bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in the Cell Volume of Isolated Vascular Smooth Muscle in Response to Reduced Osmolarity
Authors: Jonsson Olof
Published: December 2008

The intracellular water of smooth muscle from the rat portal vein decreases on exposure to hyperosmotic solutions to an extent expected for perfect osmometers (Arvill, Johansson and Jonsson 1969). The purpose of the present study has been to investigate the variations in cell water produced by reductions in extracellular osmolarity.

After 15 min of incubation at 37° C in a solution which was 105 mOsm/l hypo‐osmotic (minus 60 mmoles NaCl/1) compared to normal Krebs solution, the intracellular water increased by 14 ± 7 per cent in muscles stretched to their in situ length and by 35 ± 9 per cent in unstretched muscles. When the same procedures were performed at 1° C, a temperature that considerably reduced the mechanical response to hypo‐osmolarity, the volume of the cell water in the stretched and unstretched muscles increased to approximately the same extent (40 and 35 per cent respectively). These results suggest that the active tension development associated with excitation at low osmolarity opposed the swelling of the muscle cells in the stretched muscles at 37° C while the passive tension per se was less important for the degree of swelling. However, had the smooth muscle cells behaved like perfect osmometers the increase in cell water at this reduction in osmolarity would have been 58 per cent. The difference between this value and those obtained in situations where the active tension development was prevented might be accounted for by a loss of intracellular ions. Such a loss of ions was clearly demonstrated in stretched muscles at 37° C which showed the smallest degree of swelling. This suggests that muscle cells, when unable to adapt their intracellular osmolarity to a reduced extracellular tonicity by swelling, do so by dropping a fraction of their intracellular ions.
Hyperosmolality and Vasodilatation in Human Skeletal Muscle
Authors: Lundvall Jan , Mellander Stefan , White Thomas
Published: December 2008

Exercise of the forearm muscles in man was found to cause a considerable increase of the osmolality in the venous effluent but no osmolar change in arterial blood, thus indicating a regional hyperosmolality in the working muscles. There was a relation between the degree of hyperosmolality during work and the extent of the exercise hyperemia (determined immediately after cessation of exercise). Experimental hyperosmolality of similar magnitudes, produced in the resting skeletal muscle by intra‐arterial infusion of hypertonic solutions of glucose, xylose, or mannitol, invariably elicited a dilatation of the resistance vessels, whereas there was no significant effect of isotonic infusion. Vascular resistance tended to decrease progressively with increasing osmolality. Furthermore, intramuscular deposits of Xe133in the resting muscle were cleared more rapidly when the tracer was dissolved in hypertonic than in isotonic medium, indicating a hyperemia response also when the hyperosmolality primarily involved the extra‐vascular space. The results are discussed in relation to previous studies of the effects of hyperosmolality on skeletal muscle circulation in anesthetized animals and on vascular smooth musclein vitro.The conclusion was reached that hyperosmolality can be one factor contributing to exercise hyperemia in man.
The Effect of Acetazolamide upon Tissue Concentrations of Bicarbonate, Lactate, and Pyruvate in the Rat Brain
Authors: Kjällquist A. , Nardini M. , Siesjö B. K.
Published: December 2008

The effect of various doses of acetazolamide upon acid‐base parameters in brain tissue, cisternal CSF and arterial plasma was studied in rats, anesthetized with phenobarbital or nitrous oxide. The results confirmed older findings that carbonic anhydrase inhibition increases the CSF/plasma ratio for bicarbonate, and decreases the corresponding chloride ratio, and showed that the CSF pH remains unchanged during at least 6 hrs in spite of a marked plasma acidosis. The tissue bicarbonate was found to be significantly, but transiently, increased, and since the CSF bicarbonate was essentially unchanged, the increase in bicarbonate must have occurred in the intracellular phase,i.e.an alkaline shift in the cells. However, both the lactate and the pyruvate concentrations in the tissue were decreased after acetazolamide, suggesting an acidosis. It is discussed if these controversial findings indicate that caibonk anhydrase inhibition gives rise to a carbonic acid acidosis in the brain.
Effects of Some Metabolic Co‐Factors and Inhibitors on Transmitter Release and Uptake in Isolated Adrenergic Nerve Granules
Authors: Euler U. S. von , Lishajko F.
Published: December 2008

Various nucleotides and metabolic inhibitors have been tested on the release, reuptake and net uptake of noradrenaline (NA) in isolated splenic nerve granules. Cytidine, inosine, and uridine triphosphate facilitated uptake of NA to a similar degree as adenosine diphosphate but less than adenosine triphosphate. Cyclic AMP had no effect.

Various inhibitors of the respiratory chain and oxidative phosphorylation (rotenone, chlorpromazine, antimycin and oligomycin) inhibited both release and uptake of NA at 10–3–10–4M. Atractylate had no action at 10–3M. Cyanide and azide at 10–3M had no or a slight action only.

The uncouplers dinitrophenol, carbonyl cyanidem‐chlorophenyl hydrazone, desaspidin, and pentachlorphenol all increased the release rate of NA from granules and inhibited reuptake.

