bluuebunny/crossref_metadata_2025 huggingface dataset:
Unidirectional Fluxes in Isolated Splenic Nerve Vesicles Measured by a Millipore Filter Technique:
Authors: Klein Richard L. , Lagercrantz Hugo
Published: December 2008

Isotopically labelled noradrenaline (NA) exchange was determined in an improved preparation of NA storage vesicles isolated from bovine splenic nerve trunk. A Millipore filter technique was used which permitted analyses of unidirectional fluxes. In a Mg‐ATP supplemented medium at 30 and 20° C, vesicle NA is completely exchangeable with 0.5 to 3.0 μg l‐NA/ml in the medium. The kinetics are compatible with a single exponential component of exchange, and the data suggest a fully saturated Mg‐ATP complexing under these conditions.

Reserpine in a concentration range between 2 × 10‐8 and 2 × 10‐7 M causes more pronounced inhibition of the transfer coefficient for NA influx than for efflux. However, no net loss of vesicle NA occurs because the drug inactivates a proportional amount of the readily exchangeable NA pool. Within the concentration ranges of NA and reserpine tested, virtually complete inhibition of NA exchange can be achieved and reversal of this inhibition by elevating the NA concentration in the medium can be demonstrated. The data is consistent with the suggestion that reserpine acts via transport sites in the vesicle membrane, rather than on the intravesicular NA complex per se.

This membrane stabilizing concentration range of reserpine causes no obvious deleterious effects on the vesicles at the electron microscopic level.
Efferent Impulses in the Chorda Tympani Nerve of the Rat
Authors: Hellekant Göran
Published: December 2008

Efferent impulses in the chorda tympani nerve of the rat could be recorded under neuroleptic analgesia but not under barbiturate anesthesia. The number of impulses recorded from the whole nerve ranged from 10 to about 120 imp/s. Recordings from branches of the combined chorda‐lingual nerve suggest that most of the observed activity was directed to structures inside the tongue.
The Disappearance of Acetylsalicylic Acid (ASA) in Aqueous Solution from the Cat Stomach and its Influence on the Transmucosal Ion Transport in the Innervated Non‐secreting Stomach
Authors: Frenning Bertil
Published: December 2008

During instillation of aqueous solutions of acetylsalicylic acid (ASA) into innervated, non‐secreting whole stomach pouches in the cat, parallel decreases in the salicylate and hydrogen ion concentrations took place. There was a decrease in volume by an average of 20–25%. Secretion did not affect the absorption of ASA. To study the effect of ASA in aqueous solution on the ionic permeability of the gastric mucosa, HC1 was instilled before and repeatedly after an instillation of ASA. The gastric mucosal permeability for ions was increased after an instillation of ASA. A study of the changes in electrolyte concentration in the instilled HC1 solutions showed that a significant effect on the decreases in hydrogen and chloride ion concentration persisted 90 and 60 min respectively after an ASA instillation. The net effluxes of hydrogen and chloride ions and the net influx of sodium ions were, however, significantly increased only during 30 min. After an instillation of ASA a 2‐fold increase in the pepsin output was obtained during instillations of HC1. In no case was hemorrhage observed during instillation of ASA, and only in 1 expt. during the immediately following instillation of HC1. In all but 1 expts. hemorrhages occurred during the subsequent HC1 instillations. It is suggested that the permeability‐increasing effect of ASA is due to loosening of the mucosa with a consequent increase of the extracellular space.
Effects of Pilocarpine on L‐Dopa Turnover in the Exocrine Rat Pancreas
Authors: Alm P.
Published: December 2008

The turnover of L‐DOPA was microscopically and chemically studied in rats after pretreatment with pilocarpine alone or in combination with nialamide. Whenever pilocarpine was given, there was an almost complete extrusion of fluorescent (i.e.dopamine containing) zymogen granules from the exocrine cells. In such cases, specific fluorescence frequently appeared in the acinar duct lumina and the secretory duct system. Compared with animals given L‐DOPA, pretreatment with pilocarpine resulted in higher initial concentrations of DOPA but unchanged levels of DA. These were then eliminated faster than in non‐pilocarpine pretreated animals. In animals pretreated with pilocarpine and nialamide the DA elimination was faster than in animals pretreated with only pilocarpine. The result of the present work indicate that the L‐DOPA turnover is influenced by changes in the pancreatic secretory activity.
Studies on Tetrodotoxin Resistant Action Potentials in Denervated Skeletal Muscle
Authors: Harris J. B. , Thesleff S.
Published: December 2008

In this study it is shown that action potential generation in rat, mouse and cat muscles is blocked by tetrodotoxin (TTX, 10‐6M) but that the chronically denervated muscles of these species are partially resistant to TTX. In denervated rat muscles the development of the TTX resistant action potential during the first four days of denervation is paralleled by the spread of extrajunctional cholinergic sensitivity. However, the extrajunctional cholinergic receptor and the TTX resistant action potential can be selectively blocked by drugs, indicating that the action potential site and the cholinergic receptor are not identical structures. Denervated muscles are also partially resistant to saxitoxin, although less so than to TTX.
A Standardized Technique for Drainage and Collection of Cardiac Lymph
Authors: Kluge Trond , Ullal Shiv R.
Published: December 2008

