bluuebunny/crossref_metadata_2025 huggingface dataset:
Permeability of Brain Capillaries to Hexoses and Pentoses in the Rabbit
Authors: Agnew W. F. , Crone Christian
Published: December 2008

The initial loss in the rabbit brain of non‐electrolytes injected into the carotid artery was measured with ‘Indicator Diffusion’ technique, 3–0–methyl‐D‐glucose shared with D‐glucose the ability to pass into the brain by a mediated transport mechanism. The rate of transport of the following substances could not be distinguished: D‐mannose, D‐galactose, D‐arabinose and 1)‐ribose. They all penetrated more slowly than D‐glucose.

D‐mannitol was also lost from the blood during the passage through the brain. This observation, together with the known inability of D‐mannitol to pass the blood‐brain barrier, suggests that the loss takes place into the endothelial cytoplasma. Thus the basal plasma membrane of the endothrlial cells together with the basal membrane proper may define blood‐brain barrier chararteristirs.
Effect of Prolonged Heavy Exercise on Renal Function and Urinary Protein Excretion
Authors: Castenfors Jan , Mossfeldt Folke , Piscator Magnus
Published: December 2008

The urinary proteins in normal men participating in an 85–kilometre ski race held in 1964 and 1965 were examined by electrophoresis, immunoelectrophoresis and gel filtration. The urinary escretion of protein, glucose, ribonuclease and α‐amino acid‐N was also studied. In conjunction With the 1965 race additional studies were made of urine flow, free water clearance, creatinine clearance sodium, phosphorus and potassium exeretion and examination of urinary sediment. There was a significant increase in total protein and albumin excretion during the race. The protein excretion varied considerably from one individual to another. In 9 subjects who participated in both years the protein excretion, and also the peremtage albumin found by electrophorcsis, showed a significant correlation between the two years. The excretion of glucose and α‐amino acids, which are freely filtrable in the glomerule, was not significantly changed. Sor was the exeretion of the low molecular wright protein, ribonuclease. which may be expected to be almost completely filtrable. This suggests that tubular reabsorption is mainly unchanged during exercise, but that glomerular prmirability for relatively large molecules is increased. Creatinine clearance decreased during the race. Urine flow and sodium exeretion decreased slightly during exercise. Potassium exeretion increased both during and after the ski race. Urinary sediment showed increased amounts of red and white cells, and hyalinc casts.
Recurrent Discharges Studied in Single Units of Laryngeal Muscles
Authors: Mårtensson A.
Published: December 2008

It has previously been shown that electrical stimulation applied to the intact laryngeal inuscle nerves of anesthetized dogs elicits. besides the direct response. also a secondary. centrally relayed response (Mårtensson 1963). The first section of the present paper describes studies of these responses in single units and provides conclusive evidence that the centrally relayed response is not a proprio‐ceptive reflex discharge but represents a recurrent discharge transmitted through antidromically invaded inotoneurons; it is shown that when the direct response consists of a discharge in a single motor unit the secondary response invariably represents a discharge in the same unit. and that the centrally relayed response is transmitted by nerve impulses travelling at the same velocity in the centripetal and centrifugal direction. In the second section of the paper, experimental evidence is presented that the recurrent discharges thus recorded in the laryngeal muscles obey the laws postulated for the generation of such discharges in spinal motoneurons (Eccles 1955).
Myogenic Response of Resistance Vessels and Precapillary Sphincters in Skeletal Muscle during Exercise
Authors: Lundvall Jan , Mellander Stefan , Sparks Harvey
Published: December 2008

Capillary filtration coefficient (CFC), reflecting precapillary sphincter tone, and venous outflow of cat lower leg muscle were observed at various transmural pressures before and during muscle work. Increasing transmural pressure in resting muscle 30 mm Hg caused a 35 per cent decrease in CFC, indicating increased tone of precapillary sphincters and, on the average, no change in blood flow, indicating that the increased active tone of resistance vessels closely balanced passive distention. During exercise at 1 twitch/sec, elevating transmural pressure decreased CFC by 50 per cent and increased flow 38 per cent indicating that while precapillary sphincters were still responsive, metabolic demand caused the resistance vessels to behave passively. At 4 twitches/sec the active response of the precapillary sphincters was present, although less marked, whereas the passive behaviour of the resistance vessels was even more pronounced than at 1 twitch/sec. Myogenic autoregulation of filtration exchange via alteration of precapillary sphincter tone may be an important factor preventing gross edema in the legs of upright man during exercise.
Effect of Dihydralazine on Plasma Renin Activity and Renal Function during Supine Exercise in Normal Subjects
Authors: Božović Ljubomir , Castenfors Jan
Published: December 2008

Plasma renin activity, clearance of inulin (Cin) and para‐aminohippuric acid (Cpah), urinary sodium and potassium excretion during supine exercise were studied in normal healthy men. 8 subjects were treated during exercise with dihydralazine (Nepresolin® i.v.) and 8 subjects were untreated (control group). In the untreated subjects there was a statistically significant decrease in Cpahand increase in filtration fraction. The decrease in Cparduring exercise was less in the dihydralazine‐treated group and the increase in filtration fraction almost inhibited. Urinary sodium excretion decreased significantly in both groups during exercise but returned slowly to pre‐exercise level in the dihydralazine group. Plasma renin activity increased during exercise in both groups, most markedly in the dihydralazine group. After exercise plasma renin activity decreased to pre‐exercise level in the control group but continued to increase in the dihydralazine group in spite of the increased renal blood flow. The findings indicate more marked sympathetic activity in the dihydralazine group and it is suggested that the sympathetic nervous system may have a direct influence on renin release irrespective of its renal hemodynamic action.
Effect of Ganglionic Blocking on Plasma Renin Activity in Exercising and Pain‐Stressed Rats
Authors: Božović Ljubomir , Castenfors Jan
Published: December 2008

