventral spino‐cerebellar tract (VSCT) to be evoked by volleys in cortico‐spinal fibres. The earliest EPSPs and IPSPs had features of disynaptically evoked postsynaptic potentials; these were, however, found only in a small proportion of cells and polysynaptic EPSPs and IPSPs were dominating. Postsynaptic potentials evoked in VSCT cells from primary afferents were effectively facilitated by cortico‐spinal volleys. The cortico‐spinal effects on VSCT cells may thus well be mediated by the same interneurones which mediate their excitation or inhibition from the periphery and which could evoke similar postsynaptic potentials in motoneurones. Generally all the observations are in keeping with the hypothesis (Lundberg 1971) that VSCT cells monitor transmission through interneurones interposed in various reflex paths to motoneurones.
Effect of “Vein Pump” Activation upon Venous Pressure and Blood Flow in Human Subcutaneous Tissue
Authors: Henriksen O. , Sejrsen P.
Published: December 2008

The effect of “vein pump” activation upon superficial venous pressure and blood flow in human subcutaneous adipose tissue was studied in 6 normals and 2 patients with venous insufficiency. Blood flow in subcutaneous tissue was measured at the lateral malleolus by the local 133Xenon washout technique. with the subject placed in a supine position. During passive lowering of the leg blood flow decreased 50 per cent and total vascular resistance increased 136 per cent. Activation of the vein pump by continuously tipping the foot up and down caused a decrease in venous pressure of 5 mmHg in horizontal position. Venous pressure increased only by 8 mmHg when the leg was lowered during exercise. In this situation blood flow remained constant corresponding to an increase in vascular resistance of 42 per cent. However increasing venous pressure to 28 mmHg by venous stasis in the lowered leg during exercise caused an additional increase in vascular resistance of 82 per cent. In the patients with venous insufficiency exercise did not prevent the decrease in blood flow during lowering of the leg. Hence venous pressure elevation of 25 mmHg or more caused an additional increase in vascular resistance in subcutaneous tissue, “vasoconstrictor response”. It is concluded that this “vasoconstrictor response” depends on a vasoconstrictor impulse transmission from veins to arterioles, veno‐arteriolar reflex.
Regulation of Salivary Kallikrein Secretion in the Rat Submandibular Gland
Authors: ØRstavik Torill B. , Gautvik K. M.
Published: December 2008

Unstimulated pairs of rat submandibular glands were compared with regard to their wet weight, total protein content and kallikrein activity quantitated by Bz‐Arg‐OEt‐esterase and kallikrein antigenic activity. Paired glands from the same animal were found to be comparable, whereas differences from one animal to another were considerable. One of two paired glands was extirpated and used as control, and the other was subsequently subjected to stimulation. Salivary secretion was induced parasympathomimetically (intraperitoneal injections of pilocarpine; perfusion with acetylcholine and electrical stimulation of the ductal nerve plexus near the gland hilus) or sympathomimetically (cervical sympathetic nerve stimulation with or without administration of α or β‐adrenergic blocker; perfusion with epinephrine, norepinephrine or isoproterenol). The effect was studied by measuring the change in total gland kallikrein content and by quantitation of kallikrein in saliva. A small secretion of kallikrein was always observed. However, oc‐adrenergic stimulation was 40 and 1500 fold more effective in releasing kallikrein than β‐adrenergic and parasympathomimetic stimulation, respectively. Also, significantly more kallikrein was released by β‐adrenergic than parasympathomimetic stimulation. Immunohistochemistry confirmed the observed depletion of kallikrein following α‐adrenergic stimulation. No alteration in kallikrein localization was observed in stimulated glands.
Deuterium Induced Extinction of ADH‐release in Response to Intracerebroventricular Infusions of Hypertonic NaCl and Angiotensin
Authors: Rundgren M. , Leksell L. G. , Lishajko F. , Andersson B.
Published: December 2008