A standardized method for cannulation of cardiac lymphatics and drainage of cardiac lymph in dogs is presented. The technique comprises visualization of lymph vessels by myocardial injection of T 1824 dye and cannulation of an afferent lymphatic to the cardiac lymph node. A stable drainage is ensured by traction and countertraction on sutures adjacent to the cannula. Sucessful collection of lymph has been obtained in about 85 per cent of the experiments, and for periods lasting more than 6 h. The method may prove a useful tool for further investigations in cardiac physiology.
The Action of Progesterone on the Sodium Transport of Isolated Frog Skin
Authors: Tomlinson R. W. S.
Published: December 2008

It has been shown that progesterone at concentrations greater than 10‐5 M in the medium bathing the outside surface of the isolated frog skin causes an inhibition of the short‐circuit current within a few minutes. The inhibition is due to a decreased influx of sodium with no effect on sodium efflux or chloride influx. The inhibition is readily elicited when the progesterone is added to the outside bathing medium as opposed to the inside bathing medium although progresterone transfer across the skin is the same in both directions. The adenosine triphosphate concentration of the progesterone treated skins was not significantly different from the controls. It is suggested that progesterone interacts with the lipid moeity of an outward‐facing membrane preventing sodium influx.
Interaction between the Fastigial Pressor Response and the Baroreceptor Reflex
Authors: Lisander Björn , Martner Jan
Published: December 2008

Experiments were performed on chloralosed cats with recording of blood pressure, heart rate and regional blood flows. The response pattern elicited by stimulation of the cerebellar fastigial nuclei, was closely similar to that caused by carotid baroreceptor unloading. Thus, the cardio‐acceleration caused by fastigial stimulation was due not only to increased accelerans tone, as has been suggested, but also to withdrawal of vagal inhibitory activity. However, electrolytic destruction of the fastigial “pressor area” did not alter the reflex cardiovascular responses to carotid baroreceptor unloading or to somatic pressor afferent stimulation, indicating that this area did not exert any tonic influence on the centres conveying such reflexes. Evidence is presented for a differentiated interaction between the baroreceptor inhibitory reflex and the fastigial excitatory response with a relatively stronger fastigial suppression of the reflex action on the heart than on the vascular bed. This differentiation involves an element of central suppression of the reflex cardiac control, though it is partly a consequence of the different neuroeffector characteristics of heart and vessels.
The Effect of Stomach Distension on the Efferent Activity in the Chorda Tympani Nerve of the Rat
Authors: Hellekant Goran
Published: December 2008

The efferent activity in the chorda tympani nerve of the rat was recorded under neuroleptic analgesia. The results show that this activity decreased when the stomach was distended. The effects caused originated from the stomach and diminished after cutting the vagal nerves. It is suggested that the efferent activity of the chorda tympani nerve can be influenced by hunger and satiety.
Pulmonary Blood Volume and “Pulmonary Hematocrit” during Hypervolemia in Rats
Authors: Aarseth P.
Published: December 2008

In rats erythrocytes and plasma albumin were labelled by radioisotopes, and circulatory arrest was then achieved by rapidly freezing the intact animal in liquid nitrogen. Pre‐mortal blood content in different organs could then be evaluated by measuring the radioactivity in tissue samples from the frozen animals. In one group of rats the circulating blood volume was increased 10 % by blood transfusions. The pulmonary blood volume in these hypervolemic animals was found to increase by 80%. Most of this increase was due to an augmentation of the pulmonary plasma content, consequently “pulmonary hematocrit” had decreased markedly. It could be demonstrated that this increase in pulmonary blood volume was caused by the hypervolemia per se, and not by substances released from or by the transfused blood. When the left thoracic vago‐sympathetic nerve trunk had been cut beforehand, no increase in lung blood volume was found in hypervolemic rats. It is suggested that the increase in lung blood volume normally found after a blood transfusion, could stem from a constriction of small vessels. This could then lead to a passive distension of vascular sections upstreams to the constricted ones.
Perfusate Qualities and Spontaneous Edema Formation in an Isolated Perfused Lung Preparation
Authors: Nicolaysen G.
Published: December 2008

In isolated perfused lung preparations spontaneous edema tends to develop with time of perfusion. Such edema is probably in most cases due to a gradual increase in capillary permeability. In the present work some aspects of the relationship between perfusate qualities on the one hand and spontaneous development of edema on the other have been investigated in an isolated, ventilated and perfused rabbit lung preparation. Perfusion with plasma at 38° C preserved the preparations for a variable length of time. In some cases edema developed within 2 h, in other preparations, however, definite edema did not develop within 6 h of perfusion. With plasma as perfusate at 28° C there were invariably no signs of edema in the course of a 6 h perfusion period. When 4% (w/v) albumin in a Krebs Ringer solution was used as a perfusate at 38° C, massive edema was always formed within 2 h of perfusion. This development was somewhat retarded when the same perfusate was used at 28° C. In confirmation of previous findings the presence of erythrocytes in the perfusate was found to prolong the survival time of the preparations. The time interval prior to edema formation was thus significantly increased when erythrocytes were added to the perfusate of 4% albumin in Krebs Ringer solution. The effect was more marked with an hematocrit of 30–40 % than with one of 10–11 %. The results indicate that the maintenance of normal capillary permeability is dependent upon some form of biochemical interplay between the perfusate and the capillary endothelium.
Release of Monoamines Evoked by Field Stimulation– Studies on Some Ionic and Metabolic Requirements
Authors: Farnebo Lars‐Ove
Published: December 2008