The effect of ganglionic blocking on piasma renin activity and plasma sodium concentration during exercise and pain stress were studied in rats. 20 female albino rats were exercised by swimming and 16 received intramuscular injections of 1 ml 10% NaCl. Half of the animals in each group were pretreated with a ganglionic blocking drug (Ansolysen®). In both groups there was a significantly lower plasma renin activity in the ganglion‐blocked animals compared with their untreated controls, which indicates the importance of the sympathetic system for renin release. The findings suggest that changes in plasma sodium concentration are of minor importance compared with sympathetic activity.
The Effects of Varying the Extracellular Potassium Concentration on the Secretory Rate and on Resting and Secretory Potentials in the Perfused Cat Submandibular Gland
Authors: Petersen Ole Holger , Poulsen Jørgen Hedemark
Published: December 2008

Lundberg presented the hypothesis that the secretory potentials in salivary glands were due to an active transport of chloride ions. This transport should be responsible for the formation of the saliva. Recently a different hypothesis has been proposed by Imai, who postulated that the secretory potentials were caused by an increased permeability of the cell membranes to potassium ions. The present investigation was undertaken to test Imai's hypothesis. It was found that the secretory potentials and the secretory rate depended in very much the same way on the extracellular potassium concentration. This gives further support to Lundberg's hypothesis.
Circulatory and Behavioural Effects on Electrical Stimulation of the Sympathetic Vasodilator Areas in the Hypothalamus and the Mesencephalon in Un anesthetized Dogs
Authors: Bolme Per , Ngai S.H. , Uvnäs Börje , Wallenberg Lars R.
Published: December 2008

Blood prrssure, heart rate, blood flow to the hind limb and behaviour wcrv studied in conscious dogs during topical stimulation of the sympathetic vasodilator outflow area in the hypothalamus and the mesencephalon. The responses obtained on stimulation were: a rise in blood pressure, tachycardia and also an increasr in hind limb blood flow which could bc abolished by atropinc. The effects on circulation caused by stimulation were essentially the same in the conscious and the anaesthetized dog. The behavioural changes on stimulation were relatively small and consisted of variations in the degree of alertness. In many experiments marked circulatory responscs were obtained on stimulation without any apparent behavioural reactions. Whether these findings indicate that the cholinergic vasodilator system acts more generally in circulatory homeostabis or is restricted to participation in specific situations ase.g. adjustments preparatory to niuacle effort. is discussed.
Projections of the Eye and the Neck Region on the Anterior Suprasylvian Cerebral Cortex of the Cat
Authors: Landgren S. , Silfvenius H.
Published: December 2008

The overlap between projections of visual, auditory, cutaneous and muscle afferents to the cerebral cortex of the anterior suprasylvian sulcus was studied in cats anesthetized with chloralose. The visual projections were found near the junction between the anterior and the middle suprasylvian sulcus. They overlapped in rostral direction with the auditory projection area in the lower bank of the anterior sulcus. The overlap was, however, not complete and large click potentials, but no response to a light flash, were recorded in the lower bank just caudal to the locus of the Group I muscle afferents. Low threshold cutaneous and high threshold muscle afferents from the neck projected to the anterior suprasylvian and ecto‐sylvian gyri and to the upper bank of the anterior suprasylvian sulcus. Low threshold rnuscle and cutaneous neck afferents projected to the postcruciate dimple. A hypothesis concerning the function of this cortical region is discussed.
Formation of Extracellular Adenosine Triphosphate by Yeast Cells
Authors: ÅGren Gunnar , Ronquist Gunnar
Published: December 2008

Yeast cells were incubated with the necessary substrates and cofactors of the glyceraldehyde‐3‐phosphate dehydrogenase and phosphoglycerate kinase reactions (complete system) and also with an incomplete system lacking the phosphorylaied substrates and cofactors. Ten times more ATP was formed by the yeast cells incubated with the complete system as compared with those incubated with the incomplete system. All the resulting ATP formed by the phosphorylated substrates and cofactors present in the complete system could be recovered in the extracellular medium. Only an insignificant part of this ATP has probably been formed by enzymes of intracellular origin. It is reasonable to assume that most of the ATP present in the extracellular medium has been formed by the enzymes located on the surface of the yeast cells.
Proximal Luminal Volume and Fluid Reabsorption in the Rat Kidney1
Authors: Baines Andrew D. , Gottschalk Carl w. , Leyssac Paul P.
Published: December 2008

The relationship between proximal luminal volume and proximal salt and water reabsorption was studied in 21 non‐diuretic anesthetized male rats. Luminal diameters were measured in enlarged photographs of the surface of the capsulated kidney. Proximal reabsorption rates were estimated from Cin, which changed spontaneously in the range 0.4–1.6 ml/min g kidney weight (k.w.). Cin was further reduced in eight rats by compression of the renal artery. The mean proximal luminal diameter was 18.7 μ without compression of the renal artery and 19.6 μ during compression. There was no consistent relationship between estimated proximal reabsorption rate and proximal luminal diameter. It is concluded that proximal tubular volume was not the prime determinant of proximal salt and water reabsorption rate in rats under the conditions of these experiments.
Formation of Extracellular Adenosine Triphosphate by Human Erythrocytes
Authors: Ronquist Gunnar
Published: December 2008

The formation of extracellular adenosine triphosphate by human erythrocytes was studied. The red cells were incubated with (32P)‐orthophosphate, together with all necessary substrates and co‐factors of the glyceraldehyde‐3‐phosphate dehydrogenase and phosphoglycerate kinase reactions (complete system), and also with an incomplete system lacking the phosphorylated substrates and cofactors. Finally, the red cells were incubated with the complete system lacking only one phosphorylated cofactor. All incubations were performed under isotonic conditions.