The results suggest that the ATP facilitated uptake process requires electron transport and that the ability of the granules to retain bound NA is dependent on an energized state of the system. At least certain steps of electron transport‐coupled phosphorylation occurring in mitochondria appear to be involved in amine release and uptake in granules.
Effects of Slow Infusions of KCl into the 3rd Brain Ventricle
Authors: Olson Kerstin
Published: December 2008

During slow (7.5 μl/min) infusions of strongly hypertonic (0.4–0.85 M) KCl solutions into the anterior part of the 3rd brain ventricle of the goat, a series of behavioural reactions developed (strong thirst and polypnea, later on accompanied by hyperphagia and minor rage reactions). Similar infusions of less hypertonic or isotonic KCl also induced thirst and polypnea but no hyperphagia. Natriuresis and a temporary inhibition of the water diuresis of hydrated animals were other effects elicited by the intraventricular infusions of both isotonic and hypertonic KCl. The effects of the KCl infusions on the water and electrolyte balance were compared to those obtained by similar infusions of equimolar NaCl in the same animal.

It is concluded that a rather selective, non‐specific stimulation of diencephalic mechanisms may be obtained by slow infusions of KCl into the anterior part of the 3rd ventricle. The experiments have given no evidence that an elevated K+ concentration in the diencephalic region stimulates renal K+ excretion specifically.
Studies on the Relaxing Actions Mediated by Stimulation of Adrenergic α‐and β‐Receptors in Taenia Coli of the Rabbit and Guinea Pig
Authors: Son Rolf Anders , Mohme‐Lundholm Ella
Published: December 2008

In experiments on taenia coli from rabbits, a study was made of the mechanisms whereby catecholamines induce a relaxing effect. In a low concentration (≤2.1 × 10–6g/ml), l‐phenylephrine selectively stimulated adrenergic a‐receptors; this effect was blocked completely by the adrenergic α‐blocking agent dibenamine. In a low concentration (≤ 3.7 × 10–8g/ml), 1‐isoprenaline selectively stimulated β‐receptors; this effect was blocked completely by the adrenergic β‐receptor blocking agent sotalol. In higher concentrations, phenylephrine and isoprenaline stimulated both adrenergic α‐and β‐receptors; their relaxing effect could only be blocked completely by a combination of dibenamine and sotalol. In taenia coli from rabbits, the threshold concentration for β‐receptor‐mediated relaxation was lower than that for relaxation induced via a‐receptors; in taenia coli from guinea pigs the reverse was found. The relaxant effect induced via adrenergic a‐receptors was blocked selectively by factors such as cold treatment, digitalis glycosides, desoxycorticosterone, which could be assumed to decrease the ionic gradients of K+ and Na+ across the cell membrane or reduce its ionic permeability. — On successive reduction of the carbohydrate reserves of the muscle, the relaxation induced via adrenergic β‐receptors was inhibited more rapidly than that induced via α‐receptors. Theophylline and puromycin, which inhibit the enzymatic hydrolysis of cyclic AMP, potentiated selectively the β‐receptors mediated relaxation.
Effects of Gastric and Jejunal Juice Extracts on Gastric Acid Secretion
Authors: Semb Lars S.
Published: December 2008

The specificity of inhibition of i.v. injected extracts prepared from the gastric antral juice of dogs was studied by comparison with extracts prepared from canine fundic and jejunal pouches. The extracts were prepared by dialysis against water and lyophilization, and injected in doses of 1 mg/kg b.w. into Heidenhain pouch dogs secreting at a steady state from constantly infused histamine. Extracts of antral juice (22 expts. in 5 dogs) were found to inhibit gastric secretion in 17 expts. (average 63.6%), while in 4 expts. there was stimulation of gastric secretion (average 57%). Extracts of fundic juice were tested in 21 expts. in 4 dogs, and showed inhibition in 10 (average 50.4%) and stimulation in 10 expts. (average 54.8%). The extracts obtained from jejunal secretions were tested in 15 expts. on 3 dogs, and showed inhibition of gastric acid secretion in 9 expts. (average 50.6%), while in 4 expts. there was significant stimulation of the secretion (47.7%). Rectal temperature was increased more than 0.5° C in 8 of the experiments with antral juice extracts, in 4 with fundic extracts, and in 7 with jejunal extracts. Inhibition or stimulation was observed in these experiments. It is concluded that dialyzed and lyophilized extracts from gastrointestinal secretions contain substances that either stimulate or inhibit gastric secretion. The inhibitory effect could not be completely explained by pyrogenicity of extracts.
Structure and Function of the Tactile Hair Receptors on the Cat's Foreleg
Authors: Nilsson Bengt Y.
Published: December 2008

The cat's carpal sinus hairs are shown to be supplied by free nerve endings and Merkel cellneurite complexes. Using a mechanical stimulator permitting hair displacements at varying rates and amplitudes, dynamic and static responses were analyzed. Most units respond to static displacement by slowly adapting discharges which after an initial decline in frequency attain a steady state whose frequency is related to the displacement amplitude by a power function. The frequency in the dynamic phase rises with the rate of rise, increasing during the movement and decreasing as the final plateau is attained. The dynamic response is related to the rate of rise by a power function. Most of these slowly adapting receptors respond most effectively to proximal hair movements. Movement of one hair elicits responses in several units which may have reciprocal directional sensitivity. Each fiber supplies only one hair. Effects of pilomotor muscle activation on the afferent inflow were demonstrated in experiments concerning the possible existence of an efferent regulating mechanism. Above a minimum velocity some receptors discharged in the dynamic phase, being silent in the static phase. These rapidly adapting receptors responded to movements in all directions and displayed off responses. Fiber conduction velocities were determined.
Studies on Central Regulation of Secretion of Antidiuretic Hormone (ADH) in the Goat
Authors: Olsson Kerstin
Published: December 2008

