bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pineal Serotonin Metabolism in Non‐Innervated Perinatal Glands before and after Intraocular Maturation: Supersensitivity of Adrenoceptors that have never been Innervated
Authors: Bäckström Maria , Olson Lars , Seiger ÅKe 
Published: December 2008

AbstractTransplantations were made of fetal pineal glands (crown‐rump length, CRL, 19–30 mm) or pineal glands from adult male rats to the anterior chamber of the eye of the rat. Studies were performed with regard to the importance of the age of the donor animal (and thereby the degree of maturation and innervation of the gland to be transplanted) for the possible development of denervation supersensitivity. The transplants were cultured in a medium containing14C‐serotonin. Increased production of14C‐N‐acetylserotonin (NAcS) was used as the main criterion for β‐adrenergic stimulation. 4 experimental groups were obtained by transplanting fetal or adult pineals to intact or sympathetically denervated eyes. In all 4 groups β1‐stimulation (KWD 2033 10‐6M) increased14C‐NAcS formation. The response to β‐stimulation was significantly higher in denervated fetal pineal transplants than in innervated fetal transplants and thus demonstrating β‐receptor supersensitivity. It was concluded that a) the ability to respond to β‐adrenoceptor stimulation with increased14C‐NAcS formation develops between the 18th and 20th day of gestation, b) transplants derived from fetal as well as from adult rats can respond to β‐adrenergic stimulation, c) this sensitivity also developsin oculoin transplants that at the time of transplantation lacked the capacity to increase their14C‐NAcS formation in response to treatment with β‐agonist, d) denervation supersensitivity occurs in fetal transplants that became mature in sympathetically denervated eyes.
Preferential Uptake of 14C‐α‐Aminoisobuturic Acid into Mouse Uterine Tissue during Early Pregnancy
Authors: Lindqvist Iinger , Nilsson Ove , Ronquist Gunnar 
Published: December 2008

AbstractThe uptake of 14C‐AIB into uterine tissue and some other organs was studied during early implantation. Mice in experimentally delayed implantation were given estrogen and 14C‐AIB at different time intervals. Mice in delayed implantation given only 14C‐AIB displayed a low transport rate into the uterine tissue, comparable with that for the diaphragm muscle. However, if the estrogen injection preceeded that of the 14C‐AIB by 4 to 8 h the transport capacity increased by a factor of at least 4 times while the uptake for the diaphragm muscle remained low. Under such conditions 14C‐AIB‐accumulation into uterine tissue was favoured for at least 4 h of in vivo incubation with the labeled amino acid.
Regulation of Respiration: “The Black Box”
Authors: Asmussen Erling 
Published: December 2008

AbstractA close relation between the state of wakefulness, the electroencephalogram, and the respiration has been demonstrated (Bülow 1963). In the present paper it was assumed that as opening and closing of the eyes influence the EEG and thus probably the state of wakefulness, the responsiveness of the respiratory center may likewise be influenced by the single act of closing the eyes. Seven subjects were studied in the steady state of rest breathing ambient air, 4–5 % CO2 in air, or 11 % O2 in nitrogen. In experimental periods of 4–5 minutes their pulmonary ventilation and alveolar Pco2 were measured while they randomly were either reading a book, or were blindfolded. It was found that in all three conditions closing of the eyes resulted in a mean decrease of VE of 8 to 14 % with a concomitant increase of PACO2 of about 1 mmHg. It is tentatively suggested that other and stronger central or peripheral stimuli impinging on the reticular formation of the brain may explain the changed sensitivity of the respiratory center towards the chemical stimuli in conditions like exercise, chronic hypoxia etc.
Time Course of Changes in Human Skeletal Muscle Succinate Dehydrogenase and Cytochrome Oxidase Activities and Maximal Oxygen Uptake with Physical Activity and Inactivity
Authors: Henriksson Jan , Reitman James S. 
Published: December 2008

