bluuebunny/crossref_metadata_2025 huggingface dataset:
Transfer of TRH through the Placenta and Metabolism in the Fetus of the Guinea‐Pig
Authors: Lybeck Harry , Virkkunen Pekka
Published: December 2008

The permeability of the placenta to thyrotropin‐releasing hormone (TRH) and the fetal metabolism of this hormone were studied by giving iodine‐labelled synthetic TRH to pregnant guinea‐pigs during the first trimester. The radioactivities of various tissue fluids (serum, urine, amniotic fluid and maternal bile) and tissue samples (kidney, liver, small intestine, muscle and cortex) of both mother and fetus were counted. The biological activity of the transferred synthetic TRH was measured in fetal serum by bioassay. Direct measurements of placental permeability to TRH is presented. In the mother the metabolism seems to be the same as in mice and rats (Redding and Schally 1971, Virkkunen, Leppaluoto and Lybeck 1972). In the fetus the main elimination route of TRH is through the liver to bile, in contrast to the rapid urinary excretion in the mother. The half‐life of TRH in the fetal serum is about ten times as long as in the mother, reflecting a different elimination mechanism. Fetal tissue concentrations of TRH are comparable to those of the mother, and so may trigger the endocrine development of the fetal thyroid‐adenohypophyseal system.
The Variation with Age of Tissue Zinc Concentrations in Albino Rats Determined by Atomic Absorption Spectrophotometry
Authors: Bergman Bo , Sjoström Rolf , Wing Kenneth R.
Published: December 2008

An atomic absorption spectrophotometry method for the determination of zinc concentrations in biological tissue samples has been refined. All samples are ashed for 16 hours at 550° C and each determination on a mineralized tissue sample is corrected for the absorption due to the high calcium concentration by subtracting a further absorption measurement at a second wavelength. The method is without detectable systematic error, except for 15–20 % losses of zinc from serum samples, and the random error is less than 2 %. The method was compared with neutron activation analysis on duplicate tissue ash samples and the agreement of the determinations was very good. The method was used to determine the zinc concentrations in samples of serum, heart and selected viscera, teeth and bones from albino rats at various ages during growth. Of these, only the zinc concentration in heart is stable. In pancreas and incisor crowns the concentrations are correlated to the serum concentration and those in the bone samples are correlated to the total mineral (ash) content in each. The ash weight zinc concentrations in bones, the fresh weight concentrations normalized to the total mineral content, are correlated to the serum zinc concentrations.
Relationship between Perivesical and Intravesical Urinary Bladder Pressures and Intragastric Pressure
Authors: Bjerle Per
Published: December 2008

The intragastric pressure and the perivesical and intravesical urinary bladder pressures were measured in the supine and sitting positions immediately after micturition in 9 healthy men. The intragastric pressure was measured with an air‐filled rubber balloon, the perivesical pressure with an open liquid‐filled catheter inserted above the pubic bone into the space of Rezius and the intravesical pressure of the almost empty bladder with a catheter inserted supra‐pubically. There was no difference between the intragastric pressure level and the peri‐ and intravesical pressure levels in the supine position, but in the sitting position the peri‐ and intravesical pressure levels were higher than the intragastric pressure levels due to the pressure effect of the viscera. There was no difference between perivesical and intravesical pressure levels in either the supine or sitting position. Rapid pressure change produced by straining or coughing produced a smaller pressure increase peri‐ and intravesically than intragastrically due to delayed pressure equilibration because of inhomogeneity of the abdominal contents.
The Hypothalamus and Vagally Mediated Gastric Relaxation
Authors: Lisander Bjorn
Published: December 2008

Experiments, with recording of gastric volume, were performed in chloralosed cats. Topical hypothalamic stimulations produced vagally mediated increases in volume by two mechanisms. One type of response, due to central inhibition of vagal excitatory tone was induced from the defence area and eliminated by atropine or vagotomy. The other type of response, far less commonly encountered, remained after atropine and spinal cord section, but was abolished by vagotomy. The latter type was not induced from any well defined hypothalamic region, and had a high stimulation threshold. While sham feeding in conscious cats with esophagostomy and gastrostomy induced prompt, marked and longlasting gastric volume increases in connection with swallowing, such responses were not evoked as “anticipatory” reaction to food intake. The relaxations could be prevented by vagotomy but not by guanethidine nor atropine. It is concluded that the vagally mediated relaxation in connection with sham feeding occurs mainly from activation of mechanoreceptors and that the hypothalamic control over the vagal relaxatory fibres is probably minor.
Disappearance of 3H‐Corticosterone from the Serum of Obese‐Hyperglycemic Mice (Gene Symbol ob)
Authors: Naeser Peter
Published: December 2008

The disappearance of 3H‐corticosterone from the serum was measured in obese‐hyperglycemic mice and their lean litter mates of various ages. At 1 month of age the serum half‐life of the injected tracer was the same in the obese and lean animals. In the 2, 5 and 12 months old mice the tracer hormone disippeared faster in the obese mice than in their lean controls. The present results confirm that the previously observed enlargement of the adrenal cortex and the increased secretion of corticosteroids by adrenal glands in vitro in fact indicate a considerably hyperadrenocorticism in the obese mouse. Furthermore, the difference in disappearance rate of corticosteroids in vivo between obese and lean mice approximately parallels the age variation of the other metabolic abnormalities of the syndrome suggesting that the hyperadrenocorticism is part of the multiendocrine disturbance which manifests itself as the obese‐hyperglycemic syndrome.
Prostaglandin Release and Mechanical Performance in the Isolated Rabbit Heart during Induced Changes in the Internal Environment
Authors: Wennmalm Ake
Published: December 2008