A further analysis was made of the antidiuretic response to infusions of NH4C1 into the 3rd brain ventricle of hydrated goats. The response was obtained in the absence of “osmotic” stimulation, but was evidently due to a release of antidiuretic hormone (ADH), since it disappeared after the induction of experimental diabetes insipidus. No antidiuresis was obtained by infusions of hypertonic saccharose into the 3rd ventricle. The activation of heat dissipation mechanisms by local warming of the preoptic/anterior hypothalamic region was not associated with any inhibition of the water diuresis. However, profound local cooling of this part of the brain induced a release of ADH in hydrated animals. The possibility is discussed, that this effect of local brain cooling may be due to a reduction of a neural inhibition, normally exerted on the ADH release.
The Effect of Asphyxia upon the Lactate, Pyruvate and Bicarbonate Concentrations of Brain Tissue and Cisternal CSF, and upon the Tissue Concentrations of Phosphocreatine and Adenine Nucleotides in Anesthetized Rats
Authors: Kaasik A. E. , Nilsson L. , Siesjö B. K.
Published: December 2008

Kaasik, A. E., L. Nilsson and B. K. Siesjö. The effect of asphyxia upon the lactate, pyruvate and bicarbonate concentrations of brain tissue and cisternal CSF, and upon the tissue concentrations of phosphocreatine and adenine nucleotides in anesthetized rats. Acta physiol. scand. 1970. 78. 433–447.

The effect of asphyxia upon the lactate, pyruvate and bicarbonate concentrations of brain tissue and cisternal CSF, and upon the tissue concentrations of phosphocreatine, ATP, ADP and AMP was studied in anesthetized and curarized rats, both at various times during (1, 2, 3 and 4 min) respiratory arrest, and after (1, 2, 5, 10 and 60 min) an arrest of 3 min. After 3 min of asphyxia the intracellular lactate concentration had increased to about 22 mMol/kg of i.c. water, while the calculated pHi' had decreased about 0.6 units to 6.50. At the same time almost all phosphocreatine had disappeared, and AMP had increased about tenfold, while there were clearcut, although less drastic, changes in AIP and 4DP. When the asphyxia was prolonged to 4 min the pH reduction apparently inhibited further glucolysis, and asphyxiawasa further fall in pHi'. Upon resumption of ventilation, the ATP, ADP and AMP concentrations, and the calculated cytoplasmatic NADH/NAD+ ratio, normalized within 2 min, and the phosphocreatine concentration as well as the sum of the adenine nucleotides within 5 min, while almost all excess lactate and pyruvate had disappeared within 10 min. There was a gradual and slow normalization of the calculated intracellular pHi' and the tissue was still acid 10 min after restarting the respirator. The three min period of asphyxia was associated with a rapid and marked lactacidosis in arterial blood which was normalized at 60, but not at 10 min. In the CSF, the lactacidosis developed gradually during several min, and the lactate concentration had not normalized until in the 60 min group.
Potentiation of Adrenergic Cardiovascular Effects of Two Quaternary Nicotine Analogues by Reserpine
Authors: Euler U. S. von , Persson N.‐Å.
Published: December 2008

Euler, U. S. V. and N.‐Å. Persson.Potentiation of adrenergic cardiovascular effects of two quaternary nicotine analogues by reserpine. Acta physiol. scand. 1970.78. 459–464.

The quaternary nicotine analoguesiso‐monomethylnicotinium bromide (IMN) and l‐methyl‐3‐(pyrrolidinomethyl)‐pyridinium bromide (MPP) exert only weak effects on the blood pressure and heart rate of the spinalized, vagotomized and adrenalectomized cat in doses of 0.5–1 mg/kg i.v. After a dose of 0.25 mg/kg of reserpine i.v. the effect is strongly potentiated but almost abolished by desipramine. Whereas the pressor effect of nicotine is annulled by hexa‐methonium, the action of the two quaternary compounds is markedly potentiated. The effects of IMN and MPP are also enhanced by previous infusion of prenylamine 0.25 mg/min/kg. It is concluded that reserpine allows IMN and MPP to get access to noradrenaline stores through the axonal membrane and cause a release of neurotransmitter.
Interactions between Inhibitors of the Axonal Amine Pump and Bretylium in the Degeneration Release of Sympathetic Transmitter
Authors: Lundberg Dag
Published: December 2008

Lundberg, D.Interactions between inhibitors of the axonal amine pump and bretylium in the degeneration release of sympathetic transmitter. Acta physiol. scand. 1970.78. 503–521.

The time course of the degeneration contraction of periorbital smooth muscles has been studied in conscious rats given different inhibitors of the axonal mine pump either alone or in combination with bretylium. Desmethylimipramine (DMI) or cocaine at 20 mg/kg did not influence the time of onset of the degeneration contraction while Lu 3–010 (10 mglkg) caused a somewhat premature start. Lu 3–010, DMI or protriptyline at 10 mg/kg but not trimipramine or cocaine at 20 mglkg antagonized bretylium. They reduced and prevented (DMI) the bretylium‐induced delay. DMI reduced the delay by a non‐competitive mechanism. The antagonism to bretylium does not seem to be explainable by simple interference with the axonal amine pump. Indirect evidence suggests that the duration of the delay induced by bretylium is related to the rate of disappearance of bretylium from critical sites in the nerve endings. –DMI and Lu 3–010 seem to have somewhat different actions on the degenerating adrenergic nerve terminals.
Rate Changes in Spontaneous Neuronal Impulse Sequences
Authors: Heino Timo A. , Hyvärinen Juhani , Sovijärvi Ansi R. A.
Published: December 2008

Heino, T. A., J. Hyvarinenand A. R. A. Sovijärvi,Rate changes in spontaneous neuronal impulse sequences. Acta physiol. scand. 1970.78. 529–538.