Electrical field stimulation of isolated tissues can cause release of3H‐monoamines previously taken up into monoamine nerve terminals. The stimulation‐induced overflow of tritium was investigated in isolated irides previously incubated with3H‐noradrenaline, cerebral cortex slices incubated with3H‐noradrenaline or3H‐5‐hydroxytryptamine and neostriatal slices incubated with3H‐dopamine. No stimulation‐induced tritium overflow was obtained if Ca++was excluded from the buffer or tetrodotoxin was added to the buffer. Mg++20 mM completely inhibited the stimulation‐induced overflow from isolated rat iris. Exclusion of K+slightly increased the stimulation‐induced overflow. At K+20 mM no stimulation‐induced overflow was obtained. K+50 mM evoked a great increase of the tritium overflow. Low Na+concentrations reduced the stimulation‐induced overflow. In agreement with previous investigations it is concluded that the present stimulation technique may cause relase of monoamines via action potentials propagated along the nerves.

Inhibition of oxidative phosphorylation moderately increased the stimulation‐induced overflow from the rat iris. This is probably due to partial inhibition of noradrenaline reuptake into the nerve terminals. Exclusion of glucose from the buffer greatly increased both the spontaneous and the stimulation‐induced tritium overflow. The stimulation‐induced overflow in the absence of glucose was only partially Ca++‐dependent. It is concluded that the release process for noradrenaline is not immediately inhibited after interference with energy‐yielding processes.
Reflex Inhibition of Sympathetic Nerve Activity by Phenoxybenzamine
Authors: Aars Harald
Published: December 2008

The effects on baroreceptor and sympathetic nerve activity of the a‐adrenergic blocking agent phenoxybemamirie have been investigated in 13 anesthetized rabbits. Nerve activities were recorded at various blood pressure levels, obtained by stepwise changes of blood volume. With phenoxybenzamine, aortic nerve activity at 80 and 90 mm Hg exceeded control values by 66 and 62 %. At the same pressures, renal nerve activity was reduced by 30 and 55 %. Although blood pressure started to fall shortly after injecting the drug, about 20 min elapsed before development of maximum effects on the nerves. When studied during stepwise changes of blood pressure after a similar period of hypotension—but without the drug‐sympathetic nerve activity had increased. Phenoxybenzamine had accordingly effected a suppression of sympathetic activity, suggesting that the hypotensive response to phenoxybenzamine is aided by increased reflex inhibition of sympathetic nerve activity.
Kininogenase Activity in the Stimulated Submandibular Salivary Gland in Cats
Authors: Gautvik K. M. , Nustad K. , Vystyd J.
Published: December 2008

The influence of prolonged stimulation of the chordo‐lingual nerve (1 1/2–2 h) on secretion, blood flow and the content of kininogenase in cat submandibular glands has been studied. Quantitative estimation of hydrolysis of α‐N‐Benzoyl‐L‐Arginine Ethyl Ester (BAEE) at pH 8.5 was found to be a useful measure of total kininogenase activity. The volume of secreted saliva decreased throughout the period of chorda stimulation by as much as 30 per cent, while the salivary concentration of kininogenase was reduced by up to 80 per cent. The maximal increase in venous outflow as well as the duration of the chorda‐induced vasodilatation was also considerably reduced throughout the expermenrs. The kininogenase activity in the glands themselves was reduced by 20–40 per cent. Stimulation of the chorda caused a 15–80 per cent reduction of the kininogenase activity also in cats which had received atropine so that secretion of saliva was blocked. During activation of the submandibular gland a major part of the reduction in kininogenase activity may be explained by release of enzyme into saliva. However, since a substantial reduction in kininogenase activity was also found in activated, atropinized, non‐secreting glands, some enzyme appears to be released to the interstitial fluid, whereby kinin formation may take place.
Vasoconstrictor Fibre Discharge to Skeletal Muscle, Kidney, Intestine and Skin at Varying Levels of Arterial Baroreceptor Activity in the Cat
Authors: Kendrick Ed , ÖBerc Benot , Wennergren Göran
Published: December 2008

Estimations of the average discharge rates in vasoconstrictor fibres to skeletal muscle, kidney, intestine and skin at varying levels of arterial baroreceptor activity were made by comparing quantitatively the reflexly induced vascular responses with those obtained with stimulations of the regional vasoconstrictor fibres at known frequencies. The results indicate that withdrawal of baroreceptor restraint was normally followed by a considerably lower firing rate in renal vasoconstrictor fibres than in e.g. skeletal muscle vasoconstrictor fibres. A complete elimination of the inhibitory influence induced vasoconstrictor fibre discharge rates up to 8 imp/s in skeletal muscle but only at most 4 imp/s in the kidney. Intestinal vasomotor fibres were found to be activated to approximately the same extent as those to skeletal muscle. The vasomotor fibres to the cutaneous arterio‐venous anastomoses were evidently not activated when the baroreceptors were unloaded. The reason for this non‐uniform activation of the different sets of vasoconstrictor fibres seems to be different levels of spontaneous activity in the respective “neuron pools” in the bulbar vasomotor centre. The renal vascular responses to baroreceptor unloading became augmented when the excitatory level in the vasomotor centre was enhanced, as e.g. when the animal became acidotic.
Effects of 2, ‐4 Dinitrophenol on Release and Uptake of Noradrenaline in Guinea Pig Heart
Authors: Chang P. , von Euler U. S. , Lishajko F.
Published: December 2008