The isolated rabbit heart was perfused according to the Langendorff technique. Prostaglandins in the effluent from the organ were identified by use of thin layer chromatography and assayed on the rat stomach strip, The effect of alterations of the physical and chemical conditions of the perfusion medium on the overflow of prostaglandins from the heart was studied. In addition, the capacity of noradrenaline and acetylcholine to release prostaglandins was tested. Acidosis, hyperthermia. hypothermia, hypotension, hyperosmolarity and increased [K+] or [Ca++] levels, while all inducing marked changes in the mechanical activity of the heart, did not induce prostaglandin release. Hypoxia, on the other hand, stimulated the liberation of prostaglandins. Noradrenaline was a potent agent for stimulation of prostaglandin release, in the absence of alpha‐ and betaadrenergic receptor blockade. Acetylcholine was also found to liberate prostaglandins, by activation of muscarinic receptors. The prostaglandin releasing capacity of acetylcholine was about 3 times weaker than that of noradrenaline. It is concluded that the release of prostaglandins from the rabbit heart is not dependent on the mechanical activity of the organ. Furthermore, it is suggested that prostaglandins released by hypoxia may play an important role in the development of reactive hyperemia. Finally it is stated that the release of prostaglandins from the heart caused by acetylcholine may constitute the negative link in an endogenous prostaglandin mediated feed‐back inhibition of the release of acetylcholine from parasympathetic nerve endings.
Role of the Symphato‐Adrenal System in Hemorrhagic Hyperglycemia
Authors: Järhult Johannes
Published: December 2008

Arterial and venous plasma glucose concentration was determined at intervals in cats subjected to hemorrhagic hypotension at 50 mm Hg. The rapid rise of arterial plasma glucose after hemorrhage could be. attributed to an increased release of glucose from the liver. This hyperglycemia could not be eliminated by bilateral adrenalectomy or by sectioning of the hepatic sympathetic nerves, although the response was somewhat depressed by the latter procedure. On the other hand the hyperglycemia was virtually abolished after adrenalectomy when combined with bilateral sectioning of the major and minor splanchnic nerves. The level of plasma glucagon during hemorrhage increased in cats with an intact sympatho‐adrenal system, but was unchanged in animals with combined splanchnic sympathectomy and adrenalectomy. It is concluded that, during hemorrhage, the sympatho‐adrenal system influences the glucose output from the liver by three different reflex mechanisms: (a) release of catecholamines from the adrenal glands; (b) direct sympathetic nerve influence on the liver; and (c) release of glucagon from the pancreas.
Some Metabolic Consequences of the Anaphylactic Reaction in the Rabbit
Authors: Fredholm Bertil B. , Strandberg Kjell
Published: December 2008

The administration of egg albumin to rabbits sensitized to this antigen caused marked increases in the arterial concentration of lactate, glucose and glycerol, but no change in the arterial FFA level. Antigen administration had no effect in non‐sensitized rabbits. Phentolamine (3 mg/kg) or propranolol (1 mg/kg) did not significantly alter the responses to egg albumin in sensitized rabbits. Noradrenaline or sympathetic nerve stimulation decreased blood flow but caused no significant change in lipolysis in rabbit epigastric adipose tissuein situ. It is therefore questionable if catecholamines are the major cause of the observed metabolic consequences of the anaphylactic reaction in the rabbit. These metabolic events,i.e. increased lactate levels, lipolysis, and reesterification of fatty acids, are similar to those reported during hemorrhagic or endotoxin shock in dogs, in spite of species‐differences and the difference in the genesis of the shock.
Effect of Substance P on Various Vascular Beds in the Dog
Authors: Hallberg Dag , Pernow Bengt
Published: December 2008

Using the electromagnetic flowmeter technique, the blood flow in the aorta, carotid, hepatic, superior mesenteric, renal and femoral arteries and portal vein was recorded during continuous i.v. infusion of synthetic Substance P (SP) in 8 dogs. Systemic and portal blood pressures were recorded. A significant decrease in mean arterial blood pressure was recorded at infusion of SP in the femoral vein at a rate of 2.5 ng × min‐1× kg b.w.‐1 or higher. Portal venous blood pressure increased. A rapid increase in the carotid, hepatic, mesenteric and portal blood flow was obtained at infusion rates of 1.2 ng × min‐1× kg b.w.‐1 or higher. The femoral artery responded with a late, transient increase in flow, with a return to the base level while the infusion was still in progress. The renal artery blood flow decreased slightly at low infusion rates and increased at higher. At SP infusions in the portal vein the infusion rate had to be increased to 20 ng × min‐1× kg b.w.‐1 or higher before any general vascular reactions were recorded, indicating that the liver has a high capacity for inactivating SP.
Mitochondrial Respiration in the Ventricular Myocardium and in the White and Deep Red Myotomal Muscles of Juvenile Tuna Fish (Thunnus thynnus L.)
Authors: Modigh M. , Tota B.
Published: December 2008