Sudden rate changes in spontaneous activity were seen in 16 cells of 373 examined under light urethane anesthesia in various diencephalic, striatal, and limbic areas of rabbits. The stochastic properties of the rate varying impulse sequences were examined with statistical techniques. In this material, the dispersion of impulse interval lenghts was a uniform function of the mean discharge rate. For a range of spontaneous activity from 1.5 to 73 imp/sec, this relation was adequately expressed by the equation s=1.42 m1.42, wheremis the mean interval in seconds and s is the standard deviation of the interval lengths in seconds. This relation held for means and standard deviations from different cells as well as for different values from the same cell. In one half of the cells, a time series analysis revealed no change in the stochastic properties of the impulse sequence at the time of the rate change. In other cells, a periodic, rhythmic activity was disclosed during slower discharge rates, but it was not present in the faster activity; or vice versa. In yet other cells, the changes in mean discharge rate were paralleled by similar changes in the frequency of the rhythm. Except for the rhythmic periodicity, all the stochastic properties examined were related to the mean frequency of firing.
The Release of Histamine, Heparin and Granule Protein from Rat Mast Cells Treated with Compound 48/80 in vitro
Authors: Fillion Gilles M. B. , Sloragh Stuart A. , Uvnäs Börje
Published: December 2008

Fillion, G. M. B., S. A. Slorachand B. Uvnäs.The release of histamine, heparin and granule protein from rat mast cells treated with compound 48/80 i n vitro. Acta physiol. scand. 1970.78. 547–560.

The quantitative relationship between the release of histamine, heparin and granule protein from rat mast cells exposed to compound 48/80in vitrohas been investigated in order to clarify the mechanism of action of this releaser. A correlation was found between the three release curves. The ratio of heparin to granule protein was similar in extruded granules and granules remaining in the cell after compound 48/80 treatment. From these results we conclude that the principal mechanism of histamine release induced by this agent involves an initial extrusion of histamine‐containing granules, followed by an exchange of histamine in the granules for cations in the extracellular medium.
Facts and Artifacts in Gradient Gentrifugation Analysis of Catecholamine Granules
Authors: Lagercrantz H. , Pertoft H. , Stjärne L.
Published: December 2008

Lagercrantz, H., H. Pertoftand L. Stjärne.Facts and artifacts in gradient centri‐fugation analysis of catecholamine granules. Acta physiol. scand. 1970.78. 561–566.

Estimates of the “true” density of catecholamine (CA) storage granules from sympathetic nerves and adrenal medulla have previously been largely based on sucrose density gradient centrifugation. In view of the danger of osmotically induced artifacts in this type of combined density and osmolarity gradient the present experiments were carried out to determine the sedimentation characteristics of different classes of CA granules in silica gradients of homogenous and adjustable tonicity. In isotonic gradients chromaffin granules were found to be of about the same density as the majority of nerve granules and mitochondria. When the gradients were deliberately made hypertonic this did not affect the sedimentation characteristics of nerve granules, but caused the chromaffin granules to equilibrate at a considerably higher density level and to separate very distinctly from the mitochondria, indicating a higher degree of osmotically induced shrinking of chromaffin granules, or alternatively a higher permeability to sucrose in these particles.
Cyclic Variation in the Secretion of Seminal Fructose in Rabbits
Authors: Degerman G. , Kihlström J. E.
Published: December 2008

Degerman, G. and J. E. Kihlström. Cyclic variation in the secretion of seminal fructose in rabbits. Acta physiol. scand. 1970. 78. 567–570.

A cyclic variation of the level of seminal fructose in rabbits has been demonstrated by the use of power‐spectrum‐analysis. As the production of this substance is regulated by the testicular hormones, also the activity of these hormones is supposed to vary cyclically.
The Stimulating Effect of Angiotensin and Vasopressin on Adenosine Triphosphatase Activity in vitro
Authors: Levin Klas
Published: December 2008

Levin, K.The stimulating effect of angiotensin and vasopressin on adenosine triphosphatase actiuity in vitro. Acta physiol. scand. 1970.79. 37–49.

The effect of angiotensin on the levels of ATPase activity in homogenates of rat kidney cortex and other tissues has been studied. With the addition of 1.7 μg of angiotensin per ml of incubation medium containing in addition 4 mM ATP, Mg++, Na+, K+, EDTA and imidazole buffer pH 7.2, a stimulation of 8.6 ± 0.5 % of the ATPase activtiy was observed. The presence of Mg++and Na+was found to be necessary for the demonstration of angiotensin stimulation. The optimal pH for the effect of angiotensin was found to be 7.2 and this was confined to very narrow limits. The degree of stimulation was greatest in fresh homogenates and this rapidly decreased on storage. Centrifugation of the homogenates indicated that the ATPase activtiy which could be stimulated by angiotensin was particle bound. A similar effect to the one produced by angiontensin was obtained with vasopressin though not with oxytocin or a number of other vasoactive substances known to effect the renal handling of sodium ions. Stimdation by angiotensin could be demonstrated in kidney cortex from mouse, guinea pig, rabbit, rat and from man, and in homogenates from a number of other tissues. It was concluded that the stimulation of ATPase by angiotensin was brought about through the same mechanisms as the stimulation produced by ouabain, and that both these phenomena are closely related to Na+‐K+ATPase. The possible physiological significance of these findings is discussed.
Osmotic Factors Determining the Release of Catecholamines from Isolated Chromaffin Cell Granules
Authors: Lishajko F.
Published: December 2008

Lishajko, F.Osmotic factors determining the releme of catecholamines from isolated chromaffin cell granules. Acta physiol. scand. 1970.79. 64–75.