AbstractSuccinate dehydrogenase (SDH) and cytochrome oxidase activities in the lateral vastus of the human quadriceps femoris muscle together with total body V́o2 max were followed during an 8–10 week period of endurance training (n=13) and a successive 6 week period without training (n = 8). During the training period there was a gradual increase in both Vo. max and muscle oxidative enzyme activities, all being significantly different from the pre‐training levels after 3 weeks of training. After 8 weeks of training V́o2. max was 19%, vastus lateralis SDH 32%, and cytochrome oxidase activity 35% above the pre‐training levels respectively. 6 weeks post‐training V́o3 max was still 16% above the pre‐training level, and not signifi‐ficantly different from the level at the end of training (p >0.2). In contrast vastus lateralis SDH activity had returned to the pre‐training level. Cytochrome oxidase activity had returned to the pre‐training level within two weeks post‐training. The significantly faster post‐training decline in skeletal muscle oxidative enzyme activities in contrast to that of the V́o2 max indicates that an enhancement of the oxidative potential in skeletal muscle is not a necessity for a high V́o2 max. Moreover, the fast return to the pre‐training level of both SDH and cytochrome oxidase activities indicate a high turnover rate of enzymes in the TCA cycle as well as the respiratory chain.
Choline Acetyltransferase Activity in Parotid Glands of Rats after Prolonged Treatment with Pilocarpine
Authors: Ekström Jörgen 
Published: December 2008

AbstractThe enzyme activity, expressed as total activity and concentration, was found to be decreased in the cholinergic neurones of the glands after treatment with pilocarpine for 10 days. The secretion of saliva evoked by the parasympathomimetic drug is thought to have reduced the reflex stimulation of the glands via the cholinergic secretory nerves and thereby lowered the enzyme activity in the nerves.
Twenty‐Four Hour Variation in Flow and Composition of Leg Lymph in Normal Men
Authors: Engeset A. , Olszewski W. , Jæger P. M. , Sokolowski J. , Theodorsen L. 
Published: December 2008

AbstractThe twenty‐four hour variation in concentration and output of total protein, lactate dehydrogenase and alkaline phosphatase has been studied in the peripheral lymph from the legs of 5 healthy volunteers over a period of five days. The highest concentration of these proteins was found in lymph collected during the first two hours after a night's rest. During the day a continuous decrease in concentration occurred without any direct correlation to lymph flow. The variation in lymph protein concentration between early morning and late day was about 40 %, lactate dehydrogenase and alkaline phosphatase about 90% and 45o, respectively.
Time Course and Extent of Carotid Sinus Baroreceptor Threshold Resetting in Rats with Renovascular Hypertension
Authors: Jones John V. 
Published: December 2008

AbstractTo study the extent and time course of arterial baroreceptor threshold resetting to increases in blood pressure, renal hypertension was induced in young normotensive male Wistar rats by unilateral renal artery constriction. At different intervals after operation the extent of baroreceptor threshold resetting in the carotid sinus was examined. Experiments were performed 7, 14 and 25 days after renal artery clipping to enable baroreceptor resetting to be correlated with the rate and extent of cardiovascular changes in rats which had renovascular hypertension of identical durations (Lundgren et al. 1974). Baroreceptor thresholds in the carotid sinuses were established by progressive clamping of both carotid arteries after partial vascular isolation of the sinuses. The results show that after one week of hypertension baroreceptor resetting is only just apparent but by two weeks resetting is gross and seems to be largely completed. This parallels the adaptive changes in the hindquarters of renal hypertensive rats and it is concluded that baroreceptor resetting is a secondary phenomenon related to the structural changes induced in the vessels by the elevated blood pressure.
Conjugated Catechol Derivatives in a Transplantable Islet Cell Tumour of the Golden Hamster
Authors: Falck B. , Hansson C. , Kennedy B.‐M. , Rosengren E. 
Published: December 2008

AbstractTwo glucuronidated catechol derivatives have been identified in a transplantable islet cell tumour of the golden hamster,i.e.dopamine‐4‐O‐glucuronide and 3‐methoxytyramine‐4‐O‐glucuronide. L‐dopa is rapidly metabolized in the tumour to one or both of these glucuronides. Incubation of tumour homogenates in the presence of β‐glucuronidase shows that dopamine‐4‐O‐glucuronide is present in the tumour in extremely high concentrations.
Lactate in Fast and Slow Twitch Skeletal Muscle Fibres of Man during Isometric Contraction
Authors: Tesch Per , Karlsson Jan 
Published: December 2008