At I min incubation, three times more AP32P was formed by the red cells incubated with the complete system than with those incubated with the incomplete system. All the resulting AP32P formed by the added phosphorylated substrates and cofacton present in the complete system could be recovered in the extracellular medium. Only an insignificant part of this AP32P was probably formed by enzymes which were eluted out into the surrounding medium. It is therefore reasonable to infer that most of the AF32P present in the extracellular medium was formed by the enzymes located on the surface of the red cells. No AP32P was found in the extracellular medium of red cells incubated with the incomplete system, nor with the complete system lacking only one phosphorylated cofactor. Thus, none of the intracellular ADP, NAD+ or glyceraldehyde‐3‐phosphoric acid could be utilized in ATP formation on the red cell surface.
NUCLEIC ACIDS IN EXPERIMENTAL GRANULOMA
Authors: AHONEN JUHANI
Published: December 2008

The purpose of the work was to develop methods for the extraction and fractionation of nucleic acids from experimental granulomas, and to study nucleic acids at various phases of development of granulomas in order to collect information about the changes that accompany fibroblast differentiation.
Some Factors Influencing the Stimulatory Effect of Ethanol on Gastric Acid Secretion during Antrum Application1
Authors: Elwin Carl‐Eric
Published: December 2008

Variations in gastric secretory response to antral application of ethanol were studied in Heidenhain and Pavlov pouch dogs with isolated, innervated antral pouch, to disclose the influence of instillation pressure, temperature, concentration, pH and ion composition. Secretory response increased in 2 of 5 dogs and remained unchanged in 3 dogs during rise of installation pressure from 0 cm H2O to 20–30 cm H2O. Secretory responses were essentially alike, whether alcohol solutions were administered at room temperature or at body temperature. Threshold stimulatory concentration was 2–4% (v/v), optimal effect occurred at 8–16%, a decrease was usually observed at 32%. Antrum pouches were perfused with buffered ethanol solutions at pH values between 7.0 and 1.0. No significant difference of the stimulatory effect was noted within the pH range 7.0–3.0. At pH 2.0 the stimulatory action was decreased by about 40% and at pH 1.0 almost totally suppressed. The slope of the pH curve seems to be independent of the ethanol concentration. The pH curves for the stimulatory effect of alcohol in the antrum and for vagus stimulation are almost identical. The ethanol effect was inhibited by high concentrations of K+ and Ca++ but uneffected by corresponding concentrations of Na+ and Mg++.
Three Different Systems of Monoamine‐Storing Cells in the Gastrointestinal Tract of Fetal and Neonatal Rats
Authors: Håkanson R. , Owman Ch. , Sjöberg N.‐O.
Published: December 2008

The development of three monoamine‐storing cell systems in the wall of the duodenum, glandular portion of stomach, and ileum has been followed histochemically in fetal and newborn rats, and compared with the number and characteristics of such cells in adults. 5‐Hydroxy‐tryptamine can be demonstrated in mast cells and enterochromaffin cells already a few days before birth. Part of the mast cell population, i.e. the one which in adult animals is found as “atypical” mast cells near the mucosal surface, is able to take up high amounts of L‐DOPA. “Enterochromaffin‐like” cells, exclusively found in the oxyntic gland area of the gastric mucosa, are also able to take up and, probably decarboxylate, L‐DOPA already at birth. Their number increases progressively in the following stages. Gastric DOPA decarboxylase activity is high already at a stage when the capacity to store monoamines has not yet developed in the enterochromaffin‐like cells, the system of monoamine cells quantitatively dominating in the stomach wall. The finding suggests that DOPA decarboxylase occurs also in other cell systems, such as mast cells and enterochromaffin cells, which are capable of storing monoamines earlier than the enterochromaffin‐like cells. The activity of gastrointestinal DOPA decarboxylase reaches adult levels already by the time of birth, and is probably primarily associated with the two systems of enterochromaffin and enterochromaffin‐like cells.
Vago‐Vagal Reflex Relaxation of the Stomach in the Cat
Authors: Jansson Gunner
Published: December 2008

In acute experiments on chloralosed cats gastric motility was recorded with a rubber balloon system kept at constant intragastric pressure under experimental conditions not requiring abdominal surgery.‐Electric stimulation of the central end of either a small vagal branch at the level of the diaphragm or of one vagal nerve at the level of the neck, while the opposite vagal nerve was left intact produced profound reflex relaxation of the stomach. Also the efferent pathway of the relaxatory reflex was in the vagal nerves.‐The reflex relaxation persisted after administration of atropine, which shows that it was not due to reflex suppression of prevailing activity of the vagal cholinergic motor fibres. It was also independent of adrenergic mechanisms, since it persisted after administration of guanethidine in doses known effectively to block the adrenergic intestino‐gastric inhibitory reflex. This vago‐vagal relaxatory reflex response thus showed the same characteristics as the gastric response elicited by efferent stimulation of the high‐threshold vagal relaxatory fibres.‐It is concluded that this vago‐vagal reflex originates, at least partly, from abdominal structures, with the efferent pathway consisting of the relaxatory, high‐threshold fibres producing pronounced gastric relaxation. This vago‐vagal relaxatory reflex may be involved in receptive relaxation of the stomach.
Effects of Bicarbonate and Thiocyanate on Fluxes of Na and K, and on Glucose Metabolism of Actively Transporting Human Red Cells
Authors: Wieth Jens Otto
Published: December 2008