Dinitrophenol (DNP) was shown to have cardiac stimulant action on the isolated perfused guinea pig heart. The initial large increase in the force of contraction of the heart was followed by a smaller response which persisted throughout the DNP perfusion. On washout the activity of the heart returned to its previous level. Further DNP perfusion had no effect on the heart even though its amine level was not depleted. However, the positive inotropic effect of DNP reappeared in the heart after perfusion with noradrenaline (NA). Propranolol blocked the cardiac response to DNP. The metabolic uncoupler reduced the NA content in the heart and raised the amine level in the perfusate. The uptake of exogenous NA, and of 14C‐NA, by the heart was not affected by low and high concentrations of DNP. The results suggest that DNP may have a direct action releasing NA from an extragranular pool.
Effects on the Pulmonary Circulation of Suddenly Induced Intravascular Aggregation of Blood Platelets
Authors: Bø G. , Hognestad J.
Published: December 2008

When intravascular platelet aggregation was induced by intravenous infusion of collagen extract, a temporary and marked increase in pulmonary vascular resistance (PVR) was observed. The number of circulating platelets was gradually reduced after the first few infusions of collagen. After 4–6 infusions of collagen the vascular response vanished, and the platelet count in arterial blood remained fairly stable. When a vasodilator was infused simultaneously with the collagen, the pressure response could be abolished. Histological examinations of lungs at the peak of a pressor response to collagen revealed aggregated platelets in small arterial vessels and capillaries. After many infusions larger vessels were found occluded by aggregated platelets. It is concluded that platelet aggregation in the blood arriving in the lung creates a strong vasoconstriction in the pulmonary vascular bed. This response is related to release of material from the platelets.
Effects of Chlorpromazine, Imipramine, and Quinidine on the Mechanical Activity of Single Skeletal Muscle Fibres of the Frog
Authors: Andersson K.‐E.
Published: December 2008

Chlorpromazine (8×10‐6–3×10‐5M), imipramine, and quinidine (5×10‐5–10‐4M) prolonged the relaxation phase of potassium induced contractures in single skeletal muscle fibres of the frog without affecting the maximum tension amplitude. These drugs also shifted the curve, which relates peak contracture tension to external potassium concentration, to lower potassium values and lowered the mechanical threshold. This is in contrast to other membrane stabilizers such as tetracaine, cocaine, and procaine, which have been reported to shift the curve to higher potassium values and to increase the mechanical threshold. In high concentrations, chlorpromazine (10‐‐4M), imipramine, and quinidine (> 10‐‐3M) produced slowly developing and only partially reversible contractures. Similar contractures could be evoked in fibres that were depolarized in isotonic potassium methyl sulphate solution and in fibres that had been soaked for 10–30 min in a calcium‐free medium. The results support the idea that the contractile effects produced by chlorpromazine, imipramine, and quinidine are mediated by action upon intracellular calcium storing structures.
The Sodium Transport Pool in Frog Skin under Open‐ and Short‐circuit Conditions
Authors: Lyttkens Leif
Published: December 2008

The sodium pool of frog skin was studied by a method of continuous direct analysis under open‐ and short‐circuit conditions. No change in the transport pool on short‐circuiting was found. The results are discussed on the basis of proposed models for the sodium transport in frog skin.
The Role of Muscle Stiffness in Meeting the Changing Postural and Locomotor Requirements for Force Development by the Ankle Extensors
Authors: Grillner S.
Published: December 2008

The relationship between the length and stiffness (force/length change) of active muscle and the rates at which motor units are activated by distributed stimulation of divided ventral rootlets supplying the muscle has been explored in cat soleus and lateral gastrocnemius. At stimulus rates equivalent to those used in locomotion (15—55 p/s) peak muscle stiffness is at muscle lengths also used in locomotion. At lower rates of stimulation equivalent to those developed in the tonic stretch reflex of the decerebrate cat, peak muscle stiffness occurs at larger muscle lengths but these lengths are within the range of those used for investigation of the reflex. These experimental results were then compared to the sets of theoretically derived results concerning: a) the amount of force needed from the ankle extensors to counteract a load applied to the hindlimb along a vertical axis when ankle and metatarsophalangeal angles are changed relative to the mechanical axis; and b) the amount of force developed by ankle extensors during slow walking. In all cases (theoretical and experimental) the results reveal a close correlation between required force, muscle length and muscle stiffness. The time lag between a change in motor unit discharge and tension development was also calculated to reveal that in many situations (notably gallop) only muscle stiffness can provide a load compensation, whereas the delays are too long to allow a reflexly induced load compensation.
Pre‐ and Postganglionic Secretory Pathways for the Parotid Gland of the Dog
Authors: Holmberg Jan
Published: December 2008

Recently earlier unknown secretory nerve fibres to the parotid of the dog have been traced outside the auriculo‐temporal nerve, on the internal maxillary artery and in the facial nerve. In the present experiments it was investigated whether they conveyed impulses from the “classical” preganglionic nerve, the tympani one, or from secretory nerves outside this nerve, the existence of which has been suggested by previous workers. The parotid secretory response to electrical stimulation of the tympanic nerve was found to be successively reduced when the auriculo‐temporal nerve, the internal maxillary artery and the facial nerve were divided. Some additional evidence is presented for the conception, that most of the impulses travel in the tympanic nerve and are conveyed to the gland via the auriculo‐temporal nerve and the adventitia of the internal maxillary artery. Uncharted secretory pathways outside the tympanic nerve were found to contribute very little to the reflexly induced secretory response, because after division of the tympanic nerve this response was abolished in 5 glands out of 10, whereas only a slight secretion was obtained in the others.
Manoeuvres Affecting Sympathetic Outflow in Human Muscle Nerves
Authors: Delius W. , Hagbarth K.‐E. , Hongell A. , Wallin B. G.
Published: December 2008

