bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interaction between the Fastigial Pressor Response and the Baroreceptor Reflex
Authors: Lisander Björn , Martner Jan 
Published: December 2008

AbstractExperiments 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

AbstractThe 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

AbstractIn 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

AbstractIn 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

AbstractElectrical 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

AbstractThe 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

AbstractThe 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

AbstractEstimations 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

AbstractDinitrophenol (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

AbstractWhen 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

AbstractChlorpromazine (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

AbstractThe 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

AbstractThe 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

AbstractRecently 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

AbstractMulti‐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

AbstractWith 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

AbstractSegments 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

AbstractThe 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

AbstractFree 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

AbstractBranemark, 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.