bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inotropic and Metabolic Effects of Dibutyryl Cyclic Adenosine 3‘, 5’‐Monophosphate in the Perfused Rat Heart
Authors: Ahrén Kurt , Hjalmarson ÅKe , Isaksson Olle 
Published: December 2008

AbstractThe isolated, working rat heart preparation was used to study whether dibutyryl cyclic adenosine 3′,5′‐monophosphate could reproduce the inotropic and nietabolic effects of catecholamines in the heart. The effects of dibutyryl cyclic AMP and adrenaline were studied in absence and presence of aβ‐receptor blocking agent (propranolol). Heart rate, cardiac output, peak systolic pressure, glycogen content, lactate production and concentrations of ATP and creatine‐phosphate were measured.Dibutyryl cyclic AMP (5×10‐3M and higher concentrations) evoked a positive inotropic effect as measured by an increase in peak systolic pressure, when the heart rate was kept constant by electrical stimulation. The nucleotide also produced a marked and concentration dependent (10‐5to10‐3) glycogenolytic effect. Propranolol (10‐5M) blocked the inotropic and glycogenolytic effects of adrenaline, but did not reduce the effects of dibutyryl cyclic AMP. The effects of adrenaline were seen already 1 min after its addition to the perfusion medium, while the effects of dibutyryl cyclic AMP were not seen until 3–5 min after addition of the nucleotide. In time course studies, no dissociation was observed between mechanical and metabolic effects of the nucleotide.
Noradrenaline Uptake and Fluorescence Histochemistry in Bovine Splenic Nerves
Authors: Hamberger Bertil , Malmfors Torbjörn , Stjärne Lennart 
Published: December 2008

AbstractA combination of fluorescence histochemical and radiometric methods was used to study the uptake and accumulation of exogenous noradrenaline in the non‐terminal sympathetic axons of isolated bovine splenic nerve trunk. Non‐incubated nerve fibers mostly showed a low fluores cence intensity, but a few fibres exhibited very strong fluorescence with a beaded appearance. The number of beaded axons could be increased by incubation, especially with a‐methyl‐nor‐adrenaline. After incubation, even in amine‐free media, fluorescent material accumulated near the cut ends and also close to areas accidently compressed during the preparation. The results suggest that transport of noradrenaline had occurred under the experimental conditions. In cubation with noradrenaline, particularly after inhibition of monoamine oxidase, or with a‐methyl‐noradrendine, resulted in a strong concentration‐dependent increase of the fluores cence intensity, even in the presence of reserpine. Under the experimental conditions the tissue/ medium ratio was found to be about 60, using 10‐6M racemic3H‐noradrenaline in the in cubation medium. It is concluded that the sons of the bovine splenic nerve trunk possess a reserpine‐resistant mechanism for concentrating noradrenaline which is qualitatively similar to, but quantitatively considerably less efficient than, that previously observed in nerve terminals in other tissues and species.
Oxygen Deficit and Muscle Metabolites in Intermittent Exercise
Authors: Karlsson J. , Saltin B. 
Published: December 2008

AbstractMuscle ATP, CP, ADP, glycogen, G‐6‐P. lactate, and blood lactate concentration were studied in three subjects during intermittent exercise. One min of extremely heavy bicycle work was followed by five min of rest, which was repeated five times. Oxygen uptake was determined continuously and oxygen deficit could be calculated for each activity burst. Oxygen uptake was also measured during the first 60 min of recovery following the last exercise period. The accumulated oxygen deficit increased with each work period. The ratio between oxygen deficit and oxygen debt was 0.55.The breakdown of ATP and CP stores showed progressive phosphagen depletion with each burst of activity while the muscle lactate concentration reached its highest level, ca 23 mmoles × kg‐1 wet muscle, as early as after the first work period. Blood lactate increased gradually during the first 15–20 min of interval periods and then reached a level of 20 mmoles × l‐l. Muscle glycogen concentration was reduced with each work period but did not become completely depleted in any of the subjects. The subjects were as exhausted after the first work period as after the last one. Of the studied metabolic variables muscle lactate concentration was then the one best related to the point of exhaustion.
Lactate in Working Muscles after Prolonged Exercice
Authors: Karlsson Jan 
Published: December 2008