Multi‐unit sympathetic activity was recorded in human muscle nerves, together with measurements of intra‐arterial blood pressure and forearm or calf blood flow, during manoeuvres causing circulatory adjustments. Manoeuvres causing an increased vascular resistance in the forearm or calf were regularly associated with an increase in sympathetic outflow, proving that the neural activity was dominated by vasoconstrictor impulses. The inverse changes of blood pressure and sympathetic activity observed during Valsalva's manoeuvre and mental stress are explicable in terms of baroreflex control of the neural outflow. However, during muscle work and hyperventilation the relation between blood pressure and sympathetic activity was more complex, indicating that the baroreflex influence was superimposed or modified by other regulatory mechanisms. Some manoeuvres known to affect sympathetic outflow in skin nerves caused no appreciable change in sympathetic muscle nerve activity.
Convergence in the Reciprocal la Inhibitory Pathway of Excitation from Descending Pathways and Inhibition from Motor Axon Collaterals
Authors: Hultborn H. , Udo M.
Published: December 2008

With intracellular recording from motoneurones and utilizing the technique of spatial facilitation it has been investigated if those la inhibitory interneurones which receive excitation from supraspinal centres also can be inhibited from recurrent motor axon collaterals. For each motoneurone the stimulation strengths were chosen so that separate stimulation of either the supraspinal system or la afferents did not evoke any 1PSP while a combined stimulation at suitable intervals gave a large IPSP. When preceded by stimulation of ventral roots this test IPSP was abolished or decreased. This was found in about 100 motoneurones belonging to different hindlimb muscles in which an IPSP appeared after facilitation from vestibulo‐, rubro‐or cortico‐spinal tracts.

It is thus concluded that a convergence of supraspinal excitation and recurrent inhibition occurs on the same la inhibitory interneurones.
The Motility of the Pancreatic Duct of the Cat; an in‐vitro Study
Authors: Lenninger Svex
Published: December 2008

Segments of the pancreatic duct of cats were suspended in Krebs solution and connected to a force‐displacement transducer. Spontaneous, rhythmic contractions were recorded from all parts of the duct. The contractions seem to be exerted by longitudinally orientated muscle cells and are probably myogenic. Acetylcholine, bradykinin and histamine increased the tension. Noradrenaline caused a slight increase in tone while isoprenaline relaxed the duct. The spontaneous activity was annulled when bile was present in the bath.
Subcellular Localization of the Prostaglandin System in the Rabbit Renal Papilla
Authors: ÄNggård E. , Bohman S. O. , III J. E. Griffin , Larsson C. , Maunsbach A. B.
Published: December 2008

The occurrence of prostaglandins (PG), prostaglandin precursor acids, prostaglandin synthetase and 15‐hydroxy prostaglandin dehydrogenase was studied in subcellular fractions isolated from homogenates of rabbit renal papilla by sucrose density gradient centrifugation. The investigated fractions were lipid droplets, supernatant, microsomes and mitochondria as verified by electron microscopy. Most of the prostaglandins was found to be prostaglandin E2 and was present in the supernatant whereas the prostaglandin synthetase occurred most abundantly in the microsomal fraction.‐Nearly all of the recovered prostaglandins were formed during the preparation of the subcellular fractions. Arachidonic acid was the major esterified C20 acid and had the highest relative concentrations in the supernatant, microsomes, and mitochondria, whereas the lipid droplets had lower concentrations. No detectable 15‐hydroxy prostaglandin dehydrogenase was present in the supernatant fraction of the papilla. The results indicate that in the rabbit renal papilla prostaglandin E2 is formed mainly from locally available arachidonate in membranes which sediment in the microsomal fraction and which may be derived from either cell membranes or membranes of the endoplasmic reticulum. After their formation the prostaglandins are probably released into the cytoplasm of the cells rather than being concentrated within specific subcellular particles and may leave the papilla without undergoing metabolic inactivation.
Microdetermination of Free Amino Acids in Pancreatic Islets Isolated from Obese‐Hyperglycemic Mice
Authors: Briel Günter , Gylfe Erik , Hellman Bo , Neuhoff Volker
Published: December 2008

Free amino acids were measured with a microtechnique employing labelling with 14C‐dansyl‐Cl and separation with two‐dimensional thin‐layer chromatography. Most amino acids occurred in greater amounts in the islets than in the exocrine pancreas. Aspartic acid, valine and leucine were present in tenfold amounts. It is postulated that the β‐cells are equipped with binding sites for large amounts of the latter amino acid. Like nervous tissue, the pancreatic islets were characterized by the presence of gamma‐aminobutyric acid and high levels of taurine.
Method for Studying Qualitative and Quantitative Changes of Blood Flow in Skeletal Muscle
Authors: ‐IngvarBranemark Per , Eriksson Elof
Published: December 2008

Branemark, P.‐I. and E. Eriksson. Method for studying qualitative and quantitative changes of blood flow in skeletal muscle. Acta physiol. scand. 1972. 84. 284–288.