AbstractConcentrations of lactate in fast and slow twitch fibres, respectively, were determined in m. quadriceps femoris after sustained contractions at 25%, 50%, and 75% of maximal voluntary isometric contraction (MVC) until exhaustion as well as after interrupted exercises at 25 % and 50 % MVC. Maximal lactate concentrations were only found at 50% of MVC performed to exhaustion. Lactate concentration was higher in slow twitch (ST) fibres at 50% MVC compared to in ST fibres at 25% MVC, and higher in fast twitch (FT) fibres at 50% MVC compared to in FT fibres at 75 % MVC. After short time isometric exercise (i.e. 75% to exhaustion and 50% and 25% performed for the same period of time as 75% MVC) lactate concentration, expressed as lactate ratio (lactate concentration in FT fibres/lactate concentration in ST fibres) was found to be positively correlated to percent FT fibres (r = 0.89). Lactate ratio ranged 0.5‐2.0, i.e. at onset of isometric exercise, lactate concentration increase was faster in ST fibres in the muscle rich in ST fibres and faster in FT fibres when the muscle was rich in FT fibres.
Effect of Changes in Blood Volume Distribution on Circulatory Variables and Plasma Renin Activity in Man
Authors: Bevegård Sture , Castenfors Jan , Lindblad Lars Erik 
Published: December 2008

AbstractIn 8 healthy subjects the pressure around the lower body was changed to 40 mmHg above (LBPP) and below (LBNP) atmospheric, thereby altering the amount of blood pooled in the lower body. Heart rate, intraarterial blood pressure, central venous pressure, cardiac output (dye dilution technique) and forearm blood flow (venous occlusion plethysmography) were measured. Plasma renin activity was determined with a radioimmunological method. 6 subjects maintained a relative circulatory steady state during LBNP. LBNP caused significant decreases in central venous pressure (CVP), stroke volume and cardiac output (0) with an unchanged mean arterial pressure (MAP). Heart rate (HR) increased significantly. Calculated total peripheral vascular resistance (TPVR) and regional vascular resistance (RVR) in the forearm were significantly increased when measured 5–9 min after the onset of LBNP, whereas plasma renin activity (PRA) showed a definite increase only after 19 min of LBNP stimulation. No correlation was found between the changes in PRA and TPVR or RVR. Increasing the pressure around the lower body (LBPP) resulted in a slight but significant increase in MAP as well as a significant but transient increase in CVP. No significant changes were found in HR, Q or TPVR. In the forearm a decrease in RVR was demonstrated. PRA was not significantly changed. The results demonstrate that peripheral vascular resistance and PRA are both influenced by changes in blood volume distribution, possibly elicited via intrathoracic receptors sensitive to changes in central blood volume and/or CVP. The results also suggest that PRA does not play any significant part in the vasoconstriction during LBNP stimulation.
Renal Hemodynamics in the Perinatal Period
Authors: Aperia Anita , Broberger Ove , Herin Peter , Joelsson Ingemar 
Published: December 2008

AbstractThe perinatal changes in renal hemodynamics have been studied in lambs. Eleven of the lambs were exteriorized, but maintained on placental circulation (fetal lambs). Eight of the lambs were delivered with cesarean section and studied immediately after clamping of the cord (newborn lambs). Nine lambs were delivered spontaneously and studied during the first 9 days of life. Renal blood flow (RBF) was determined by the microsphere method using a sample drawn from the iliac artery as the reference flow. The filtering capacity of the nephrons was evaluated after ferrocyanide injection and dissection of the nephrons. Total RBF did not seem to change much at birth but increased in relation to kidney weight during the first postnatal week. Clamping of the cord did, however, result in a change in intrarenal blood flow distribution, so that in the newborn lambs relatively more of the blood flow was perfusing the outer cortical region. During the first postnatal week there was a slight, but insignificant further relative increase in outer cortical blood flow. The relative increase in outer cortical blood flow at birth was accompanied by an increased frequency of filtering superficial nephrons from 22 to 77 %. Practically all juxtamedullary nephrons were filtering before birth. Three days postnatally 98 % of the superficial and 100 % of the juxtamedullary nephrons were filtering.
Effects of Acetylsalicylate on Alkalinization, Acid Secretion and Electrogenic Properties in the Isolated Gastric Mucosa
Authors: Garner Andrew 
Published: December 2008