Infusions (20μl/min) of hypertonic (0.3 M) NaCl and angiotensin 11 (1 ng/kg min‐1)in isotonic (0.15 M) NaCl were made for 1 h in the hydrated goat during fully developed water diuresis. Either H2O or deuterium (D2O) was used as solvent. A pronounced antidiuretic response, outlasting the infusion period by 30 min or more, was seen when the substances were dissolved in H2O. Only a weak inhibition of the water diuresis, which was extinguished during the infusion period, was obtained when D2O was used as the solvent. The infusion of 0.3 M NaCl/H2O invariably induced drinking in one of the goats, which, however, showed no drinking response to the infusions of 0.3 M NaCl/D2O. The possibility is discussed that D2O (perhaps by‐its inhibitory effect on (Na+‐K+)‐ATPase activity) reduced the sensitivity of juxtaventricular receptors regulating ADH‐release and water intake.
Shortlasting Increase in the Synthesis and Utilization of Noradrenaline due to Axotomy‐Induced Irritation
Authors: Andén Nils‐Erik
Published: December 2008

The synthesis and the utilization of noradrenaline in the caudal and cranial part of intact and sectioned rat spinal cords were determined at 20 h or for 30 min ‐ 2 h after an operation. The synthesis and the utilization of noradrenaline in the caudal pari of spinal cords transected 20 h previously were retarded as compared to those in the cranial part of sectioned cords or in the caudal part of intact cords. The synthesis of noradrenaline was stimulated in the caudal and cranial part of the spinal cord when measured for 30 min after a transection. The utilization of noradrenaline in the spinal cord caudal to a transection was not decelerated during 2 h after an operation. Local application of lidocaine to the cord prior lo the cut changed the synthesis and the utilization of noradrenaline in both parts of the spinal cord to values similar to those obtained 20 h after the operation. Transection of the spinal cord might stimulate the synthesis and the utilization of noradrenaline by a shortlasting mechanical irritation of neurons cut by the lesion.
Mechanical, Electrical, and Biochemical Effects of Hypoxia and Substrate Removal on Spontaneously Active Vascular Smooth Muscle
Authors: Hellstrand Per , Johansson Börje , Norberg Karin
Published: December 2008

Effects of hypoxia and glucose‐free solution on the isolated rat portal vein were studied. Decrease of extracellular Po2below 50 mm Hg caused graded inhibition of spontaneous mechanical activity; below 7 mm Hg. inhibition was complete in most preparations. Contracture force of depolarized portal vein was less sensitive to decreases in Po2. Responses to noradrenaline at all concentrations were markedly depressed at extreme hypoxia. Sucrose‐gap experiments showed that hypoxia reduced the spontaneous electrical spike discharge. Mean tissue contents of PCr, ATP and glycogen (expressed as glucose) were 3.02, 2.47 and 5.07μmol/g cell wt. in spontaneously active control muscles and 1.07, 1.65 and 1.83 after 20 min anoxia. Physiological variations in Po2may influence myogenic activity of vascular smooth muscle largely through an action at the membrane level and this mechanism may participate in local blood flow control. Calculations indicated that the graded response to hypoxia in the present in vitro experiments was not due to diffusion limitation. Spontaneous mechanical activity was relatively well maintained even after prolonged exposure to glucose‐free solution, whereas the responses to K1and noradrenaline were markedly suppressed. Electrophysiological recordings during spontaneous activity indicated desynchronization and impaired conduction. PCr and ATP were maintained at control levels and glycogen reduced by 50 per cent after 2 h in glucose‐free medium. Indications of the use of amino acids (glutamate) as substrate under these conditions were obtained.
Anaerobic Performance Capacity in Athletes
Authors: Komi Paavo V. , Rusko Heikki , Vos Jan , Vihko Veikko
Published: December 2008