On incubation of bovine adrenal medullary granules in isotonic sucrose, KCl, NaCl or K‐phosphate, noradrenaline (NA) is initially released at a rapid rate followed by a slow exponential release. Adrenaline (A) release in the same media does not show the rapid initial phase. In hypotonic media both NA and A show a rapid initial release while in hyper‐tonic solutions both NA and A are released at a constant slow rate (t/2 = 115–185 min at 37°). Partial replacement of sucrose or dextrose media by NaCI, KCl or K‐phosphate decreases the release rate of Na and A. Addition of 6 mM Mg2+or Ca2+prevents the initial rapid fall of NA and of A in hypotonic solution. ATP‐Mg2+inhibits the release rate of catecholamines in chloride free media more than ATP or Mg2+alone. The granules were shown to shrink in the presence of divalent ions, as well as on addition of ATP or ATP‐Mg2+. During partial lysis or “osmotic shock” the granules lose slightly more A than NA. The results suggest that the NA containing granules from chromaffin cells initially possess a higher osmotic pressure than that of the A granules, possibly depending on the rate of splitting of an amine‐ATP‐complex. The release may depend partly on the ensuing osmotic equilibration process.
Salivary Glands of the Rat in a Hot Environment
Authors: Elmér Mats , Ohlin Per
Published: December 2008

Elmér, M. and P. Ohlin. Salivary glands of the rat in a hot environment. Acta physiol. scand. 1970. 79. 129–132.

A marked hypertrophy of the normally innervated submaxillary gland was observed in rats subjected to heat (34°C) for 3 weeks. The increase in weight of parasympathetically de‐xiervated glands was much less while that of sympathetically denervated glands was still pronounced. The size of both synipathetically and parasympathetically denervated glands was not affected in a hot environment. It seems likely that the hypertrophy of the submaxillary gland is to a large extent secondary to an increased secretory activity elicited by the para‐sympathetic secretory fibres. A corresponding increase in weight of the sublingual gland was not seen.
The Influence of an Increased Intracranial Pressure on the Lactate, Pyruvate, Bicarbonate, Phosphocreatine, ATP, ADP and AMP Concentrations of the Cerebral Cortex of Dogs
Authors: Zwetnow Nicolaus N.
Published: December 2008

In order to study effects of increased cerebrospinal fluid pressure upon brain tissue concentrations of bicarbonate, lactate, pyruvate, ATP, ADP, AMP and phosphocreatine, the metabolites were measured in cortical tissue of 37 dogs frozen in situ during and after a 15 min decrease of the cerebral perfusion pressure to 30–35 mm Hg, induced by connecting the cisterna magna to a reservoir with artificial CSF. The intracranial hypertension was found to give a variable but marked increase in tissue lactate and pyruvate, and in the lactate/pyruvate ratio, as well as a corresponding decrease in the bicarbonate concentration. Marked decreases in the ATP and phosphocreatine concentrations were also seen. Resting values for these metabolites were not approached until 30–90 min after restitution of normal perfusion pressure. Since the changes in ATP and phosphocreatine corresponded in time to the changes in the lactate, pyruvate and bicarbonate concentrations it is concluded that the decrease in the cerebral perfusion pressure gave rise to a longlasting disturbance of the oxidative metabolism, possible due to reversible structural tissue damage. Cerebral blood flow measured in 10 of the dogs showed varying decreases of cerebral blood flow during the intracranial hypertension period. Usually, hyperemia of 30–90 min duration followed when the CSF pressure was released. The hyperemia and the metabolic changes were of approximately the same duration.
The Rising Phase of the Active State in Single Skeletal Muscle Fibres of the Frog
Authors: Edman K. A. P.
Published: December 2008

An approach of analyzing the initial phase of the active state in single skeletal muscle fibres of the frog has been designed. The fibre was stimulated to generate a series of four incompletely fused isometric twitches with the object of producing distinct peaks and throughs in the myo‐gram. The peaks and troughs of the records both represent the tension output when the contractile unit was stationary. The tension recorded at these instances therefore provided an adequate measure of the intensity of the active state at respective times after the stimulus. By releasing the fibre at different moments during the third cycle it was possible to define 1. the decay phase of the active state in the third cycle and 2. a substantial portion of the rising phase of the active state in the fourth cycle. It was found that the active state underwent a very rapid increase starting at 12 msec after the stimulus (at 1–2° C). Only 3–4 msec were required for the active state to rise from 25 to 65 per cent of its peak value. The rate of rise of the active state was independent of the sarcomere length (between 2.8 μ and 2.0 μ) and of the degree of activity existing in the fibre when the fourth stimulus was applied. The implications of the results with respect to the kinetics of the calcium‐activator mechanism in the excitation‐contraction coupling are discussed.
Studies on Kinin Formation in Functional Vasodilatation of the Submandibular Salivary Gland in Cats
Authors: Gautvik Kaare
Published: December 2008

The submandibular salivary gland in cats has been perfused undcr conditions of constant volume inflow with red blood cells suspended in normal cat plasma. Such a method is favourable for studying the time course of changes in glandular vascular resistance. A 30 sec supra‐maximal stimulation of the chordo‐lingual nerve caused the vascular resistance to fall markedly within 1–6 sec. When the nerve stimulation was finished, a further decrease in perfusion pressure was usually observcd, whereafter a slow increase in vascular resistance took place.