It has been shown in a previous work that sodium influx is trebled, whereas potassium efflux is slightly reduced, when erythrocytes are suspended in a 142 mM bicarbonate medium containing ouabain. The present work deals with the active transport of sodium and potassium occurring in the presence of 142 mM bicarbonate (38° C, pH 7.40). Sodium influx and potassium efflux were unaffected by the removal of ouabain, whereas sodium efflux, potassium influx, and glucose metabolism were all strongly stimulated. The relation between ouabain sensitive ion transport and the calculated extra formation of ATP was 3.1 moles Na/mole ATP and 2.3 moles K/mole ATP, in agreement with values previously found on red cells transporting Na and K in plasma. Red cells incubated in the bicarbonate medium accumulated potassium until extracellular potassium concentration had been reduced to 1.8–2 mM. The normal volume regulation of the cells was severely interfered with, because accumulation of sodium and potassium was accompanied by a net flux of water of 6 g per meq cation. All effects observed could be interpreted to be secondary to the increased sodium influx, leading to an increase of intracellular sodium concentration, which in turn stimulated active cation transport, thereby accelerating the rate of ATP turn‐over. The properties of the ouabain sensitive transport mechanism were not affected by the presence of bicarbonate.

Both potassium efflux and sodium influx are increased by 200–300 per cent in the presence of 120 mM thiocyanate. It was found, however, that active cation transport is not stimulated in a 120 mM thiocyanate medium. On the contrary the ouabain sensitive ion transport was steadily decreasing during incubation in spite of conditions otherwise favouring transport of Na and K, i.e. increasing extracellular potassium and intracellular sodium concentrations.
A Sound‐Attenuating, Electrically Shielded Chamber for Experiments in Sensory Physiology
Authors: Bergström R. M. , Blåfield R. , Fruhstorfer H. , Hytönen Y. , Jauhiainen T.
Published: December 2008

The construction of a sound‐attenuating, electrically shielded chamber for experiments in sensory physiology is reported in short. The values of sound attenuation are given. Electrical shielding and connection to the laboratory computer are explained.
Tubular Sodium Reabsorption and the Regulation of Renal Hemodynamics. The Effect of Hypertonic Saline Infusion on Renal Vascular Resistance
Authors: Aperia Anita C. , Liebow Averill A. , Roberts Lathrop E.
Published: December 2008

The hemodynamic response following saline loading was found to differ from that induced by the saluretic agent, chlorothiazide, which causes vasoconstriction. When hypertonic NaCl was infused into the renal artery until a profuse sodium diuresis was obtained, and the infusion then interrupted, CNa/CIn remained elevated for 60–80 min. During this period the renal vascular resistance did not change significantly and the glomerular filtration rate tended to rise as compared with the control periods. This is contrary to what has previouly been found during chlorothiazide administration, where renal vascular resistance was significantly correlated with CNa/CIn. A hypertonic saline load blocks Na reabsorption in the proximal tubules, chlorothiazide mainly in the distal tubules. It was therefore concluded that it is a reduction of movement of Na into the distal tubule cells, specifically the macula densa, rather than the increased Na concentration of the distal tubular fluid that is responsible for the vasoconstrictive effect of chlorothiazide.
Relationship between Aortic Diameter and Aortic Baroreceptor Activity in Normal and Hypertensive Rabbits
Authors: Aars Harald
Published: December 2008

Studies of aortic nerve activity (Aars 1968a), and the load/length relationship of strips from the aortic wall (Aars 1968b), have suggested that the hypertensive resetting of baroreceptor activity is due to changes in the aortic wall. In nine normal and four hypertensive rabbits, diameter of the ascending aorta, measured with an ultrasonic gauge, was therefore recorded together with aortic baroreceptor activity. Aortic nerve activity was closely related to aortic diameter in individual rabbits, but wide variations in pressure/diameter relationships made it difficult to compare diameter and activity in a group of rabbits. Assuming that stretching of the receptor area would be almost equal in all rabbits at the inflexion point of their pressure/diameter curves, the diameter corresponding to inflexion point of the curve for dynamic elastic modulus was used as reference diameter. Plotted against per cent of this diameter, the nerve activity showed acceptable uniformity in the group of normal rabbits, and observations in hypertensive rabbits showed less deviation from the normal. The uniformity was further improved by allowing for variations in diameter pulsations. It was therefore concluded that the hypertensive resetting of aortic baroreceptor activity was predominantly due to altered distensibility of the aortic wall.
Electrical Stimulation of a Human Ventrolateral‐Subventrolateral Thalamic Target Area
Authors: Johansson Gunnar G.
Published: December 2008