The respiratory activity of mitochondria isolated from the outer and inner layers of the ventricular myocardium and from the white and deep red myotornal muscles of juvenile Thunnus thynnus has been compared. The highest values for the succinate oxidase and succinate cytochrome c reductase activities have been found in the mitochondria of the outer myocardial layer, followed by mitochondria of the deep red muscle, the inner myocardial layer and the white muscle in that order. Differences in mitochondrial NADH‐cytochrome c reductase activity run parallel, in a lower order of magnitude, to the differences in the oxidation of succinate. This finding is discussed in relation to the different metabolic attitudes of the muscle tissues towards anaerobic glycolysis. The outer myocardial layer of the juvenile tuna ventricle has been shown to have a higher metabolic activity than the inner layer, in contrast to the situation in adult ventricular myocardium.
Detection of Natural Complex Sounds by Cells in the Primary Auditory Cortex of the Cat
Authors: Sovijärvi Anssi R. A.
Published: December 2008

The neural mechanisms involved in the detection of natural complex sounds were studied by recording single‐neuron responses from 132 cells in the primary auditory cortex of the cat. The cats were paralyzed and under neuroleptanalgesia (NLA). The cells were first stimulated with pure tones; the responses were then compared with those evoked by many different types of complex sounds, most of which were animal vocalizations. Per‐stimulus‐time (PST) histograms constructed from the responses to repetitive stimuli were compared with the corresponding sound spectrograms formed from the sounds used as stimuli. Of 100 cells 68 per cent gave predictable responses to complex sounds on the basis of their responses to different pure tone frequencies. In 32 per cent of the cells the responses were unpredictable. Half of these cells did not react to pure tones at all but responded to one or more animal vocalizations or generator sounds with different patterns. Some cells reacted to pure tones in quite a different way than to certain complex sounds, e.g. with inhibition instead of excitation. These results indicate that cells in the primary auditory cortex of the cat reacting in an unpredictable way to sounds with a complex structure have a more or less specialized function, in detecting and analyzing natural and other complex sound patterns. Cells reacting phasically to pure tones seem to be involved in the detection of transient sound elements.
Clearance of Some Quaternary Amines from the Spinal Subarachnoid Space*
Authors: Aquilonius S.‐M. , Winbladh B. , Zillén S.
Published: December 2008

The spinal subarachnoid space was perfused with artificial cerebrospinal fluid (CSF) from the low lumbar level to the middle thoracic level or to the cisterna magna in anesthetized rabbits. 3H‐choline, 3H‐methyl‐atropine or 3H‐decamethonium with carrier in different concentrations was added to the perfusate together with 14C‐inulin, the latter serving as a marker of the dilution of the perfusate by original CSF. Choline was eliminated from the perfusate partly by a saturable mechanism probably by an uptake into the spinal cord. About 15 per cent of the radioactivity of the choline infused was recovered from the spinal cord mainly as phosphorylcholine, betaine, and phospholipids. Amphetamine decreased the elimination of choline from ventriculocisternal perfusates and partly inhibited the uptake of choline in rabhit choroid plexus in vitro. In contrast, amphetamine did not influence the saturable elimination of choline in the lumbothoracic perfusion. Neither methylatropine nor decamethonium was eliminated from the perfusate by a saturable mechanism in the lumbothoracic perfusions. However, in perfusions including the cisterna magna methylatropine was partly eliminated by such a mechanism. The concentration of radioactivity in fourth ventricular choroid plexa suggested this structure to be responsible for the saturable part of the elimination. In conclusion, there is no active removal of quaternary amines in general from spinal CSF like the choroid plexus mediated clearance from ventricular CSF.
Brain Carbonic Acid Acidosis after Acetazolamide
Authors: Heuser Dieter , Astrup Jens , Lassen Niels A. , Betz Eberhard
Published: December 2008

In cats in barbiturate anesthesia extracellular pH and potassium were continuously recorded from brain cortex by implanted microelectrodes. Implantation of the electrodes preserved the low permeability of the blood‐brain‐barrier to HCO3and H+ions as indicated by the development of brainacidosisby i.v. injection of HCO3. Acetazolamide (25 mg/kg) i.v. was followed by a marked brain acidosis which after 10 min had progressed to a drop in pH of 0.203 ± 0.046 (x ± S.D., n = 8). The slowness of the development of acidosis points to a direct effect of the carbonic anhydrase inhibition on the brain tissue. As a further support for this conclusion was considered the finding of a prolonged responsetime of brain pH to HCO3i.v., to CO2inhalation, and to hyperventilation after the acetazolamide inhibition. No changes in brain extracellular potassium were found.
The Metabolism of Acetate in the Perfused Hind‐Quarter of the Rat
Authors: Karlsson N. , Fellenius E. , Kiessling K.‐H.
Published: December 2008