Anaerobic performance characteristics of the whole body and at muscle tissue level were studied in 89 athletes and 31 reference subjects. The main parameters were vertical velocity during running up the stairs, maximal isometric force of leg extensor muscles, blood lactate concentration after maximal treadmill running test, percentage of fast twitch muscle fibers (% FT fibers), lactate dehydrogenase (LDH) and creatine phosphokinase (CPK) activity in vastus lateralis muscle. These parameters tended to divide the athletes and their sport events into neuromuscular, anaerobic and aerobic types. The specific needs of the different sport events might have masked the expected characteristics of energy and power utilization. However, a high percentage of FT fibers might be a prerequisite for a successful athlete in certain neuromuscular‐anaerobic type events (“power events”). The main parameters describing the anaerobic performance capacity of the whole body (vertical velocity, leg force, blood lactate) were found to be related to muscle fiber composition (% FT fibers). The running velocity rather than muscle strength seemed to be more influenced by activity of enzymes LDH and CPK.
Tail Artery Response to Sound in the Unanesthetized Rat
Authors: Borg E.
Published: December 2008

Arterial pulsations have been recorded indirectly from the surface of the rat's tail. Slight heating of restrained unanesthetized rats produces vasodilatation and large amplitude pulsations that are influenced by sensory stimuli, in this case, sound. The surface‐recorded pulse volume was found to be proportional to pulse pressure, indicating vasoconstriction as the cause of the decline of the pulse amplitude. A one‐second noise burst elicited vasoconstriction, the duration of which was proportional to sound level and occurred as low as at hearing threshold. Under the specified conditions, reproducibility was good with no significant habituation both within session, and between sessions with a one week interval. The warming of the rats was found to be critical for the sound‐elicited reactions; responses were obtained only within a narrow, individual temperature‐range. The possibilities of using tail vasoconstriction for evaluation of hearing was pointed out, as well as for studies of noise effects on peripheral circulation.
Regional Blood Flow in the Left Ventricular Wall of Dogs with a Graded Coronary Artery Stenosis
Authors: Bagger Henning
Published: December 2008

Blood flow in the circumflex branch of the left coronary artery was recorded by electromagnetic flowmeter. In the area supplied by this branch vasodilatation was produced by progressive constriction until the diastolic reactive hyperemic response to 10 s occlusion disappeared (“optimum” stenosis). This degree of stenosis was accompanied by a 20% decrease in diastolic circumflex flow, while systolic flow remained unchanged. The distribution of blood flow in the left ventricular free wall was evaluated at “optimum” stenosis by counting activity in tissue blocks following bolus injection of Xe‐133 into the aortic root. When Xe‐133 was injected immediately after occlusion of the left anterior descending branch the Xe‐133 concentration of the endocardial part of the area supplied by the circumflex branch was about half the concentration in the epicardial part. The concentrations in the two parts did not, however, differ significantly when occlusion of the left anterior descending branch was omitted. This indicates that the endocardial blood flow reserve is lower than the epicardial, and that, yet, a preferential fall in blood flow in the endocardial part of a post‐stenotic area can be rapidly eliminated when blood supply from a neighbouring artery is available.
Bronchial Effects of Some Prostaglandin E and F Analogues
Authors: Strandberg Kjell , Hedqvist Per
Published: December 2008