A ventrolateral‐subventrolateral thalamic target area was electrically stimulated in connection with stereotaxic neurosurgery in 20 alert Parkinsonian patients and in 4 patients with hereditary intention tremor. The study forms part of a larger investigation concerned with the effect of different stimulus parameters on the clinical responses evoked by stimulation. Here unidirectional square wave pulses with a constant peak current and repetition frequencies ranging from 1 to 200 pulses per second were applied. The stimulation was kept at the threshold for clinical responses by balancing the different repetition frequencies with the pulse duration. Stimulation elicited motor and “sensory” responses. The character of the responses depended on the pulse repetition frequency used. The localization in the body of the projected threshold responses, on the other hand, depended on the pulse duration used. The pulse duration‐pulse repetition frequency relationship at the threshold for evoking clinical responses is shown. The results are discussed.
Effect of Acid in the Duodenal Bulb on Gastric Secretory Responses to Insulin Hypoglycemia1
Authors: Nilsson Göran
Published: December 2008

Gastric acid secretion was stimulated by insulin hypoglycemia in Pavlov pouch dogs with isolated pouches of the duodenal bulb. Perfusion of the duodenal bulb with 0.1 N HCI abolished the secretory response to a low dose of insulin (0.2 I.U. per kg b.w.), whereas the responses to higher doses (0.4 and 0.8 I.U. per kg b.w.) were only partially inhibited. It is suggested that the bulbar mechanism inhibits secretory responses to insulin hypoglycemia by interference with the stimulatory action of gastrin.
Evidence for a Hypothalamic Control of Renal Sodium Excretion
Authors: Andersson B. , Dallman M. F. , Olsson K.
Published: December 2008

Slow infusions (7.5 μl/min) of hypertonic NaCl into the 3rd brain ventricle of goats maintained on a NaCl‐supplemented diet provoked natriuresis reaching maximum about 70 min after onset of the infusions. The natriuresis was less pronounced in animals receiving no dietary NaCl‐supplementation. The magnitude of the natriuretic response was dependent on the molarity of the NaCl infused and on infusion duration. A much smaller relative increase in K excretion, reaching peak values 20 min before maximum natriuresis, also occurred. Aldosterone treatment did not prevent the natriuretic response and it could be elicited in diabetes insipidus animals, showing that release of posterior pituitary hormones was not essential. Determinations of inulin clearance (CIn) indicated that glomerular filtration rat (GFR) increased and that relative reabsorption of Na+ decreased during the natriuresis.

Similar intraventricular infusions of hypertonic NH4Cl resulted in greatly diminished renal Na+ excretion lasting for about 2 hrs. Such infusions also delayed by 90 min the normal natriuretic response to an intravenous NaCl load. CIn determinations indicated that a diminished GFR may have contributed to this reduction in renal Na+ excretion. The results indicate that renal Na+ excretion is under hypothalamic control in the goat. Possible mechanisms for this control are discussed.
Transient Transmembrane Water Movements in Crayfish Axons Detected by Transmitted Light Interference Microscopy
Authors: Lieberman E. M.
Published: December 2008

Transmitted light interference microscopy is shown to be a sensitive technique for detecting email transient changes in optical path differences of axons during and following electrical stimulation. It is tentatively concluded that water enters the axon during and following tetanizing stimulation and that this event is in accord with earlier findings concerning opacity changes under similar experimental conditions. It was further demonstrated that the membrane of the axon is normally under a hydrostatic pressure difference of approximately 2 cm of H2O and this may be a contributing factor to the optical properties of the axon during the excitation process.
Descending Monosynaptic and Reflex Control of γ‐Motoneurones
Authors: Grillner S. , Hongo T. , Lund S.
Published: December 2008

The supraspinal and reflex control of γ‐motoneurones has been studied with intra‐ and extracellular recording from lumbosacral γ‐motoneurones in the cat. Monosynaptic EPSPs were recorded in some γ‐motoneurones on stimulation of the brain stem. These effects were evoked from the Deiters' nucleus and from fibres descending in the medial longitudinal fascicle probably originating in the pontine reticular formation. Previous investigations have revealed monosynaptic connections to α‐motoneurones from these regions and our results suggest parallel effects to α‐ and part of the γ‐motoneurone population supplying one muscle. Indirect evidence suggests that this monosynaptic effect is exerted only on static γ‐motoneurones, thus implying a linkage between the descending monosynaptic control of α‐ and static γ‐motoneurones via these pathways. The reflex effects to γ‐motoneurones have been studied with graded electrical stimulation of ipsi‐ and contralateral hindlimb nerves. Five γ‐motoneurones, presumably all belonging to extensor motor nuclei, were found to receive IPSPs from group I afferents and it is suggested that only static γ‐motoneurones are influenced. It has not been possible to decide if these IPSPs are evoked from Ib or Ia afferents. The reflex effects from group II and III muscular afferents, joint and cutaneous afferents seem to conform to the effects evoked in α‐motoneurones from these afferents.
Brain Monoamines in the Temperature Acclimation of Mice
Authors: Harri M. , Tirri R.
Published: December 2008

The brain 5‐hydroxytryptamine (5‐HT) and noradrenaline (NA) levels were determined fluorimetrically from mice during prolonged exposure to cold or heat. The NA level did not change until at extreme ambient temperatures, in which cases, especially in heat, a marked decrease was observed. In cold environment the 5‐HT level decreased after an initial short increase. However, within one day the initial control level was reached again. In warm environment the changes were reversed. Some depletion experiments, where an inhibitor of 5‐HT synthesis was used, showed that the activity of brain 5‐HT neurons decreased for some days in cold, but returned gradually to the control level after the animals had acclimated to cold.
Cerebrospinal Fluid Perfusion, A Method for the Study of Neurosecretory Organs
Authors: Hirvonen J. , Karlsson L. K. J. , Salorinne Y.
Published: December 2008