AbstractThe effects of acetylsalicylate (ASA) on the in vitro secretory and electrical properties of Necturus and Rana temporaria gastric mucosa have been studied. The gastric antrum alkalinized the luminal surface, while in the fundus it is likely that acidification and alkalinization occur simultaneously and that net secretion is due to the dominance of one or other of these processes. The histamine H2 receptor antagonist Metiamide was used to inhibit acid secretion for studies on fundic alkalinization in Rana temporaria. Submucosal application of 3 mM ASA for 30 min markedly reduced alkalinization in the antrum and the frog fundus. Following removal of ASA there was only partial recovery of this secretion. The drug caused slight inhibition of spontaneous acid secretion in Necturus fundus but not of histamine‐stimulated acid secretion in the frog fundus. Following salicylate removal, the rate of acid secretion increased to a higher level than before administration in both tissues. There was a small flux of ASA across the mucosa which was greatest in the acid secreting frog fundus (4.38μmol cm‐2 min‐1) and least in the antrum (2.19μmol cm‐2 min‐1). Exposure of the gastric mucosa to ASA was generally associated with a fall in transmucosal electric potential difference and short‐circuit current together with an increase in electrical resistance. It is proposed that the greater sensitivity of alkalinization to ASA is responsible for the apparent increase in the rate of acid secretion which occurred.
Adrenergic and Cholinergic Nerves of the Human Urethra and Urinary Bladder. A Histochemical Study
Authors: Ek A. , Alm P. , Andersson K.‐E. , Persson C. G. A. 
Published: December 2008

AbstractThe occurrence and distribution of adrenergic and acetylcholine esterase (AChE) positive nerves in the human urethra and urinary bladder were studied histochemically with the fluorescence method of Falck and Hillarp, and the copper thiocholine method of Koelle and Friedenwald. Both types of nerves were mainly confined to the layers of smooth muscle cells in the walls of the organs. In all parts of the urethra, there was a scanty supply of adrenergic nerves. Few adrenergic nerves were also found in the urinary bladder, except in the trigone area, where they were abundant. AChE‐positive nerves were uniformly and richly distributed in the urinary bladder. Throughout the urethra the distribution of AChE‐positive nerve fibres was uniform, but the number was clearly less than in the urinary bladder. No intramurally located adrenergic or AChE‐positive ganglion cells could be demonstrated.
The Effects of Variations in Extracellular Magnesium Concentration on Electrical and Mechanical Activity in Rat Portal Vein
Authors: Sigurdsson Stefan B. , Uvelius Bengt 
Published: December 2008

AbstractThe effects of various concentrations of extracellular Mg2+ on electrical and mechanical activity of the rat portal vein were studied. The integrated spontaneous contractile activity in the preparation was largest in Mg2+‐free solution, decreased to about 50 %at 1.2 mM Mg2+ and was almost completely abolished at 10 mM Mg2+. Each spontaneous contraction became smaller whereas contraction frequency was less affected. Sucrose gap recordings showed that the reduced spontaneous mechanical output was associated with decreased electrical activity on increasing [Mg2+]0. Increasing [K+]0 from 6 to 12 mM normalized the spontaneous mechanical activity in 10 mM Mg2+ solution. Local registration of electrical activity with 3 extracellular glass capillary electrodes showed that inactive areas developed at the high Mg2+ concentrations. These findings indicate that Mg2+ exerts a hyperpolarizing action on the smooth muscle cell membrane and, at the highest concentration, interferes with intercellular propagation. [Mg2+]0 in the range of 0–10 mM had no effect on the amplitude of K+ (122 mM) contractures at [Ca2+]0± 0.5 mM. At [Ca2+]0 < 0.5 the amplitude diminished with increasing [Mg2+],. The latter observation indicates that Mg2+ can interfere with the Ca2+‐permea‐bility of the depolarized cell membrane. 1 mM EDTA in Na‐tris 0 mM Mg2+ and 0 mM Ca2+ seemed to lower intracellular Mg2+ below the minimum concentration needed for contractile activity.
Extracellular Potassium Concentration in Juvenile and Adult Rat Brain Cortex during Anoxia
Authors: Hansen Anker Jon 
Published: December 2008

AbstractThe extracellular K concentration, ([K]e), in the brain cortex of rats at different ages was measured by means of K+‐sensitive microelectrodes. [K]e was between 3 and 5 mM at all ages. Following nitrogen inhalation there was an increase in [K]e which exhibited a sigmoid pattern in every age group: Firstly, there was a slow rate of rise which was followed by a sudden, steep increase where the [K]e rose to about 70 mM. During the subsequent 5–10 min a plateau value of about 90 mM was reached. The prominent difference between the age groups was the time until the steep rise began. The time to the steep increase in [K]e and the [K]e at the start of the steep increase was inversely related to the age of the animal. A close relation was found between the time to the start of the steep increase and the time to the last gasp during nitrogen breathing (r ‐ 0.98). It is suggested that the different resistence to anoxia in young and adult animals is related to differences in the ability to keep near normal potassium gradients across the cells in the brain.
Distribution of Coronary Blood Flow in the Left Ventricular Wall of Dogs Evaluated by the Uptake of Xe‐133
Authors: Bagger Henning 
Published: December 2008