AbstractNearly normal muscle lactate concentrations were obtained with a submaximal work load preceded by prolonged heavy exercise for 2–4 and 5–7 hrs, resulting in a marked decrease in muscle glycogen content. The same was true if prolonged work for 2–4 hrs preceded a standardized supramaximal work test in contrast to prolonged work for 5–7 hrs. In all these studies, however, the blood lactate concentration was reduced after prolonged work, thus con firming earlier findings (Astrand et al. 1963). This might indicate enhanced utilization of blood‐borne lactate induced by the preceding, prolonged work.
Spatial Distribution of Receptor‐Responses to Stimulation with Different Odours
Authors: Mustaparta Hanna 
Published: December 2008

AbstractThe olfactory receptor‐responses recorded from the enzinentia olfactoria in the frog were studied to find whether receptors with different specificities were homogeneously or non‐homogeneously distributed. Receptor potentials (EOGs) were recorded simultaneously from two different areas of the eminentia olfuctoria. 21 different substances were used; 8 of these substances belonged to a homologous serie of cycloketones. For each substance the ratio N between the two EOG‐amplitudes was measured. N‐values obtained with the recording electrodes kept at fixed positions were found to vary for different odours and for different concentrations of the same odour. By recording with one electrode at different distances from the other fixed electrode N‐values for different areas were obtained for each odour. The N‐values showed an increase for some odours and a decrease for others. These observations indicate a non‐homogeneous distribution of receptors with different specificities. For the cycloketones, at the concentrations used, only small variations were found in N‐values at all positions tested. Keeping one electrode fixed and placing the other stepwise away in a posterior or lateral direction, a successive general reduction in N‐values for all the substances was found. This suggests a general reduction in receptor density in posterior and lateral direction.I would like to thank Dr. Kjell Døving for suggesting the topic, and for his constant en couragement during the work.The cycloketones were kindly provided by International Flavor & Flagrances, Holland.
Persistence of Cerebral Blood Flow Autoregulation Following Chronic Bilateral Cervical Sympathectomy in the Monkey
Authors: Eklöf B. , Ingvah D. H. , Kågström E. , Olin T. 
Published: December 2008

AbstractThe cerebral blood flow was measured in 11 monkeys after step changes in arterial blood pres sure in the pressure range 30–140 mmHg. In one group of 5 animals a bilateral excision of the superior cervical ganglia was performed about 2 weeks prior to the experiment. These animals, as well as those with an intact sympathetic innervation of the cerebral vessels, demonstrated an almost constant rCBF at pressures above 50–60 mmHg,2.e. both groups showed autoregulation. It is concluded that cervical sympathectomy does not abolish autoregulation of the cerebral blood flow.
Influence of Changes in Microcirculation on the Excitability of the Sensory Unit in the Tooth of the Cat
Authors: Edwall Lennart , Jr Donald Scott 
Published: December 2008

AbstractSimultaneous determinations of radioactive iodide disappearance rate (k‐value) and sensory nerve impulse frequency from dentinal cavities were performed on canine teeth of anesthetized cats. Changes in k‐value reflecting changes in pulpal microcirculation were obtained by direct sympathetic nerve stimulation or by thermal stimulation. Sympathetic nerve stimulation re duced the k‐value and induced an initial increase in nerve impulse frequency. During maximal sympathetic nerve stimulation this initial increase was followed by a marked depression in impulse frequency. Application of heat increased k‐value as well as impulse frequency, while cold reduced k‐value and induced an initial increase in nerve impulse frequency followed by a decrease. Thermal stimulation superimposed during maximal sympathetic stimulation, when k‐value was depressed, was inadequate to evoke an appreciable increase in sensory nerve in pulse frequency. It is suggested that the excitability of sensory units in the tooth is strongly modulated by changes in pulpal microcirculation induced by, for example, stimulation of sympathetic vasoconstrictor fibres.
Regulation of the CSF pH in Acute and Sustained Respiratory Acidosis
Authors: Messeter Kenneth , Siesjö Bo K. 
Published: December 2008