The cerebrospinal perfusion method was applied for the study of the hypothalamo‐neurohypophyseal secretory system and subcommissural organ in the cat and rat. The artificial cerebrospinal fluid was introduced into the lateral ventricle and taken out of the suboccipital cisterna. Hyperkalemic (8 meq/1) perfusion fluid effected a decrease of the aldehyde‐fuchsin‐positive material in the subcommissural organs of the cats and rats. Hyperosmotic perfusion fluid had such an effect neither on the neurohypophysis nor the subcommissural organ. The method seems usefull for the study of the cellular reactions of the neurosecretory organs in vivo.
Renal Autoregulation during Infusion of Noradrenaline, Angiotensin and Acetylcholine
Authors: Kiil F. , Kjekshus J. , Löyning E.
Published: December 2008

To examine whether renal autoregulation was abolished by vasoconstriction and vasodilatation, experiments were performed on anesthetized dogs with intact renal circulation and nervous supply. Angiotensin or noradrenaline was infused into the renal artery at a constant rate that reduced renal blood flow (RBF) to less than half of control values. By mechanical constriction of the renal artery, perfusion pressure could be reduced to averages of 69 and 80 mm Hg respectively (74 mm Hg during control conditions), before RBF dropped more than 5%. Normal autoregulation was also obtained during intravenous infusion of angiotensin and noradrenaline. during stimulation of renal nerves, and after development of tachyphylaxis to angiotensin. At normal and low arterial pressures, but at similar RBF, noradrenaline or angiotensin was injected into the renal artery. RBF was least reduced at low perfusion pressure, indicating that autoregulation did not compensate for the vasoconstrictive effect of noradrenaline and angiotensin. By acetylcholine infusion. RBF could be doubled, and a curvilinear relationship between RBF and perfusion pressure was obtained. Similar curves could be constructed by the application of Poiseuille's law on the premise that vasoactive agents act mainly on muscle elements other than those participating in autoregulation. It is concluded that autoregulation is essentially independent of nervous and humoral stimuli.
Effect of Oxygen and Umbilical Cord Clamping on Closure of the Ductus Arteriosus in the Guinea‐Pig and the Rat. Studies on Closure of the Ductus Arteriosus. VI
Authors: Hörnblad P. Yngve
Published: December 2008

Full‐term guinea‐pigs were delivered by caesarean section. Living fetuses with intact, or interrupted umbilical circulation were allowed to breathe, for periods of 5 min, air or nitrogen, or air followed by nitrogen. Animals sacrificed immediately on birth served as controls. Sacrifice was performed in liquid nitrogen.–Spontaneously delivered rats were either sacrificed immediately on birth or kept up to 4 hrs at 37° C in air or 8 c/c O2 in N2, before sacrifice in isopentane. cooled by dry ice. In addition, the heart rate of newborn rats, kept at the same temperature and in the same atmospheres, was recorded. – Changes in ductal inner diameter and wall thickness were measured in cryostat sections of both species. Oxygen caused marked constriction of the ductus in the guinea‐pig. Further constriction was found in animals with a clamped umbilical cord. No evidence was obtained of an effect of nitrogen inhalation, neither on the open nor on the constricted ductus. In the rat, reduced atmospheric oxygen concentration caused a delay in ductal closure rate. Lowering of the heart rate was also observed. The present results–obtained in vivo in the guinea‐pig and rat–show that oxygen is essential for closure of the ductus arteriosus, independent of the rate of its closure.
The Mutual Influence of Gastrin and Secretin on the External Pancreatic Secretion in Dogs
Authors: Henriksen F. W. , Worning H.
Published: December 2008

The external pancreatic secretion of fluid, bicarbonate and protein in 4 dogs with Thomas type fistulae, has been studied in response to secretin (1 U/kg b.w.), gastrin (2 U/kg b.w.) and combined secretin–gastrin stimulation. Gastrin exerted a stimulating effect on the pancreatic secretion of fluid, bicarbonate and protein and increased the bicarbonate concentration in the juice significantly above basal level. The combined effect of secretin and gastrin on the secretion of fluid, bicarbonate and protein did not differ from the summarized effect of the two agents given separately. Potentation between secretin and gastrin was not demonstrated.
Colour Specific Features of Visual Cortical Responses in Man Evoked by Monochromatic Flashes
Authors: Cigánek Leodegar , Ingvar David H.
Published: December 2008

In 16 normal human subjects a study was made of averaged responses in the occipital regions to monochromatic flashes of 15 different wavelengths with equal energy. The responses to monochromatic flashes were found to have the same principal components as those previously shown in responses to white light. With low intensity flashes of equal energy, the latencies of all components were shortest in the middle range (514–576 mix), longer in the blue, and longest in the red end of the spectrum. With high intensity stimuli, the latencies were in general shorter, and did not vary with wavelength. The high variability of the amplitudes of the evoked responses made it difficult to correlate amplitude with wavelength. However, some individual curves, as well as the average amplitude/wavelength curve for the whole group of 16 subjects, showed partly significant peaks at 453–475, 551 and at 615 mix, a finding which appears to support the existence of a trichromatic colour receptor mechanism in man. One group of the subjects showed a strikingly stable form of the evoked responses, but varying amplitudes of separate components at different wavelengths. Another group showed very stable forms of the responses which appeared specific to wavelength.
Intercostal and Cerebellar Influences on Efferent Phrenic Activity in the Decerebrate Cat
Authors: Decima Emilio E. , Euler Curt von
Published: December 2008