The elimination kinetics of acetate, the main end product of ethanol metabolism in the liver and the influence of acetate oxidation on the redox‐ and energy state of the isolated perfused hind‐quarter of the rat were studied. The rate of acetate uptake increased with increasing initial concentration of acetate in the perfusion medium, suggesting that the plasma level of free acetate may be one factor in the regulation of acetate uptake in the skeletal muscle. Addition of acetate as a single dose did not affect the net production of lactate or the uptake of glucose. In continuous infusion experiments at a constant concentration of 2 mM of acetate in the medium, the lactate/pyruvate ratio was unaffected in the medium and in the muscle tissue. Addition of acetate did not affect the oxygen uptake. Experiments with 14C‐acetate showed that about 50% of added radioactivity was found in form of 14CO2, accounting for 25 to 45% of the oxidative metabolism in the muscle tissue. It was calculated that about 25% of the acetate produced in the liver during ethanol oxidation can be consumed in the resting, perfused hind‐quarter of the rat. The tissue content of high‐energy phosphate compounds was not significantly affected by acetate
Incorporation of Leucine into Human Skeletal Muscle Proteins: A Study of Tissue Amino Acid Pools and their Role in Protein Biosynthesis
Authors: Lundholm K. , Scherstén T.
Published: December 2008

The in vitro incorporation of labelled leucine into human skeletal muscle proteins was studied with the aim to elucidate the relationship between the amino acid tissue pools and protein biosynthesis. The distribution volumes of leucine and cycloleucine in skeletal muscle tissue were similar but the equilibration time was shorter for leucine than for cycloleucine. The cellular uptake of leucine and cycloleucine was competitively inhibited by increased concentration of amino acids in the medium indicating an active transport. Optimal stimulation for incorporation of leucine into proteins was obtained at an amino acid concentration in the medium corresponding to 10 times that of normal human plasma. The incorporation of 14C‐leucine into skeletal muscle proteins was linear before the total pool of free intracellular 14C‐leucin had reached an equilibrium. The regression coefficients for the semilogarithmic plots of the labelling rate of proteins with 14C‐leucine and the incorporation rate of leucine calculated from the specific activity in the medium versus the amino acid concentration in the medium were different in the same experiment indicating a re‐utilization of amino acids released at protein degradation. The results are compatible with the hypothesis that the proteolytically released amino acids have a competitive advantage for incorporation as compared with extra‐ and intracellular free amino acids. It is concluded that the amino acid pool which is in the immediate continuity with the protein biosynthesis sites equilibrates rapidly with the extracellular amino acid pool.
Dynamic Properties of Excitation and Inhibition in the Cochlear Nucleus
Authors: Møller Aage R.
Published: December 2008

The dynamic properties of inhibition and excitation of single units in the cochlear nucleus were studied using tones that were amplitude modulated either sinusoidally or with pseudorandom noise. The cross‐correlation analysis of the unit discharge rate and the pseudorandom noise modulation of the stimuli showed that the dynamic properties determined from the responses to a single modulated excitatory tone (at CF), to a modulated excitatory tone together with an unmodulated inhibitory tone (above CF), and to a modulated inhibitory tone together with an unmodulated excitatory tone were almost identical with regard to latency as well as to delay of the peak of the cross‐covariance function. On the basis hereof it is inferred that the inhibition is either a cochlear phenomenon or that it is transmitted over pathways with identical temporal properties as those of the excitation. When 2 tones were presented simultaneously the modulation of the excitatory tone usually gave a higher degree of modulation of the discharge rate than did modulation of an inhibitory tone. Addition of an unmodulated inhibitory tone to a modulated tone at CF resulted in an extension of the range of intensities over which the maximal gain was relatively constant. In many units this range extended from about 10 dB above the unit's threshold to 60 dB or more above.
Consequence of Social Isolation on Blood Pressure, Cardiovascular Reactivity and Design in Spontaneously Hypertensive Rats
Authors: Hallbäck Margareta
Published: December 2008

Spontaneously hypertensive rats (SHR), which inherently display exaggerated cardiovascular defence reactions to environmental stimuli (Hallbäck and Folkow 1974), and normotensive control rats (NCR) were kept isolated after they were weaned to reduce such environmental influences which normally induce psychological activation. Mean arterial pressure was followed until 7 months of age, when the cardiovascular defence reactions to acute mental stress were compared and an analysis of cardiovascular design was made. The isolated SHR but not the isolated NCR, had significantly lower pressures than their unisolated controls. Likewise, judged by the relative weight of the left ventricle and the hemodynamically evaluated design of the hindquarter resistance vessels, the structural cardiovascular adaptation was about proportionally less pronounced in isolated than in control SHR. However, their cardiovascular responses to acute “psychological stress” were equally intense, and clearly exaggerated when compared with NCR. Thus, a prolonged reduction of excitatory environmental influences implies a relatively less pronounced development of hypertension in SHR, even though an inherent hyperreactivity concerning neurohormonal pressor responses to alerting stimuli is present. These findings stress the importance of interacting intrinsic‐hereditary and extrinsic neurogenic influences for the initiation of primary hypertension.
Distribution of an Adenohypophysial Constituent in the Body II. Quantitative Tissue Distribution in the Rat
Authors: Hall Håkan , Lakomaa Eeva , Kihlström Jan Erik
Published: December 2008