The rapidity with which the vascular response occurred indicates an initial direct action of true vasodilator nerve fibres.

The second phase of the vasodilatation, outlasting the chorda stimulation itself, is claimed to be mediated by kinin formation in the activated gland:

a) When the gland was perfused with normal cat plasma, so that resting perfusion pressure was low (under 55 mm Hg), then the vasodilator response to chorda stimulation changed, developing gradually and outlasting the nerve stimulation.

b) Reduction of kininogen 2 in the plasma perfusate resulted then in a reduced vasodilator response to chorda stimulation.

c) With no kininogen 2 in the cell‐free perfusate, stimulation of the chordo‐lingual nerve caused only a very small vasodilatation or no vasodilatation at all.

d) Addition of partly purified kininogen 2 to such perfusate did then restore the chorda‐induced vasodilatation.
The Interaction of Two Different Vasodilator Mechanisms in the Chorda‐Tympani Activated Submandibular Salivary Gland
Authors: Gautvik Kaare
Published: December 2008

The vasodilatation caused by stimulation of the chordo‐lingual nerve has been studied in the cat submandibular salivary gland perfused under conditions of constant volume inflow, at a rate equal to the flow existing in the resting organ.

When a perfusate of red cells suspended in normal plasma was used at perfusion pressures of 55–120 mm Hg, a typical two‐phasic and long‐lasting vasodilatation was observed as a response to nerve stimulation. This vasodilator pattern was maintained when repeated nerve stimulations were carried out during a single perfusion period. Wlien the gland was perfused continuously with red cells suspended in a kininogen‐free solution then one of two different response patterns could be seen, When a low perfusion pressure prevailed (below 55 mm Hg), then the chorda‐mediated vasodilatation was reduced or abolished on repeated nerve stimulation. At conditions with a higher perfusion pressure (60–120 mm Hg) there developed on chorda stimulation a one‐phasic, short‐lasting vasodilatation, which was not reduced on repeated stimulations.

In another series of experiments the kinin‐destroying activity of a perfusate of red cells in normal plasma was increased by addition of carboxypeptidase‐B. Chorda stimulation then caused a short‐lasting vasodilatation of the type seen when a red cell perfusate containing no kininogen was used.

It is concluded from these findings that functional vasodilatation in the submandibular salivary gland is probably initiated by the effect of vasodilator nerve fibres and supported and maintained by the action of kinins formed in the activated gland.
Effect of Age on the Collagen Content of the Normal Rat Myocardium
Authors: von Knorring Johan
Published: December 2008

The development of the collagenous tissue in the myocardium was studied in rats aged one day to 18 months. During the first three weeks a rapid exponential increase of both the heart weight and the total amount of myocardial hydroxyproline occurred, although the concentration of total and insoluble hydroxyproline as estimated per mg of dry tissue showed no significant change. Thereafter the growth rates of the heart weight and total and insoluble hydroxyproline fell with increasing age. The growth rate of total hydroxyproline fell more slowly, however, and a slight increase in the content of total and insoluble hydroxyproline per dry tissue was noted with increasing age. The proportion of neutral salt‐soluble collagen hydroxyproline in the myocardium dropped from an initial value of 30 per cent of the total hydroxyproline in newborn rats to 10 per cent at the age of three weeks. After this the proportion of soluble hydroxyproline remained almost unchanged. At the same time the proportion of free hydroxyproline dropped from 25 per cent of the total hydroxyproline in newborn rats to 1.3 per cent at the age of 6 months. The results seem to suggest that during the postnatal period insoluble mature collagen develops rapidly, and therefore with increasing age constitutes a slowly rising proportion of the myocardial collagenous framework. This seems to be a response to the functional demand on the growing heart for increased tensile strength.
The Effect of Amiloride on Sodium Transport in the Normal and Moulting Frog Skin
Authors: Nielsen Robert , Tomilson R. W. S.
Published: December 2008

It is shown that amiloride is a potent inhibitor for the active sodium transport across tht‐isolated frog skin. The percentage inhibition produced by various amiloride concentrations was not dependent on the initial short‐circuit current but rather on the phase of the moulting cycle at which the skin was tested.
Metabolic Actions in Intestinal Smooth Muscle Associated with Relaxation Mediated by Adrenergic α‐ and β‐Receptors
Authors: Andersson Rolf , Mohme‐Lundholm Ella
Published: December 2008