The intercostal‐to‐phrenic reflex connections, previously studied only in spinal preparations, have now been further analyzed in decerebrate cats and rabbits. The early excitatory part of the response was of the same nature as the corresponcling response component in spinal preparations. The subsequent inhibitory phase was due both to post‐firing depression, as in the spinal state, and to active inhibition. The responses in decerebrate animals showed marked respiratory variations with almost complete abolishment of the excitatory component in the end‐expiratory phase. In the decerebrate preparation the responses from the different portions of the diaphragm showed qualitative differences which disappeared after spinalization. Further signs of differentiated intercostal‐to‐phrenic relations were obtained by stimulating different intercostal nerves. Stimulation of the anterior lobe of cerebellum exerted pronounced effects both on the respiratory phrenic activity–inhibition, sometimes followed by post‐tetanic facilitation–and on the intercostal‐to‐phrenic reflex–removing the inhibition in the end‐expiratory phase. Some of the features of the synaptic organization of the phrenic nucleus are discussed.
Proximal Tubular Reabsorption in the Rat Kidney as Studied by the Occlusion Time and Lissamine Green Transit Time Technique
Authors: Bojesen E. , Leyssac Paul P.
Published: December 2008

Proximal reabsorption rate, determined as the reciprocal of the occlusion time (1/OT), varied in direct proportion to the inulin clearance (Cin) in the range between 1.6 and 0.7 ml/min g KW in nondiuretic rats. Within this range transit time varied from 10 to 24 sec in direct proportion to the occlusion time; the OT/TT ratio averaged 1.10 ± 0.1 (SD). Proximal intra‐tubular pressure averaged 12.4 ± 0.8 mm Hg and did not correlate with Cin

Below inulin clearance of 0.7 ml/min g KW transit time (TT) was further increasing from 24 to 44 sec while the OT remained unchanged, thus the OT/TT ratio was decreasing. Proximal intratubular pressure averaged 11.5 ± 0.3 mm Hg.

Previous estimates of proximal luminal radius from photomicrographs are revised and a more correct value of about 14 μ was found. The length of the proximal segment, as measured in microdissected nephrons, was 10.4 and 10.5 mm in superficial and juxtamedullary nephrons, respectively. Reflux from more distal segments represented an error of no more than 12 % in estimation of proximal reabsorption rate from the measured OT.

The relationship between OT, TT, linear velocity of flow, and tubular fluid/plasma inulin ratio (F/Pin) at 60 % proximal length are derived in quantitative terms. OT/TT = l/ln(F/Pin). From the corrected OT/TT ratio the F/Pin ratio was calculated from values obtained in control rats (“state A”), in rats with partial constriction of the renal artery (“State B”), and in rats with elevated intratubular pressure and urine flow (“State C”).
On the Mechanism of Action for the Effect of Cholecystokinin on the Choledochoduodenal Junction in the Cat
Authors: Hedner Pavo , Rorsman Gunne
Published: December 2008

The resistance of the choledochoduodenal junction was studied by measuring the flow from the common duct into the duodenum under constant infusion pressure and by measuring the intracholedochal pressure under constant infusion rate. It is concluded that the choledochoduodenal junction contains a real sphincter where the normal contracted state depends on an intact cholinergic nerve supply. As the effect of cholecystokinin on the small intestine is mediated by a cholinergic pathway, a similar mechanism of action for its effect on the choledochoduodenal junction was questioned. However, cholinergic and adrenergic mechanisms could be blocked by atropine and reserpine without affecting the antagonism of cholecystokinin to the contraction of the spincter elicited by bradykinin. Thus the effect of cholecystokinin on the choledochoduodenal junction seems to be a direct one and related rather to its effect on the gall‐bladder than to its effect on the small intestine.
Proteolytic Inhibitors in Plasma from Man Treated with a Protease from Aspergillus oryzae
Authors: Jürgens J. , Lindvall S. , Magnuson O. , Orth K.
Published: December 2008

The level of total, heat stable and heat labile inhibitors of a proteolytic enzyme from Aspergillus oryzae‐protease I‐have been studied in plasma from eight patients. After treatment of these patients by infusions of 150 mg of the proteolytic enzyme in 5 % levulose solution, the change in the level of the different inhibitors have been estimated. It has been shown that there is a lowering of the total inhibitors content after each infusion. This decrease is only partly compensated for by the day following the first infusion. After the forthcoming infusions the decrease is completely compensated for resulting in a level before each subsequent infusion which is lower than that before commencement of treatment. This remaning decrease can be attributed to the heat stable inhibitor. A possible mechanism for the thrombolytic effect of the protease is mentioned.
A Method for the Simultaneous Determination of 5‐Hydroxy‐3‐Indole‐Acetic Acid (5‐HIAA) and 5‐Hydroxytryptamine (5‐HT) in Brain Tissue and Cerebrospinal Fluid
Authors: Jonsson John , Lewander Tommy
Published: December 2008