A peptide with a molecular weight of about 5 000 has previously been shown to affect the output of semen in frogs and probably also in mammals. This sperm‐releasing substance is not part of any known gonadotropic hormone. The tissue distribution of this substance has been investigated. The iodinated substance has been injected into rats and the radioactivity content of the different tissues has been determined. lodinated rat albumin has been injected into other rats, to determine the content of blood in the different tissues. A formula has been derived to obtain a figure for real accumulation, using the radioactivity content of the blood and of the tissues after injection of the sperm‐releasing substance and albumin, respectively. The sperm‐releasing substance is incorporated into the adenohypophysis. neurohypophysis. liver, kidney, lung, ovary, uterus and some male sexual organs. The causes for this distribution are discussed.
Effect of Alloxan‐diabetes on the Metabolism of Rabbit Colon Smooth Muscle
Authors: Arnqvist Hans J.
Published: December 2008

The metabolism of colon smooth muscle from normal and alloxan‐diabetic rabbits was studied in vitro. Glucose uptake, incorporation of glucose‐14C into glycogen and incorporation of leucine‐14C into protein were determined. These three parameters were all depressed in diabetic smooth muscle incubated in a medium containing 5.6 mM glucose. Raising the glucose concentration in the medium to 22.2 mM almost doubled the glucose uptake both in diabetic and normal smooth muscle and at this glucose concentration no significant difference in this parameter was found. Insulin (0.1 U/ml) added in vim) stimulated glucose uptake, incorporation of glucose‐14C into glycogen and incorporation of leucine‐14C into protein in diabetic colon smooth muscle. Insulin stimulated glucose uptake to the same degree in normal and diabetic colon smooth muscle, while its effect on glucose‐14C and Ieucine‐14C incorporation tended to be somewhat more pronounced in diabetic colon muscle.
The Influence of Acute Normovolemic Anemia on Cerebral Blood Flow and Oxygen Consumption of Anesthetized Rats
Authors: Borgström Lars , Jóhannsson Halldór , Siesjö Bo K.
Published: December 2008

The influence of acute normovolemic anemia on cerebral blood flow (CBF) and cerebral metabolic rate for oxygen (CMRO2) was studied in normocapnic rats under nitrous oxide anaesthesia. The arterial hemoglobin content was reduced to values of about 12, 9, 6 and 3 g.(100 ml)‐1 by arterial bleeding and substitution with equal volumes of homologous plasma. The CBF increased in proportion to the reduction in hemoglobin content to reach values of 500–600 per cent of normal at extreme degrees of anemia, but CMRO2 remained unchanged. Cerebral venous PO2 and oxygen saturation did not decrease below normal values, indicating that tissue hypoxia did not develop. However, since the increase in CBF at hemoglobin concentrations of below 9 g . (100 ml)‐1 was far in excess of that expected from the decrease in viscosity the results indicate that dilatation of cerebral resistance vessels occurred. This dilatation, which was obviously related to the fall in arterial oxygen content, cannot be explained by any of the current theories proposed to explain cerebral hyperemia in hypoxia.
The Distribution of Sodium in Aortic Walls from Spontaneously Hypertensive and Normotensive Rats
Authors: Jonsson Olof , Lundgren Yen , Wennergren Göran
Published: December 2008

The contents of exchangeable sodium, bound sodium and total water and the extracellular space of thoracic aortas from normotensive and spontaneously hypertensive rats were measured. The aortas from the hypertensive rats contained more sodium than those from the normotensive animals while the total water content and extracellular space in the two groups were the same. The capacity to bind sodium in an osmotically inactive form was greater in the aortas from the hypertensives than in those from the normotensives. The difference in binding capacity was of the same order of magnitude as the difference in sodium content, indicating that the excess sodium in the thoracic aortas from the hypertensive rats was osmotically inactive and thus unable to cause water logging.
Arterial Pressure, Cardiac Output and Systemic Resistance before and after Pithing in Normotensive and Spontaneously Hypertensive Rats
Authors: Albrecht I. , Hallbäck M. , Julius S. , Lundgren Y. , Stage L. , Weiss L. , Folkow B.
Published: December 2008

After complete cardiovascular denervation mean arterial pressure (MAP) falls to almost equally low levels in spontaneously hypertensive rats (SHR) and normotensive control rats (NCR). This has earlier been suggested to indicate a dominance of neurogenic mechanisms in established SHR hypertension.–In the present study, total peripheral resistance (TPR) remains, however, some 35 per cent higher in adult SHR than in NCR after pithing while cardiac output (CO), and stroke volume, is 35 per cent lower in SHR. These opposite differences in TPR and CO after denervation, resulting in equal MAP levels in SHR and NCR, seem rather to be a consequence of the rapidly established structural adaptation that affects all SHR high‐pressure cardiovascular sections. Thus, the SHR precapillary resistance vessels display thick‐ ened walls and luminal narrowing, which keeps TPR higher than in NCR even during maximal vaso‐ dilatation. Due to hypertrophy, the SHR left ventricle exhibits a reduced myocardial stretch for a given filling pressure and stroke volume is consequently reduced more than in NCR after complete denervation.–Paradoxically, therefore, rather than reflecting any dominance of neurogenic mechanisms in established SHR hypertension the MAP equalization in SHR and NCR after cardiovascular denervation emphasizes the hemodynamic importance of cardiovascular structural changes present in hypertension.
Studies of Some Twitch and Fatigue Properties of Different Motor Unit Types in the Ankle Muscles of the Adult Cat
Authors: Hammarberg C. , Kellerth J‐O.
Published: December 2008