The effects of some analogues of PGE1, PGE2and PGF2α, rendered less accessible to the action of prostaglandin dehydrogenase by having methyl groups at carbons 15 and/or 16, or a phenyl group at carbon 17, on the tracheobronchial insufflation pressure in guinea pigs and on the tone of isolated human bronchi were investigated. Regardless of route of administration, i.v. injection or aerosol administration, PGE1,16,16‐dimethyl‐PGE1, PGE2, the methyl esters of 15(R)15‐methyl‐PGE2and 15(S)15‐methyl‐PGE2, 16,16‐dimethyl‐PGE2and its methyl ester, and 17‐phenyl PGE2all produced a dose‐dependent inhibition of the histamine‐induced increase in insufflation pressure and a fall in systemic blood pressure in the anesthetized guinea pig. Although the duration of action of the PGE‐analogues was longer than that of the parent compounds, none of them was more potent with regard to the peak effect produced on insufflation pressure. Of the PGF2αanalogues studied, 16,16‐dimethyl‐PGF2αwas the most potent compound, in decreasing rank order followed by 15(S)15‐methyl‐PGF2α, 17‐phenyl‐PGF2αand PGF2α, in eliciting an increase in insufflation pressure on i.v. injection. On aerosol administration, only 16,16‐dimethyl‐PGF2αcompound was more potent than PGF2αOn isolated human bronchi, PGE1and PGE2were consistently relaxant, although in some expts. the relation to PGE2was followed by constriction. The 16,16‐dimethyl analogues of PGE1and PGE2were consistently bronchoconstrictor whereas the effects of the other PGE–analogues were weak and inconsistent. In comparison with the bronchorelaxant β2‐adrenoceptor stimulating compounds, the PGEs and PGE‐analogues studied do not have any outstanding features and may even imply a risk in clinical practice.
Muscle Spindle Activity in Man during Standing
Authors: Burke David , Eklund Göran
Published: December 2008

In standing human subjects, muscle spindle activity was recorded from peroneal nerve fascicles innervating anterior compartment muscles. Provided that the receptor‐bearing muscle remained relaxed, the basal activity and responses to stretch seen in multi‐unit and single unit afferent recordings were stable and not altered by eye‐closure or assistance to balance. The discharge frequencies of single afferent fibres were similar to those recorded at comparable muscle lengths in relaxed reclining subjects. By analogy to findings in reclining subjects, these results suggest that, during standing, the background fusimotor drive to relaxed muscles is negligible. Backward body sway can induce a sway‐stabilizing reflex contraction in the muscles of the anterior compartment. Such reflex contractions were accompanied by increased muscle spindle activity, the intensity of which appeared to be related to the intensity of the skeletomotor contraction. When balance was assisted by holding a support, swaying movements of similar or greater amplitude and velocity did not produce reflex activity, and the spindle response was of low frequency. It is concluded that the sway‐stabilizing reflex contraction operates in alpha‐gamma linkage, and that these contractions are not generated by segmental stretch reflex pathways.
Glycogen Synthetase and Phosphorylase Activity in Slow and Fast Twitch Skeletal Muscle Fibres in Man
Authors: Piehl Karin , Karlsson Jan
Published: December 2008

Glycogen synthetase (I + D) and phosphorylase (á+b) activity was determined in human skeletal muscle biopsies with different muscle fibre composition and in dissected and pooled batches of the two main muscle fibre types: slow twitch (ST) and fast twitch (FT), respectively. Glycogen synthetase (I + D) activity remained unchanged as the per cent of FT fibres increased, but phosphorylase (á+b) activity was found to increase. A similar activity pattern was found in dissected and pooled FT fibres as compared to ST fibres, i.e. the same glycogen synthetase activity but heightened phosphorylase activity.
Comparative Effects of Adrenaline and Felypressin (Oetapressin) on Consecutive Sections of the Vascular Bed in Canine Adipose Tissue
Authors: Burcher Elizabeth , Olgart Leif , Gazelius Bertil
Published: December 2008

Blood flow and tissue volume were recorded in the isolated canine subcutaneous adipose tissue, enclosed in a plethysmograph. Adrenaline and felypressin (oetapressin) were infused intra‐arterially at doses producing a blood flow reduction of approximately 60%. Adrenaline (4.6–23 ng/min) caused an initial reduction in tissue volume, indicating a constriction of capacitance vessels. Octapressin (0.46–9.2 ng/min) had no effect on tissue volume. Neither adrenaline or octapressin caused appreciable filtration or absorption, suggesting that the pre‐ to postcapillary resistance ratio remained unchanged. In contrast to sympathetic stimulation and noradrenaline, adrenaline significantly reduced the capillary filtration coefficient (CFC) by 34%, the change in CFC being related to the flow reductions, while octapressin did not reduce CFC significantly. On the basis of these results it is suggested that the constrictor effect of adrenaline on precapillary sphincter sections and on capacitance vessels is greater than that of octapressin in doses producing similar flow reductions.
“Emotional” Bradycardia: A Telemetry Study on Incubating Willow Grouse (Lagopus lagopus)
Authors: Gabrielsen Geir , Kanwisher John , Steen Johan B.
Published: December 2008