AbstractIn order to study the regulation of the cerebrospinal fluid pH during hypercapnia, plasma and CSF acid‐base parameters were measured in rats exposed to about 11% CO2 for periods varying from 5 min to 5 days. When combined with previously measured CSF‐plasma d.c. potential differences, the plasma and CSF pH values and bicarbonate concentrations could be used to calculate electrochemical potential differences (δμ) for H+ and HCO3‐ between CSF and plasma. Hypercapnia lead to a 20 mEq/kg increase in the CSF bicarbonate concentration, most of which occurred during the first 24 h. There was a somewhat larger [HCO3‐] increase in the CSF than in plasma water but in none of the compartments did the pH normalize. In acute hypercapnia (5–180 min) the calculated δμH+ and δμHCO3 values changed in a direction which would favor influx of HCO3‐a into the CSF. In the sustained groups (24–120h) the δμ's were close to the normocapnic control values. Since the accumulation of bicarbonate in the CSF occurred at a time when there was a suitable “passive” diffusion gradient, and since the CSF [HCO3‐] in the chronic state was upheld without a significant change in the δμ's, it is concluded that the regulation of the CSF pH in hypercapnia does not seem to require active transport of H+ or HCO3‐.
Modification of Kaolin‐Induced Intracranial Hypertension at Various Time‐Periods after Superior Cervical Sympathectomy in Rabbits
Authors: Edvinsson L. , Owman Ch. , West K. A. 
Published: December 2008

AbstractThe intracranial pressure measured as the ventricular fluid pressure (VFP) was recorded continuously via a cannula in the left lateral ventricle of the brain of conscious rabbits 2 days after intracisternal administration of kaolin, known to induce intracranial hypertension. The effect of sympathectomy was studied at various time‐periods after bilateral removal of the superior cervical ganglia: (a) During a 2‐day recording period following shortly after sympathectomy the VFP of kaolin‐treated animals was considerably lower compared to non‐sympathectomized, kaolin‐treated animals, (b) One week after sympathectomy the VFP was initially lower than in the non‐sympathectomized controls. However, it rapidly increased to very high levels, and all animals died within 10 hours after the recording was started, (c) About 2 weeks after sympathectomy the pressure tended to be lower than in the non‐sympathectomized control animals. It is suggested that these findings are mainly the result of changes in the intracranial blood volume (although direct effects of the sympathectomy on cerebrospinal fluid circulation can not be excluded). Thus, shortly after sympathectomy–period (a)–when the transmitter is leaking from the degenerating nerves, the intracranial vessels contract and the blood volume decreases. In addition, the intracranial hypertension has probably resulted in a compensatory increase in cerebrospinal fluid absorption and/or reduction in its formation, which will further lower the VFP. Period (b): the denervated vessels dilate and the increased intracranial blood volume will add to the intracranial hypertension caused by the blocked cerebrospinal fluid circulation and the edema produced by the implantation of the pressure cannula. Period (c): the brain vessels have developed a pronounced denervation supersensitivity to circulating catecholamines, the vascular tone is enhanced and the reduced blood volume will tend to lower the VFP.
The Influence of Noradrenaline Synthesis Inhibition on the Disposition of3H‐Metaraminol in Peripheral Adrenergic Nerves
Authors: Almgren Olle 
Published: December 2008

AbstractThe disappearance of dl‐metaraminol‐7‐3H (3H‐MA) from intact and decentralized rat salivary glands and from rat hearts after an i.v. injection of 40 μg/kg of the amine was studied. One group of rats received 500 mg/kg i.p. of an inhibitor of noradrenaline synthesis, α‐methyltyrosine methylester (H 44/68), 1 h before the amine injection and thereafter repeated injections every 12 h. The rats not treated with the synthesis inhibitor served as controls. The initial phase of the normally two‐phasic exponential disappearance of3H‐MA from intact glands was markedly retarded by H 44/68 treatment. Also the3H‐MA disappearance from the decentralized glands was retarded by H 44/68 treatment, while the disappearance from the heart was not significantly affected. It is suggested that3H‐MA is undergoing continuous displacement from storage sites by newly synthesized transmitter. After H 44/68 treatment such displacement no longer occurs.
Effect of Amphotericin B on the Frog Skin in vitro. Evidence for Outward Active Potassium Transport across the Epithelium
Authors: Nielsen Robert 
Published: December 2008

AbstractIt is shown that amphotericin B (5×10‐5 M) increases the permeability of the frog skin to potassium, chloride and urea. The potassium flux was more strongly increased from the inside to the outside than from the outside to the inside of the skin, whereas the chloride and the urea fluxes were equally enhanced in both directions. The increased potassium flux from the inside to the outside could not be explained by a potassium loss from the cells. It is suggested that a part of the high outward potassium flux was due to an active outwards transport of potassium.
Release of Noradrenaline from the Dog Heart In Situ after Intravenous and Intracoronary Administration of 5‐Hydroxytryptamine
Authors: Pillion Gilles M. B. , Lluch Salvador , Uvnäs Börje 
Published: December 2008