Contractile responses of motor units in the gastrocnemius, soleus and pretibial flexor muscles of adult cats were elicited by intracellular stimulation of motoneurones. The motor units were classified into types FF, FR and S (Burke et al. 1971) and their responses to the same stimulation patterns as those used in a previous investigation of whole muscles (Hammarberg and Kellerth 1975 a) were studied. The duration of motoneurone afterhyperpolarization was short in both the fast twitch FF and FR units; it was longer in the soleus S units than in the S units of the pale muscles. Twitch time‐to‐peak was less than 30 ms in the FF and FR units, but exceeded 40 ms in the S units. Soleus S units were slower than S units of the pale muscles. Potentiation was observed in the gastrocnemius units, but not in the soleus S units. A short rest allowed fatigued extensor units of the FF and FR types to regain some contractile strength. This was less evident in the S units which, on the other hand, were extremely resistant to fatigue. Differences in response patterns between corresponding motor unit types of the flexor and extensor muscles were observed. A few fast twitch units were identified in the slow soleus muscle.
Effect of Bulbar Acidification on Gastric Acid Responses to Urecholine in Pavlov Pouch Dogs
Authors: Nilsson Göran
Published: December 2008

Dogs were provided with mucosal septal pouches of the fundic stomach and of the duodenal bulb. Gastric secretion was stimulated by intravenous infusion of submaximal doses of porcine gastrin or the stable choline ester Urecholine. Acid perfusion of bulbar pouches profoundly inhibited acid responses to gastrin. Bulbar acidification produced little or no reduction in acid secretion induced by Urecholine. Small doses of Urecholine do not release gastrin in the dog but may induce acid secretion, mainly by direct cholinergic stimulation of the HC1 glands. The fact that Urecholine‐induced acid secretion was not inhibited in the present experiments is consistent with the hypothesis that the bulbar mechanism does not interfere with cholinergic stimulation acting on the parietal cells.
Reversibility of Effects of Very Hypotonic Fluids on in Vitro Frog Gastric Mucosa: A Functional and Morphological Study
Authors: Helander H. F. , Sanders S. S. , Shanbour L. L. , Rehm W. S.
Published: December 2008

Functional and morphological properties of the in vitro frog gastric mucosa were studied during and after exposure to very hypotonic (≅ 25 mOsM) solutions. Within 20 min the acid secretory rate decreased to zero, but it returned to normal levels after isotonic fluids had been restored. The potential difference (PD) dropped within the first minutes after the exposure to hypotonic solutions, and became inverted. Following the return of isotonic conditions the PD increased to levels higher than in the controls. The electrical resistance increased about 10–fold during the hypotonic period, but decreased to near normal values when isotonic conditions were restored. By light and electron microscopy the cells of the hypotonic mucosae appeared greatly swollen, and the alterations were assessed by morphometric methods. The gland lumina were almost obliterated, and the lamina propria was reduced to about 60% of its former volume. After the return to isotonic conditions normal morphology was restored. It is conceivable that the great increase in resistance during the hypotonic period was caused by the occlusion of the gland lumina. Quantitative analyses of the Na, K, and C1 tissue concentrations indicated a large loss of these ions during the hypotonic state. Presumably the epithelial cells in the hypotonic mucosae avoid bursting by rapidly letting large numbers of ions exit, which results in a cellular osmolarity close to that of the bathing fluids.
Effect of Elevated Interstitial Pressure on the Renal Cortical Hemodynamics
Authors: Källskog Ö. , Wolgast M.
Published: December 2008

The influence of renal interstitial pressure on the resistance pattern within the superficial cortical vasculature has been investigated from determinations of I) the glomerular blood flow with a modified microsphere technique and 2) the intravascular hydrostatic pressures.

Interstitial pressure was monitored via a 50 μm PVC‐catheter placed into the subcapsular interstitial space. Two conditions were analyzed viz. a) elevation of iiretheral pressure to 20 mm Hg and b) venous stasis to 10–15 mm Hg. Both conditions produced an increase in the interstitial pressure from 1–2 mm Hg to about 5 mm Hg as well as an increased hilar lymph flow and protein flow of about the Same size. The vascular reactions were different, however. Urethcral stasis (but not the stasis of a single nephron) produced a decreased resistance in the afferent arteriolae with a concomitant increase in the pressures in the glomerular capillaries, and the peritubular capillary network. In contrast, venous stasis produced only small changes in the parameters studied but for the obvious rise in the peritubular capillary pressure.

The results suggest that factors other than the interstitial pressure are governing the afferent vascular tone; the tubular wall tension might he one of these factors.
Comparison of the Effects of Physical Exercise, Cold Acclimation and Repeated Injections of Isoprenaline on Rat Muscle Enzymes
Authors: Harri M. N. E. , Valtola J.
Published: December 2008