Although heart rate in most species reflects the metabolic state of the animal, emotional stimuli may act as strong modifying agents. This has been experienced by arctic explorers challenged by polar bears (Nansen 1898) and by TV‐watchers during exciting shows. It is also noticed in animals under a variety of experimental conditions (Folkow and Neil 1971). Thus, in some animals, cortico‐hypothalamic activity may strongly influence the cardiovascular response pattern in certain situations. Inexperienced parachuters, for instance, may more than double their heart rate, without any increase in metabolism, prior to a jump (Ursin, Baade and Levine 1977). Oppossums and deerkids, on the other hand, display pronounced cardiac retardation, much reduced breathing rate and temporary Joss of consciousness (“playing dead”‐reaction) when exposed to danger (Folkow and Neil 1971). In this context it is noteworthy that the cardiac response to danger in arctic explorers does not involve loss of consciousness. This was well demonstrated when H. Johansen from his supine position underneath a hungry bear exclaimed to his companion, F. Nansen: “You must look sharp it you want to be in time” (Nansen 1898).
Prostaglandin E2‐ and α‐ or β‐Adrenoceptor Mediated Interferences with 3H‐Noradrenaline Secretion from Human Vasomotor Nerves: Comparison between Effects on Omental Arteries and Veins
Authors: STJÄRNE LENNART , BRUNDIN JAN
Published: December 2008

In earlier work with human vasomotor nerves (Stjärne and Gripe 1973) it has been shown that the inhibition of 3H‐NA secretion by exogenous N A, and the enhancement caused by the α‐adrenoceptor antagonist phentolamine, occur even after blocking formation of prostaglandin E2 (PGE2) with 5,8,11,14‐eicosatetraynoic acid (ETA). This shows that at least part of the α‐adrenoceptor mediated control of NA secretion is independent of (not mediated by) endogenous PGE2. In the same paper it was also shown that the inhibitory effect of exogenous PGE2 on 3H‐NA secretion persists in the presence of phentolamine, indicating that exogenous PGE2 acts on a target in the nerves different from that of NA (Stjärne 1973).
Muscle Adaptation to Extreme Endurance Training in Man
Authors: Jansson E. , Kaijser L.
Published: December 2008

To evaluate the effect of extreme endurance training on muscle fibre composition and activities of oxidative enzymes in different fibre types biopsies were taken from vastus lateralis, gastrocnemius and deltoideus of elite orienteers. Comparisons were made between the (trained) leg muscles and the (relatively untrained) arm muscles, and with leg muscles of 16–18 years old boys. The orienteers had the same percentage type I fibres in vastus lateralis and gastrocnemius as in deltoideus, but higher percentage type I fibres in vastus lateralis compared with the controls. The similarity between trained and untrained muscle in the orienteers suggests that training had not caused the high percentage type I fibres which rather might be the result of selection of individuals with the best prerequisites for high oxidative capacity. However, the distribution of type II subgroups in the leg muscles of the orienteers differed from both their own deltoideus and leg muscles of the controls, the relationship IIA/IIB being altered in favour of the more oxidative IIA. The leg muscles of the orienteers also showed an increased occurrence of the normally rare IIC fibre. These latter findings point at the possibility of a training induced alteration in the subgroup pattern. Unlike in the controls there was no significant difference in succinate dehydrogenase activity, measured in single fibres, between type I and II fibres in gastrocnemius of the orienteers. Thus, type II fibres have the ability metabolically to adapt to high oxidative demands. This might to some extent be mediated by a conversion from IIB to IIA form.