In colonic muscle from the rabbit a relaxing effect was induced by stimulation both of adrenergic α‐receptors with phenylephrine and of β‐receptors with isoprenaline. The α‐receptor induced relaxation was not accompanied initially by any metabolic effects. After a latency period of 3 min did a decrease in the phosphorylase α activity, a decrease in the concentrations of hexose phosphates and lactate and an increase in the concentration of high‐energy phosphate compounds (ATP and CrP) become evident. There was a decrease of the cyclic AMP content. These effects were inhibited by dibenamine. The relaxation induced via adrenergic β‐receptors was preceded by an increase in the cyclic AMP content and the phosphorylase α activity, an increase in the concentration of hexose phosphates and lactate and an initial decrease of the ATP and CrP concentrations, which after 10 min was succeeded by an increase. The magnitudes of the relaxing and metabolic responses following stimulation of preceptors were correlated with regard to time and dose. These responses were blocked by an adrenergic β‐receptor blocking agent (sotalol) and were also eliminated in carbohydrate‐poor muscle. The relaxing and metabolic effects of isoprenaline could be reproduced completely by cyclic AMP, only incompletely by 5'AMP and not at all by other tested cyclic nucleotides.
Effects of Varied Cerebrospinal Fluid Pressure on Cerebral Blood Flow in Dogs
Authors: Häggendal Egil , Löfgren Jan , Nilsson Nils Johan , Zwetnow Nicolaus N.
Published: December 2008

Effects of short‐term variations in cerebrospinal fluid pressure on cerebral blood flow in dogs were measured with the radioactive krypton clearance technique of Lassen et al. The cerebrospinal fluid pressure was increased stepwise by infusion of artificial cerohrospinal fluid, the pressure range from ‐15 to +150 mm Hg being investigated. The cerebral blood flow remained virtually stable, when the induced cerebrospinal pressure was lower than about 100 mm Hg. At higher values the cerebral blood flow began to fall. Thus, the existence of flow auto‐regulation was demonstrated also for the situation when perfusion pressure is reduced by a rise of the intracranial pressure. At very high cerebrospinal fluid pressures an additional reaction appeared in the form of a rise in the systemic arterial blood pressure. A discussion of the relative roles of these two regulating mechanisms is given.
Prolonged Cerebral Hyperemia after Periods of Increased Cerebrospinal Fluid Pressure in Dogs
Authors: Häggendal Egil , Löfgren Jan , Nilsson Nils Johan , Zwetnow Nicolaus N.
Published: December 2008

In 23 dogs the cerebral blood flow was measured with the intra‐arterial radioactive injection technique during and after the application of a high cerebrospinal fluid pressure by infusion of artificial cerebrospinal fluid into the subarachnoid space. Increased cerebral blood flow was observed in most cases when the cerebral perfusion pressure was restored after a period with cerebrospinal fluid pressure over 50 mm Hg. The hyperemia always occurred if during the period of high intracranial pressure the blood flow had been reduced below the control value: in a few cases it appeared also without a preceding flow reduction. In almost all cases there was a marked tendency to normalization of the blood flow after the initial period of hyperemia. No chemical factors in the artificial cerebrospinal fluid could be made responsible for the phenomenon described, which is attributed to a disturbance of cerebrovascular function, impairing the ordinary flow autoregulation.
Some Characteristics of Lipolysis in Rabbit Adipose Tissue. Effects of Noradrenaline, ACTH, Theophylline and Prostaglandin El
Authors: Micheli Horace
Published: December 2008

Perirenal adipose tissue from rabbits of different strains was incubated in vitro and the glycerol release determined to evaluate the lipolysis. Noradrenaline was found to stimulate lipolysis, but to a lower degree than ACTH. From one strain of rabbits it was apparent that lighter (younger) rabbits were more responsive to noradrenaline than heavier (older) animals, some of which were completely unresponsive to the catecholamine. Theophylline as well as PGE, were ineffective when added alone to the incubation medium. However, theophylline increased the glycerol release induced by noradrenaline and low concentrations of ACTH and PCE, inhibited lipolysis under these conditions. The results suggest that there is a low rate of formation of cyclic AMP in rabbit adipose tissue under basal conditions of incubation while the hormonal stimulations might well operate by means of increasing the accumulation of cyclic AMP.
Vasoactivity of Adenine Nucleotides Released in vitro from Blood Cells by Thrombin
Authors: Swedenborg Jesper
Published: December 2008

Small amounts of thrombin infused into the Cenioral artery of dogs decrease the peripheral vascular resistance, due to release of adenine nucleotides from blood cells.

The present study was designed to determine the source of vasoactive adenine nucleotides released from blood cells by thrombin. Washed human platelcts, red cells and white cells were incubated with thrombin and the resulting supernatant was tested for vasoactivity. Dog platelet rich plasma and platelet poor plasma incubated with thrombin was also assayed for vasoactivity, as well as hemolysed red cells. Supernatants from incubated platelets showed strong vasocativity which disappeared after exposure to ADP‐ase and ATP‐ase (Apyrase). Supernatants from red cells and white cells were not vasoactive. Platelet rich plasma incubated with thrombin was highly vasoactive in contrast to platelet poor plasma treated similarly. Hemolysed red cells were highly vasoactive and this vasoactivity also disappeared after treatment with Apyrase. It is concluded that small amounts of thrombin release adenine nucleotides from the platelets. This does not occur when red cells or white cells are acted upon by thrombin although the major supply of the nucleotides is to be found in the red cells.
Myoneural Ultrastructure and Cholinesterases after Tetrodotoxin Treatment
Authors: Teräväinen H.
Published: December 2008

Intraperitoneally injected tetrodotoxin, irrespective of the dose given, caused no changes in the ultrastructure of the myoneural junctions of the rat striated muscle, or in their histo‐chemically demonstrable acetyl (E.C. 3.1.1.7.) or non‐specific (E.C. 3.1.1.8.) cholinesterase activity.
Characterization of Ovarian RNA
Authors: Ahrén Kurt , Hamberger Lars , Jarlstedt Jan , Nilsson Lars
Published: December 2008