The metabolic effects on rat cardiac and skeletal muscle of a strenuous program of swimming, of cold acclimation and of isoprenaline treatment (0.3 mg/kg daily for 5 five‐day weeks) were compared. Exercised and cold‐exposed rats gained less body weight than did controls or isoprenaline‐treated rats. In all treated groups the heart and the interscapular brown adipose tissue hypertrophied. The size of the adrenals increased only in isoprenaline‐treated animals. Cold‐acclimation and physical training increased and isoprenaline treatment reduced or did not affect the activities of succinate dehydrogenase, rnalate dehydrogenase and citrate synthase of cardiac muscle. In skeletal muscle all treatments resulted in increased activities of these enzymes. Of the anaerobic enzymes analysed, only the activity of hexokinase increased in response to the treatments used. This increase was the same in cardiac as in skeletal muscle, but it was significantly greater with isoprenaline‐treatment than with training or with cold‐acclimation. The activities of lactate dehydrogenase and phosphofructokinase did not differ significantly. All treatments improved cold resistance, but only swimming exercise and cold acclimation significantly increased tolerance to exercise. It is concluded that prolonged stimulation of adrenergic β‐receptors by catecholamines is responsible for the metabolic changes observed.
Gastric Acid Secretion in a Teleostean Fish A Method for the Continuous Collection of Gastric Effluence from a Swimming Fish and its Response to Histamine and Pentagastrin
Authors: Holstein Björn
Published: December 2008

Gastric acid secretion has been measured in the codfish (Gadus morhua) equipped with a catheter draining the stomach, by titrating the water swallowed by the fish. Unstimulated acid secretion was found to be very low; in most fishes not exceeding 8 μmol H+/kg.h. Intramuscular injection of histamine evokes a dose‐dependent secretion of gastric acid, with a maximum acid output of 300 μmol/kg.h occurring with 10 mg/kg histamine dihydrochloride. No acid response was obtained with pentagastrin.
On the Mechanism of Inhibitory Action of Vibrations as Studied in a Molluscan Catch Muscle and in Vertebrate Vascular Smooth Muscle
Authors: Ljung Bengt , Hallgren Per
Published: December 2008

In previous studies longitudinal vibrations have been found to reduce active force development in smooth muscle, possibly due to a direct action on the contractile mechanism. In the present experiments the inhibitory effect of vibrations on isometric tension was studied in isolated preparations of the rat portal vein, the rabbit thoracic aorta and the anterior byssus retractor muscle (ABRM) of the Mytilus edulis, The results demonstrate that vibrations of appropriate frequency and amplitude caused prompt inhibition of contractile tension and that complete recovery of active force normally occurred after cessation of vibration in vertebrate smooth muscle as well as during the phasic contraction of ABRM. However, in the “catch” of the ABRM there was no regain in force following the vibration induced inhibition. The contractile proteins are considered to be in a locked state during the catch situation. Thus, this contracted state seems to be released by vibrations. It is therefore concluded that vibrations do interfere with the interrelationship between the myofilaments. This conclusion supports the previously forwarded hypothesis that vibrations act by increasing the rate of detachment of actin‐myosin crosslinks in vertebrate smooth muscle.
Thermoregulation during Static Work with the Legs
Authors: Nielsen Bodil
Published: December 2008

Sustained static work with the legs, i.e., holding a weight of about 10% of maximal isometric strength for 25 min was compared to dynamic exercise on a bicycle ergometer causing the same rate of heat production.

In the static work the subjective feeling of exertion was very high and the effort maximal. The pronounced increase in heart rate and blood pressure and a typical flush of the face and chest (flush areas) indicated a high sympathetic tonus. Plasma catecholamine levels were 1.3 times higher (significant at the P ≤ 0.05 level) after static work than after dynamic work. Although the sustained static work was nearly maximal, the rate of increase in sweating and the change in core temperature during work were not different from the responses to dynamic work.
Synthesis of Brain‐Specific Acidic Proteins in Rat and Mouse Cerebral Slices
Authors: Wroński Andrzej , VON DER DECKEN ALEXANDRA
Published: December 2008

Optimal conditions for incorporation of radioactive amino acids into protein by slices of brain have been established. Protein synthesis continued for at least 4 h at 35°. The highest incorporation of amino acids into protein was obtained with 20–50 mg wet weight per ml incubated at pH 7.1. After incubation of 500 mg of slices acidic proteins were separated by saltfractionation and electrophoresis on 14% polyacrylamide gel. The most acidic band was shown to contain S‐100 protein. Identification was solubility of the protein in 100% (NH4)2SO4, electrophoretic mobility at pH 8.9, precipitation with specific antibodies, and 2‐dimen‐sional electrophoresis in polyacrylamide gel. The protein band was insoluble in 50 % methanol and contained between 0.06 and 0.2% of the radioactivity present in the total soluble proteins; while other well separated acidic proteins contained about 10 times the radioactivity of S‐100 protein.
On the Effects of Gymnemic Acid in the Hamster and Rat
Authors: Hellekant Göran , Gopal V.
Published: December 2008

The gustatory activity of the chorda tympani proper nerve has been recorded before and after the application of gymnemic acid to the tongue of hamster and rat. Concentrations of pure gymnemic acid ranging from 1 mg/ml to 10 mg/ml have been used. In the hamster gymnemic acid suppressed the response to solutions of sucrose especially, but it also caused, at higher concentrations, a general suppression of the taste response. The depression caused in the response to sucrose was directly related to the strength of the gymnemic acid and inversely to that of the sucrose solution. In the rat a suppression of the response to saccharin was obtained but no suppression of the taste response to sucrose by gymnemic acid was observed.
Dynamic Properties of Primary Auditory Fibers Compared with Cells in the Cochlear Nucleus
Authors: Møller Aage R.
Published: December 2008