A vital microscopic method for studying changes of blood flow in skeletal muscle has been devised. The tenuissimus muscle of cat and rabbit was dissected and arranged for direct microscopic observation. Simultaneous measurements were made of central blood pressure, pulse, pulse pressure and regional blood flow as well as of the diameters and flow rates of the vessels with a diameter of 2 μ–100 μ. Hematological phenomena and changes in blood cell rheology could also be registered. This method will be used for studying the function of the resistance vessels and the effects on the microcirculation of hemorrhagic shock.
Light Sensitivity of the Compound Eye of a Moth (Manduca Sexta) Reared on a Retinol Deficient Diet
Authors: Boëthius Jörgen , Carlson StanleyD. , Hoglund Gunnar , Struwe Goran
Published: December 2008

Boëthius, J., S. D. Carlson, G. Hoglundand G. Struwe. Light sensitivity of the compound eye of a moth (Manduca sexta) reared on a retinol deficient diet. Acta physiol. scand. 1972. 84. 289–294.

The photoreceptor response was recorded in the compound eye of a moth (Manduca sexta) reared on a retinol (vitamin‐'A) deficient diet. The configuration, amplitude and spectral sensitivity of the receptor potential was similar to that found for normal eyes. The retinol deficient eyes are structurally deranged. The present results therefore indicate that structurally deranged photoreceptors response generate normal receptor potentials.
Circulatory Control via Vagal Afferents
Authors: Castenfors Jan , Sjöstrand Torgny
Published: December 2008

Castenfors, J. and T. Sjöstrand. Cirulatory control via vagal afferents. I. Adjustment of heart rate to variations of blood volume in the rat. Acta physiol. scand. 1972. 84. 347–354.

On withdrawal of 20–35 % of the blood volume the heart rate may increase, decrease or remain unchanged. The effect has been found to be dependent on animal strain, anesthesia and the autonomic balance. In Sprague‐Daley rats a lowering of the heart rate has been practically constantly observed, sometimes after an initial rise. Bilateral vagotomy eliminates the reduction of heart rate but does not obviously influence the rise. Atropine inhibits the bradycardia largely, and propranolol the tachycardia. On administration of both atropine and propranolol, both the lowering and the rise of heart rate are entirely eliminated. Ligation of the common, external and internal carotid arteries eliminates the bradycardia. Bilateral exclusion of afferents via the communicating branch between the superior and inferior laryngeal nerves usually eliminates the bradycardia.

It is presumed that in the rat the heart rate response to hemorrhage is determined by antagonistically acting receptor mechanisms which affect the autonomic tone on the heart, one in a vagotonic and the other in a sympathicotonic direction. The afferents mediating the bradycardia run entirely or for the most part via the recurrent nerve and the laryngeal com‐municans to the cranial part of the cervical vagus.
Gas Permeability of the Alveolo‐pleural Wall in the Mouse Lung
Authors: Andersen Birgit , Madsen Joop
Published: December 2008

Andersen, B. and J. Madsen. Gas permeability of the alveolo‐pleural wall in the mouse lung. Acta physiol. scand. 1972. 84. 382–395.

Transpulmonary pressure was recorded in isolated mouse lungs during and after step increases in volume. The concomitant sudden increase in transpulmonary pressure was immediately followed by a sharp pressure fall, indicative of stress relaxation. This fall passed into a less pronounced, continuing decline, which appeared to decrease monoexponentially with time. Time constants for this monoexponential pressure fall scattered between 0.005 and 0.017 min˜2 with a tendency to highest values in small animals. In similar experiments, where the lungs were filled and surrounded with N2, time constants were found of the same order of magnitude. In these experiments diffusion capacities for N2 between 0.1 and 0.2 μ min‐1 cm H2O_1 were found. The volumes of gas disappearing from the lungs per unit time and pressure were slightly larger, when the experiments were conducted in air than when done in N2. This difference is probably due mainly to oxygen consumption by surviving lung tissue. Xe passed the alveolo‐pleural wall at a rate 3 times that of N2, while O2 passed the wall at a rate twice that of N2. These figures are consistent with gas diffusion through the intact lung wall.
Effect of Cooling on Synaptic Transmission through the Cuneate Nucleus
Authors: Andersen P. , Gjerstad L. , Pasztor E.
Published: December 2008

The synaptic transmission through the cuneate nucleus was studied during local cooling of the dorsal column region. Field potentials, recorded from the surface as well as inside the nucleus, were greatly increased during moderate cooling (to 30–25o C) but diminished rapidly if the cuneate temperature fell below about 20o C. The increase was most evident for the afferent fibre volley potentials, but large changes of synaptic potentials (N‐wave) were regularly seen as well. The increase (up to several hundred per cent) was partly rate‐dependent since fast cooling gave larger increases than slower cooling did. In spite of the greatly increased N‐wave, the transmission through the nucleus was always reduced. This was tested in various ways: measurement of the latency and probability of firing of single units, “killed end”–recording from lemniscal fibres as a measure of number of discharging cuneate neurones, and measurement of the size of thalamic and cortical field potential produced by impulses relayed through the cuneate nucleus. The reduced transmission was most likely due to a greatly increased synaptic delay, with slowing of conduction along the terminal branches of the afferent fibres as a contributing factor. On severe cooling blocking of conduction in these branches occurred. During moderate cooling the probability of firing of most relay cells remained strikingly high.
Effects of Cooling on Inhibitory Processes in the Cuneate Nucleus
Authors: Andersen Per , Gjerstad Leif , Pasztor Emil
Published: December 2008

Inhibitory mechanisms in the dorsal column nuclei have been studied during local cooling. The inhibition of transmission of a cutaneous volley across the cuneate nucleus caused by a preceding volley to the same or a neighbouring cutaneous nerve was prolonged and slightly increased by a moderate (25–30o C) reduction of the cuneate temperature. The excitability of presynaptic fibres and of the postsynaptic cell membrane both decreased progressively with decreasing temperature. Presynaptic depolarization increased during moderate cooling (25–30o C) but disappeared when the temperature was reduced to about 20o C.