Ovaries were obtained from 24–25 day old Sprague‐Dawley rats. Groups of 20 ovaries were collected corresponding to a wet weight of 100–120 mg, and incubated for 20, 30, 60 and 240 min at 37° C in Krebs bicarbonate buffer containing 5.5 mM glucose and uridine‐3H. Following incubation, ovarian RNA was extracted with a modified phenol extraction method described in detail. Fractionation was made by composite agarose‐polyacrylamide gel electrophoresis which gave good separation and high resolution of the various RN.4 fractions. Ovarian RNA separated in four well‐defined fractions classified as 28S, 18S, 5s and 4s. This classification was based upon comparisons with simultaneously run liver RNA. In addition to the four main fractions. a weak band just before 28S and two smaller bands between 28S and 18S were consistently observed. Labelling of ovarian RNA with uridine‐3H showed a polydisperse pattern after the shorter incubation periods with most of the radioactivity concentrated to RNA fractions of molecular weights higher than 28S, but also clear labelling of the 5S—4S region. After 60 min, radioactivity peaks were also associated with the 28S and 18s fractions and with fractions between those, while after 240 min incubation, the radioactivity was concentrated to the four main fractions. The incorporation of radioactivity was found to be markedly decreased in presence of actinomycin D.
Dopamine Secretion from the Isolated Perfused Sheep Adrenal
Authors: Lishajko F.
Published: December 2008

Isolated sheep adrenals, perfused with Tyrode solution, release in addition to adrenaline (A) and noradrenaline (NA) small amounts of dopamine (DA) into the effluent. The amines appeared in the perfusate even in the absence of C1 or Ca2+ions. Addition of ACh to the per‐fusion fluid increased NA and A in the effluent 2–3 times and DA about 5 times. In calcium and chloride free Tyrode solution carbachol increased secretion 1.7–2.7 times for all 3 amines. Reintroduction of Ca2+into the media increased the response to ACh and carbachol 5–7 times. Injection of Ca2+into the perfusion fluid further increased the secretory response to simultaneously added. ACh and carbachol 14–18 times for all 3 amines.
Steps in Impulse Generation in the Isolated Muscle Spindle
Authors: Ottoson D. , Shepherd G. M.
Published: December 2008

The interrelationship between the different steps in the generation of the afferent discharge was studied in isolated frog spindles. Attention was focused on the prepotential and its relation to the receptor potential and to the frequency of the impulse divcharge during various phases of controlled stretches. It was found that the rate of rise of the prepotential increased linearly with increasing amplitude of the underlying receptor potential. For stretches of a given strength the rate of rise increased with the velocity of the stretch. The frequency of the discharge was directly related to the rate of rise of the prepotential. A similar relationship was found for the discharge frequency and the amplitude of the receptor potential. The results thus show that there is a close interrelationship between the three main stages of impulse generation. This finding explains the ability of the spindle to pass on faithfully, in the frequency Characteristics of the impulse discharge, information about the properties of the applied stretch.
Chylomicron Size and its Relation to the Composition of Dietary Fat in the Rat
Authors: Sylvén Christer
Published: December 2008

Thoracic duct cannulated rats were fed 50 μmoles of radioactive cholesterol dissolved in medium chain triglyceride (MCT), hydrogenated coconut oil (HCOCO) or triolein. Lymph was sampled and fractionated with ultracentrifugation and gel chromatography. The amount of lymph lipoproteins was estimated by their lipid content. Gel chromatography showed that there was a continuous distribution of lymph lipoproteins according to molecular size. The transport of chylomicron lipoproteins i.e. those of Sf>400 increased with fatty arid chain length of the triglyceride used. When MCT or HCOCO were administered the transport of lipoproteins 400>Sf>20 increased. Administration of triolein gave the same transport as HCOCO. While the transport of both lipoprotein classes was lowest when MCT was used. this triglyceride induced the highest transport of cholesterol in lipoproteins 400>Sf>20. This was reflected in the percentage composition of the lipoprotein lipid. It contained more cholesterol and less triglyceride as compared to the other dietary conditions. Exogenous cholesterol was transported in both lipoprotein fractions.
Transport of Glucose, Sodium, Chloride and Potassium between the Cerebral Ventricles and Surrounding Tissues in Cats
Authors: Brondsted H. E.
Published: December 2008

The ventriculo‐aqueductal perfusion technique was used in order to study the mechanism for transport of glucose, sodium, chloride and potassium between the cerebral ventricles and surrounding tissues in cats. The inflow perfusion fluid contained U14C‐D‐glucose and un‐labelled D‐glucose. With D‐mannose or D‐xylose in the inflow, the unidirectional flux of glucose from the cerebral ventricles was inhibited competitively. Ouabain in the inflow (10‐7M or 10–45M) and potassium‐free inflow reduced the rate of cerebrospinal fluid formation while the tissues lost potassium and gained sodium and chloride. The presence of ouabain reduced the unidirectional flux of glucose from the cerebral ventricles. The effects increased using higher concentrations of ouabain (up to 5 times 10‐5M). Injections of increasing amounts of ouabain into the internal carotid artery had 110 effects upon the above mentioned variables. The results support the idea that ouabain‐sensitive carrier‐mediated transport of glucose from the cerebral ventricles may be connected with the mechanism for active transport of ions.