The dynamic properties of the responses of single primary auditory fibers were compared with those of single cells in the cochlear nucleus. The stimuli were tones (at the unit's characteristic frequency, CF) that were amplitude‐modulated with pseudorandom noise. The dynamic properties were described by the cross‐covariance and integrated cross‐covariance functions between the recorded discharge rate and the modulation. These two measures have earlier been shown to be valid approximations of the system's impulse and step response function, i.e. the change in discharge rate in response to a short impulsive increase (or decrease) in the stimulus intensity and a step increment (or decrement) in the stimulus intensity. The cross‐covariance function computed from the responses of fibers had a narrower peak than that of cells indicating that a brief change in stimulus intensity gives rise to a faster change in the discharge rate of fibers than that of cells. The modulation of the discharge rate of cells for a certain degree of amplitude modulation of the sound is usually greater than that of fibers. The range of stimulus intensities where a change in stimulus intensity gives rise to a change in discharge rate is smaller for fibers (about 30 dB) than what was shown earlier for cells (70–80 dB). The cross‐covariance function computed from the slow wave responses recorded from the surface of the cochlear nucleus in response to an amplitude‐modulated tone has individual peaks that reflect distinct classes of units with regard to latency of unit discharges.
Molecular Forms of Gastrin in Antral Mucosa, Plasma and Gastric Juice during Vagal Stimulation of Anesthetized Cats
Authors: Uvnäs‐Wallensten K. , Rehfeld J. F.
Published: December 2008

Gastrin was released by electrical vagal stimulation in anesthetized cats. Antral mucosa, blood and gastric juice samples collected during vagal stimulation were subjected to gel filtration in order to characterize the different molecular forms of gastrin. In antral mucosa component III (gastrin‐17) predominated. Besides, the antrum contained 5 per cent component II (gastrin‐34, “big” gasirin), I per cent component I and trace amounts of component IV (gastrin‐14 or “mini” gastrin). Immediately after vagal stimulation, component III (gastrin‐17) appeared in the gastric venous effluent followed within a few minutes by component IV (gastrin‐14). Component I and II (gastrin‐34) were not detectable in any of the plasma samples. We suggest that component III (gastrin‐17) is released from the antral mucosa and is then rapidly metabolized to component IV (gastrin‐14) possibly to a significant extent in the fundic region of the stomach. Large amounts of component III (gastrin‐17) were found in the vagally‐induced gastric juice. Only very small amounts of degradation products were present, indicating that cat gastrin is relatively resistant to peptic degradation and acid hydrolysis.
Liver Hemodynamics and Liver Function in Cats during Graded Hypoxic Hypoxemia
Authors: Larsen Jens Anker , Krarup Niels , Munck Anders
Published: December 2008

In 15 cats, anesthetized with chloralose and curarized, liver hernodynamics and liver function were followed during graded hypoxic hypoxemia. Hepatic arterial and intrahepatic portal venous conductance were not influenced by hypoxia, whereas severe hypoxemia increased gastrointestinal conductance. Total liver blood flow remained constant and hypoxemia was compensated for by an increase in hepatic extraction of oxygen approaching 100% Only when the hepatic venous PO2 fell below 5–10 mmHg did hypoxemia decrease liver function. The results indicate that the sinusoidal perfusion is homogeneous.
Convergence on Interneurones Mediating the Reciprocal Ia Inhibition of Motoneurones I. Disynaptic Ia Inhibition of Ia Inhibitory Interneurones
Authors: Hultborn H. , Illert M. , Santini M.
Published: December 2008

Interneurones identified as mediating the disynaptic reciprocal Ia inhibition of motoneurones (referred to as “Ia inhibitory interneurones”) were recorded in the lumbar spinal cord of the cat. It was revealed that the Ia inhibitory interneurones themselves receive disynaptic Ia inhibition. The muscles from which this inhibition is evoked are strictly antagonistic to those supplying their Ia excitation. Similar to the Ia inhibition in motoneurones the Ia inhibition in the Ia inhibitory interneurones is decreased when preceded by an antidromic stimulation of ventral roots. Furthermore, transmission of Ia inhibition to the Ia inhibitory interneurones is facilitated from ipsilateral and contralateral primary afferents as well as several supraspinal pathways analogous to earlier findings for the Ia inhibition of motoneurones. The pattern and control of the Ia inhibition of motoneurones and of Ia inhibitory interneurones display so striking similarities that it is suggested that identical interneurones are responsible. The conclusion thus emerges that “opposite” Ia inhibitory interneurones (i.e. interneurones monosynaptically connected to antagonistic muscles) are mutually inhibiting each other. The functional significance of this organization is discussed.
Towards a Valid Technique of Sampling Fish Muscle to Determine Redox Substrates
Authors: Börjeson Hans , Fellenius Erik
Published: December 2008

The redox substrates—lactate, malate, α‐glycerophosphate, dihydroxy acetonephosphate and pyruvate—have been determined in liver and muscle tissue from young salmon. The redox quotients have also been calculated. The freeze clamping technique was used and reliable samples of fish muscle for the determination of lactate were obtained with the aid of a pair of pliers with a gear mechanism. It was established that the lactate content in the body muscle is in close agreement with that in the blood from rested salmon parr. The concentrations of redox substrates are in good agreement with those found in mammalian tissue. The determination of the content of glycogen in fish muscle is discussed in the light of the results obtained in this study.