One type of interneurone in the cuneate nucleus showed a progressive disruption of the normal pattern of firing with a gradual increase in the initial latency. An other type showed an increase of the rate and duration of the discharges to a single afferent volley on cooling. The latter type was susceptible to stimulation at 10 per s or higher. The behaviour of the latter interneurones matched the increased and prolonged presynaptic depolarization. These cells may be interneurones in a presynaptic inhibitory pathway. The prolonged and moderately increased inhibition caused by local cooling is probably due to activation of such cells causing increased presynaptic depolarization.
Cholinesterase Activity in Rough and Smooth Brain Microsomal Membranes
Authors: Härkönen Matti , Helve Heikki , Teräväinen Heikki
Published: December 2008

Rat brain cortex was homogenized in 0.25 M or 0.32 M sucrose and sedimented at 10,000 Xg for 20 min. The supernatant was further separated into two subtractions by density gradient centrifugation in Cs+‐containing sucrose. Electron microscopy, RNA/protein and phospholipid/ protein indices showed that one of the subfractions was similar to the rough‐surfaced (R) and the other to the smooth‐surfaced (S) microsomal fractions separated from liver tissue by Dallner (1963). Cholinesterase (ChE) activity was studied by titration. Only 8–13 % of the total ChE activity was recovered in the 10,000 × g supernatant and about 3–6 % in the subfractions. Both the R and S microsomal subfractions displayed ChE activity; however, the S sub‐fraction had about three times as much activity per mg protein as the R subfraction. Activity due to nonspecific cholinesterase was 13 % of the total ChE activity in the R fraction and 7 % in the S fraction when the homogenate was prepared by homogenization with a clearance of 250 urn at 840 rpm. More vigorous homogenization increased the activities. Histochemical staining for AChE and ns. ChE activities revealed reaction product adjacent to both R and S vesicles.
The Effects of “Immunosympathectomy” on Blood Pressure and Vascular “Reactivity” in Normal and Spontaneously Hypertensive Rats
Authors: Folkow Björn , Hallback Margareta , Lundgren Yen , Weiss Lilian
Published: December 2008

Newborn litters of spontaneously hypertensive rats (SHR) and normotensive control rats (NCR) were identically treated with sympathetic nerve growth factor antiserum (Wellcome) which markedly interferes with adrenergic cardiovascular control (Zaimis 1967). Blood pressure, measured intermittently during 8 months, was in treated SHR (SHRis) about 25 % higher than in NCRis, their respective pressures being about 40 % and 25 % lower than those of sham‐treated SHR and NCR.–The hindquarters of one SHRis, or NCRis, were then perfused at constant flow in parallel with those of ordinary NCR. Starting from maximal vasodilatation, resistance increases were induced by graded noradrenaline (NA) infusions, from “threshold” to maximal pressor responses. Compared to NCRis, SHRis showed an increased resistance at maximal dilatation, an increased slope of the NA dose‐response curve and an increased maximal pressor response, while their NA “thresholds” did not differ significantly. Thus, the structurally determined hemodynamic differences between ordinary SHR and NCR (Folkow et al. 1970 b) characterize also SHRis and NCRis, though to a reduced extent. Even when comparing SHRis with ordinary‐ NCR, which exhibited similar “resting” pressures, these differences partly remain, suggesting that the SHR resistance vessels might, for genetic reasons, be more prone to adapt structurally to pressure loads than those of NCR.
Hedgehog Monoamine Oxidase
Authors: Blaschko H.
Published: December 2008

Homogenates of the liver, the kidneys and the brain of the hedgehog, Erinaceus europaeus,. have been tested for monoamine oxidase activity. The enzyme was present in all 3 tissues, and the enzyme was found to act on all the substrates known to be oxidised by other mammalian sources of the enzyme. When the rates of oxidation of tyramine and /?‐phenylethylamine were compared, it was found that the relative rate of the latter amine in liver was about 3 times that found for kidneys. In the brain the position seems to be intermediate.
Effect of Physical Activity on the Metabolism of Collagen in Aged Mice
Authors: Heikkinen Eino , Vuori Ilkka
Published: December 2008

Male mice, 12–14 months old, were exercised on a treadmill daily for an average of 4 weeks. Another group of mice were kept in small cages, in which their motility was considerably limited. A third group served as controls under normal laboratory conditions. Tritiated proline was injected intraperitoneally into the mice at the end of the experimental period, where upon die turnover of collagen and other proteins was measured and the contents of hexosamine, hydroxyproline, nitrogen, calcium, potassium and sodium were determined in various tissues. Metabolism of collagen was increased by exercise and decreased by physical inactivity especially in Achilles tendons and long bones. The ratio of hydroxyproline to nitrogen was highest in the Achilles tendons of the exercised mice. The content of hexosamine was increased by exercise in the skin and decreased by physical inactivity in long bones. No significant differences in the concentrations of calcium, potassium and sodium ions in long bones and in the heart and skeletal muscles were observed. The results show that the metabolism of connective tissues is influenced by degree of physical activity even in relatively old animals.
Influence of Muscle Length on the Mechanical Parameters of Myocardial Contraction
Authors: Nilsson E.
Published: December 2008