A method is described for the isolation of 5‐HIAA in brain tissue extracts or cerebrospinal fluid by use of a Sephadex G‐10 column. The eluate is taken for fluorimetric determination of 5‐HIAA in 3 M hydrochloric acid. Tissue blanks are obtained by destruction of 5‐HIAA with potassium ferricyanide plus UV irradiation or with hydrogen peroxide. Recovery of 5‐HI.4A from brain extracts was above 90 %. The sensitivity of the method allows quantitative determination of about 50 ng of 5‐HIAA in a tissue extract. 5‐HT in the effluent and washings from the Sephadex G‐10 column was isolated on a weak cation exchange resin and determined fluorimetrically (AndCn and Magnusson 1967). Recovery of 5‐HT added to brain extracts was 85 %. Determination of 5‐HIAA in 3–5 ml samples of human cerebrospinal fluid could be performed with the present method with a recovery of 83 %.
Species Distribution of Sympathetic Cholinergic Vasodilator Nerves in Skeletal Muscle
Authors: Bolme Per , Novotný Jozef , Uvnäs Börje , Wright Peter G.
Published: December 2008

The lumbar sympathetic chain was electrically stimulated in different species before and after blocking the adrenergic vasoconstrictor nervous response. Blood flow in the hind limb skeletal muscles was measured. In all species studied, fox, sheep, goat, monkey (five different strains), polecat, rat, badger, opossum rat and hare, stimulation of the lumbar chain before adrenergic blockade resulted in a vasoconstriction. After blocking the vasoconstrictor nervous response stimulation elicited a blood flow increase in fox, sheep and goat. After atropine, the response to stimulation was blocked, indicating that sympathetic cholinergic nerves had been activated. In the other species studied no vasodilator response was observed upon sympathetic chain stimulation. The results suggest that the role attributed to the vasodilator nerves, anticipatory to muscle exercise, are played by other mechanisms in species lacking sympathetic cholinergic vasodilator nerves.
A Comparison of Blood Viscosity Measured In Vitro and in a Vascular Bed
Authors: Djojosugito A. M. , Folkow B. , ÖBerg B. , White S.
Published: December 2008

Blood viscosity in vivo (“apparent viscosity”) and its variations with flow rate was analyzed in the maximally dilated calf muscle vascular bed of the cat by comparing pressure‐flow relationships for blood and a Newtonian fluid (dextran‐Tyrode) over a flow range between 60 and 0.2 ml/min × 100 g tissue. Viscosity in vitro for the same perfusates was measured in a cone‐plate viscometer.—Apparent viscosity was much lower (approximately 50 %) than in vitro values at high shear rates, with less variation between animals. It increased with decreased flow but was as a maximum only doubled, which occurred at flows around 0.5 ml/min × 100 g. Since such small flows normally occur in constricted vessels with higher flow velocities than at maximal dilatation, the range of viscosity changes with flow in the intact circulation is probably decidedly smaller. The steep rise of viscosity in vitro at quite low shear rates had no counterpart in vivo; in fact, viscosity then tended to fall again. The discrepancies between blood viscosity in vivo and in vitro seem to be related to vascular dimensions, favouring “bolus flow” and hence low regional viscosity in the most narrow vessels, which may become more pronounced at further luminal reduction, active or passive.

Addition of high molecular weight dextran (HMD) raised apparent viscosity to seemingly high levels at low flows. However, to a considerable extent this appears to be due to cell aggregation and plugging of microvessels rather than to a genuine increase of blood viscosity.
The In Vivo CO2 Buffer Capacity of Rat Brain Tissue under Carbonic Anhydrase Inhibition
Authors: Kjällquist A. , Messeter K. , Siesjö B. K.
Published: December 2008

The effect of acetazolamide upon the in vivo CO2 buffer capacity of rat brain tissue was investigated by injecting the animals with the drug in two doses of 50 mg/kg each before they were anesthetized and subsequently exposed to various CO2 tensions for 40–60 min. Acetazolamide was found to give a marked lowering of the CO2 buffer capacity. Thus, the intracellular buffer capacity, calculated as β=Δlog pCO2/ΔpHi, was found to be about 1.4, and thus considerably lower than the intracellular CO2 buffer capacity of animals not given acetazolamide but otherwise treated in an identical way (β= 2.3, see Kjällquist, Nardini and Siesjö 1969 a). The results indicate that acetazolamide interferes with an active transport of hydrogen ions between cells and the extracellular fluids which is dependent on carbonic anhydrase.
The Catechol Amine Content of the Bull Retractor Penis Muscle
Authors: Klinge Erik
Published: December 2008

The noradrenaline, adrenaline and dopamine content of the bull retractor penis muscle was determined. Dowex 50‐X4 ion exchange columns were used for the purification procedure and for the separation of dopamine from the other catechol amines. The muscle contains con siderable amounts of noradrenaline but it probably is devoid of adrenaline. The dopamine content is about 10 % of that of noradrenaline. It seems possible that the impulses main taining the almost continuous contraction of the bull retractor penis muscle are conducted along sympathetic nerves.
On the Mechanism of Depletion of Noradrenaline Stores by Iso‐Monomethylnicotinium Bromide
Authors: Hedqvist P.
Published: December 2008

The quaternary nicotine analogue iso‐monomethylnicotinium bromide (IMN) inhibits the uptake of noradrenaline (NA) in the perfused guinea‐pig heart without causing any change in the distribution between the particulate and soluble fractions of the NA taken up. In the isolated perfused cat spleen IMN increases the resting outflow of NA, and the NA overflow response to nerve stimulation, while that to tyramine (TA) is reduced. IMN does not affect release or uptake of NA in isolated splenic nerve granules, or the formation of NA from tyrosine in this system.

It is suggested that IMN causes depletion of NA stores both by releasing NA, probably from extragranular sites, and by inhibiting reuptake of the NA released.