AbstractThe following experiments have been carried out in order to establish the validity of the hypothesis that the cardiac stimulatory effects of 5‐hydroxytryptamine (5‐HT) are mediated by catecholamines. Release of cardiac noradrenaline (NA) has been observed after administration of 5‐HT either intravenously or intracoronarily. After labelling the heart with3H‐5‐HT, it was possible to release this amine by cardioaccelerator nerve stimulation even after treatment with an adrenergic β blocker. It is concluded that the cardiac stimulatory effects of 5‐HT are mediated by NA; this NA is mainly derived from sympathetic nerve endings by intra‐neuronal exchange for 5‐HT.
The Role of the Adrenal Medulla in Posthemorrhagic Pulmonary Hypertension
Authors: Bø G. , Hognestad J. 
Published: December 2008

AbstractA marked increase in pulmonary vascular resistance (PVR) is known to develop in cats during hemorrhagic hypotension. The present investigation is an attempt to evaluate the role played by adrenal catecholamines in this posthemorrhagic PVR‐development. Anesthetized cats with open chests and on positive pressure ventilation were used. Six animals in which the adrenals had been acutely denervated were bled until the mean arterial pressure was 50 mm Hg. This level of hypotension was maintained for 3 h by further bleedings and/or small retransfusions. Cats similarly treated received catecholamines continuously infused (5 μg/kg/min) during the hemorrhagic period. Adrenaline alone, noradrenaline alone, or a 1:4 mixture of the two catecholamines were used. Comparisons were carried out between these animals and animals similarly bled but with intact adrenal innervation.In the cats with denervated adrenals the posthemorrhagic rise in PVR was low as compared with the high level seen in animals with intact adrenals. The gradual fall in the number of circulating thrombocytes was also significantly less in the denervated group than in the control group. Infusions of catecholamines to animals with denervated adrenals caused pulmonary hypertension in the hemorrhagic period. These findings indicate that catecholamines released from the adrenals play an important role in the development of the posthemorrhagic pulmonary hypertension previously described.
Comparison of the Effects of Prostaglandins E1, E2and F2αon the Sympathetically Stimulated Rabbit Heart
Authors: Hedqvist Per , Wennmalm ÅKe 
Published: December 2008

AbstractPGE1, PGE2and PGF2αin concentrations ranging from 3×10‐9M to 1.5 × 10‐6M were infused into the isolated perfused, sympathetically innervated rabbit heart in order to assess their capacity to inhibit the chronotropic, inotropic and noradrenaline overflow responses to sympathetic nerve stimulation, as well as the chronotropic and inotropic responses to infusion of noradrenaline. The coronary flow was increased by PGE1but not by PGE2of PGF2α. The three compounds did not change the heart rate or the contractile force, indicating that the reported increase in heart rate after i.v. infusion of PGE1or PGE2is reflex in origin. PGE1and PGE2inhibited the outflow of noradrenaline as well as the chronotropic and inotropic responses to nerve stimulation in a dose‐dependent way, while PGF2αwas ineffective. None of the compounds altered the chronotropic or inotropic response to exogenous noradrenaline. It is concluded that PGE1and PGE2but not PGF2α, inhibit the sympathetic neurotransmission in the rabbit heart, and that they do this mainly by reducing the release of the transmitter from the adrenergic nerve terminals.
Uptake of Serotonin in Blood Platelets in vitro. II: Further Studies on the Effects of Small Anions
Authors: Lingjærde O. 
Published: December 2008

AbstractAccording to previous reports, serotonin (5HT) uptake in human blood plateletsin vitrorequires the presence of chloride. Chloride can be replaced by other small univalent, but unphysiological anions, such as (in decreasing order of effectiveness) bromide, nitrite, iodide, nitrate, and formate, However, the effect of nitrite, especially, is kinetically different from that of chloride. Whereas the effect of chloride obeys simple Michaelis‐Menten type kinetics, increasing concentrations of nitrite give a sigmoidal 5HT uptake curve. Moreover, the effects of nitrite and chloride are partly additive. It is suggested that these effects of nitrite can be explained by assuming that nitrite, besides being able to replace chloride in the so‐called “anionic site” of the carrier, also has an effect on a hypothetical “activating site”. This simple model cannot, however, easily explain all the complex interactions between chloride and nitrite. It is also reported that preincubation with different anions affects the uptake rate to very varying degrees, and that the anions have somewhat different effects on spontaneous 5HT outflux.
Choroid Plexus Uptake of Atropine and Methylatropine in vitro1
Authors: Eriksson K.‐H. , Winbladh B. 
Published: December 2008