Stiffness determinations were made on rabbit papillary muscles at different lengths. Both in resting preparations and in muscles contracting at lengths, where resting force was very low compared with active force, the stiffness increased recti‐linearly with force. At any force level, the stiffness of a preparation was greater at rest than during activity.—Force‐velocity curves were determined at different muscle lengths and, when necessary, data for the whole preparation were corrected for the influence of the parallel elasticity in order to derive the force‐velocity curves of the contractile element alone. Vmax and PO of the contractile element (i.e. its shortening velocity at zero load and its maximum force‐producing capacity) determined at peak isometric force were increased approximately in parallel by elongation at short muscle lengths, whereas at lengths near the optimum for active force, Vmax was influenced slightly more than Po by length changes.—The time course of the active state was critically dependent upon muscle length: an increase in length prolonged the time from stimulation to 60% decay of the active state, without significantly altering the time course of its rising phase.
The Effect of Acetazolamide upon the Regulation of the Cerebrospinal Fluid pH in the Rat
Authors: Messeter Kenneth
Published: December 2008

The influence of large doses of acetazolamide upon the regulation of the CSF pH in normocapnia and hypercapnia was studied in non‐nephrectomized and nephrectomized rats. In non‐nephrectomized animals studied over a 24 h period there was a decrease in the CSF HCO‐3 concentration of 10 mEq/kg. Since the CSF acidosis was far in excess of that usually encountered with a comparable degree of plasma acidosis, the results indicate that acetazolamide inhibited a carbonic anhydrase‐dependent transport of H+or HCO‐3 between CSF and plasma. However, when the fall in plasma [HCO‐3] was prevented by means of a bilateral nephrectomy, acetazolamide did not affect the CSF pH under normocapnic conditions, nor did it retard the accumulation of HCO‐3 in the CSF during hypercapnic conditions. The results do not support any of the existing hypotheses which try to explain the regulation of the CSF pH in both respiratory and non‐respiratory acid‐base disturbances in terms of a common mechanism.
Reactive Hyperemia in Subcutaneous Adipose Tissue in Man
Authors: Nielsen Steen Levin , Sejrsen Per
Published: December 2008

Blood flow in the subcutaneous tissue on the calf was measured with the local Xenon‐133 washout method after varying periods of ischemia. Reactive hyperemia occurred. Maximal flow, cumulative flow, and excess flow were dependent on the duration of the ischemia. The increase in cumulative flow caused by increment in the duration of the ischemic period was characteristic for each individual and was significantly correlated to the resting blood flow. This probably indicates adipose tissue blood flow to be governed by local metabolic factors, as the tissue only shows a limited auto regulatory response.
Effects of Secretin, Cholecystokinin and Caerulein on Gastric Secretion in Response to Sham Feeding in Dogs
Authors: Sjödin Lars
Published: December 2008

Secretin (0.75–3.0 U/kg/h) did not regularly inhibit the acid secretory response to 10 min of sham feeding to a significant degree in 3 dogs with intact antrum. Cholecystokinin (0.75–5.0 U/kg/h) and caerulein (0.06–0.30 μ/kg/h) tended to increase acid output after sham feeding in these dogs. In antrectomized dogs the response to sham feeding was markedly enhanced by cholecystokinin (0.6–2.4 U/kg/h) and caerulein (0.06 μg/kg/h). Pepsin output after sham feeding was increased by secretin (3.0 U/kg/h) and tended to be reduced by cholecystokinin (3.0 U/kg/h) and caerulein (0.30 μg/kg/h). These findings indicate that gastric acid secretion in response to sham feeding is not inhibited by physiological amounts of secretin and in fact increased by cholecystokinin and caerulein. The pepsin output after sham feeding can be enhanced by secretin and possibly depressed by cholecystokinin. The physiological significance of these effects on pepsin secretion remains to be determined.
Influence of Secretin and Cholecystokinin on Canine Gastric Secretion Elicited by Food and by Exogenous Gastrin
Authors: Sjödin Lars
Published: December 2008

The present study showed that in Pavlov pouch dogs gastrin stimulated acid secretion was more markedly inhibited by secretin and cholecystokinin than the secretion elicited by food. The acid secretory response to a test‐meal was only moderately reduced by 3.0 U of secretin/kg/h; the reduction was not statistically significant. In 2 of 3 tested dogs inhibition of the secretion after a test‐meal was more marked when 3.0 U of cholecystokinin (a 10 % pure preparation)/kg/h was administered. However, this dose of cholecystokinin caused some side effects, such as decreased appetite, in the dogs. These doses of cholecystokinin and secretin probably produce unphysiologically high blood levels of the hormones. In spite of the high doses the acid secretory response to a test‐meal was never abolished. This makes it doubtful if these hormones should be regarded as physiologically important inhibitors of gastric acid secretion. Pepsin output after a meal was clearly enhanced by a concomitant infusion of 3.0 U of secretin/kg/h. On the other hand, the same number of units of cholecystokinin markedly inhibited the pepsin output after a meal.