AbstractRabbit choroid plexa in vitro accumulate tritium labelled atropine and methylatropine by a mechanism which fulfils the conventional criteria for active transport. The two drugs seem to share the same carrier with other tertiary and quaternary amines investigated, i.e. morphine, promethazine, choline, hexa‐and decamethonium. The ratios for telencephalic choroid plexus tissue: medium were 10 for atropine and 65 for methylatropine at an incubation medium concentration of 10‐4 M. Maximal velocity of uptake was in the order of 0.35 mmol/kg × min for atropine and 0.26 mmol/kg × min for methylatropine while apparent Km was 0.9 mM and 0.08 mM respectively. The results are discussed in relation to other reports of choroid plexus transport mechanisms and their possible physiological meaning.
The Effect of Acute and Chronic Hypercapnia upon the Lactate, Pyruvate, α‐ketoglutarate, Glutamate and Phosphocreatine Contents of the Rat Brain
Authors: Messeter Kenneth , Siesjö Bo K. 
Published: December 2008

AbstractThe influence of hypercapnia upon the tissue contents of lactate, pyruvate, α‐ketoglutarate, glutamate and phosphocreatine was studied in rats exposed to about 11 % CO2 for 15 and 45 min, and for 3, 24, 48 and 72 h, respectively. Acute hypercapnia (15 and 45 min) was associated with highly significant decreases in the lactate, pyruvate, α‐ketoglutarate, glutamate and phosphocreatine contents. In sustained hypercapnia (3 h and onwards), the lactate, pyruvate and α‐ketoglutarate contents were partially restored but phosphocreatine and glutamate remained decreased. In acute hypercapnia the intracellular lactate/pyruvate ratio was increased, but it returned to normal in sustained hypercapnia (> 24 h). The results suggest that the intracellular lactate/pyruvate ratio is affected both by changes in the intracellular pH and by changes in the NADH/NAD+ ratio.
Chemical Composition of Basophil Granules from Isolated Rat Mast Cells
Authors: Bergqvist Ulla , Samuelsson Gunnar , Uvnäs Börje 
Published: December 2008

AbstractA protein fraction was isolated from rat mast cell granules. Disc gel electrophoresis and peptide mapping showed this fraction to be a mixture of 1 or 2 main components and 2–3 minor components. On ultracentrifugation the protein fraction behaved as an homogeneous material with a molecular weight of 5600. Amino acid analysis showed the presence of all the common amino acids (with the possible exception of tryptophan). High contents of lysine, aspartic acid, glutamic acid, proline, glycine and valine were noted. The content of cysteine was remarkably low. The isoelectric point of the main component(s) was found to be around 9.
The Hemodynamic Consequences of Regional Hypotension in Spontaneously Hypertensive and Normotensive Rats
Authors: Folkow Björn , Gurévigh Moisie , Hallbäck Margareta , Lundgren Yen , Weiss Lilian 
Published: December 2008

AbstractIn 3 week old spontaneously hypertensive rats (SHR) and normotensive control rats (NCR) the aorta was ligated distally to the renal arteries, lowering the blood pressure in the hindquarters some 30–50 per cent compared with “ordinary” NCR or SHR. 6–16 weeks later the hindquarters of an ordinary NCR were perfused simultaneously with those of an aorta‐ligated NCR or SHR in 20 paired experiments at constant flow with an oxygenated plasma substitute, from maximal dilatation to maximal constriction as induced by graded noradrenaline (NA) doses. Constructed “resistance curves” of the aorta‐ligated NCR and SHR hindquarters showed a 40–50 % decreased resistance at maximal dilatation with almost proportional decreases of the steepness of the dose‐response curve and of the maximal pressor response, when compared with ordinary NCR, while the threshold sensitivity to NA was the same as in unligated shamoperated NCR. The difference from unligated SHR was still more striking, yielding three separate sets of “resistance curves” each related to the pressure level present in the hindquarters during the months prior to the perfusion. The results indicate an adaptive structural change of the resistance vessels in the chronically hypotensive hindquarters with a media reduction and considerably increased vascular lumina. Thus, the elimination of the pressure load seems capable of completely preventing the development of the adaptive media increase that otherwise seems to occur in SHR. An altered pressure load, decreased or increased, evidently affects the design of the resistance vessels rapidly and this, in turn, will greatly contribute to the hemodynamic differences characterizing hypo‐ and hypertension as compared to normotension.