AbstractThe distribution of coronary blood flow was estimated in anesthetized dogs by counting the activity in tissue blocks of the left ventricular free wall immediately after bolus injection of Xe‐133 into the aortic root. No differences in the uptake of isotope were observed between the apex and the base of the heart; between areas supplied by the anterior descending and circumflex branches of the left coronary artery; or between the endo‐ and epicardial halves of the wall. In most experiments a bolus injection of the isotope into the left coronary artery was followed by a difference in activity between areas supplied by the left anterior descending and left circumflex branches. This indicated inadequate mixing of blood and isotope in the main stem of the artery. The uneven distribution did not result in differences between the epi‐ and endocardial activity concentrations. The results from one normal, anesthetized dog in which tissue activities were measured after constant rate infusion of Xe‐133 into the left coronary artery for 8 min were in accordance with the general assumption of equal epiand endocardial volumes of distribution (values of Zs).
Effect of Hypoxia on Mitochondrial Mass and Cytochrome Concentrations in Rat Heart and Liver during Postnatal Development
Authors: Kinnula Vuokko L. , Hassinen Ilmo 
Published: December 2008

AbstractCytochrome concentrations of rat heart and liver mitochondria were measured postnatally from newborn animals to young adults. Mitochondrial cytochrome aa3 concentration increased shortly after birth in both tissues, this concentration being in a newborn animal 0.149 ± 0.027 nmol/mg protein in liver and 0.333 ± 0.082 nmol/mg protein in heart. The respective values from a two week old animal were 0.216±0.031 and 0.583 10.100. Postnatally cytochromes c±c1 and b increased markedly in the heart, but in the liver of newborn animals the cytochrome content was more close to the adult values. The amount of mitochondrial protein increased after birth, too. In a newborn animal the mitochondrial protein values were 39.7 ± 3.6 mg/g wet weight in liver and 26.6± 6.5 mg/g wet weight in heart. In adult animals the respective values were 71.5 ± 4.8 and 80.7± 13.1. The effect of postnatal hypoxia (10% O2, 24 h and 48 h) on liver and heart mitochondrial cytochrome concentration and protein values of newborn animals were investigated. During hypoxia the amount of mitochondrial protein remained about at the level of a newborn animal. The postnatal increase in the mitochondrial cytochrome concentration, which was smaller in the liver than in the heart, was also inhibited by hypoxia.
The Ability of ATP‐Free Granule Material from Bovine Adrenal Medulla to Bind Inorganic Cations and Biogenic Amines
Authors: Uvnäs Börje , ÅBorg Carl‐Hugo 
Published: December 2008

AbstractBovine adrenal medullary granules isolated by miliipore filtration were depleted of CA and ATP by dialysis. The resulting material showed an ability to bind inorganic cations and biogenic amines in a concentration‐dependent manner. The similarity of the uptake curves, the identical uptake maxima and the narrow pH range (between 4–7) over which the uptake of the inorganic and organic cations took place indicated a binding of these ions to common sites. In addition, the fact that all the uptake curves fitted the Rothmund‐Kornfeld equation for cation exchangers corroborated the cation exchanger properties of the dialyzed granule material. The CA binding capacity corresponded to 20–30% of the normal CA content of bovine medullary granules.
Indirect vascular actions of (Gln4)‐neurotensin in canine adipose tissue
Authors: Rosell Sune , Rökaeus ÅKe , Ding Chang  , Folkers Karl 
Published: December 2008

AbstractThe vasoconstrictor action of the tridecapeptide (Gln4)‐neurotensin has been studied in subcutaneous adipose tissue in the inguinal region of anesthetized dogs. Close intra‐arterial infusion of (Gln4)‐neuroten‐sin, 30–120 pmol X kg‐1 b.wt. X min‐1, elicited similar vasoconstrictions in the adipose tissue on the infusion side and on the contralateral side. This suggests that (Gln4)‐neurotensin must enter the general circulation before it can elicit vasoconstriction. Removal of parts of the gastrointestinal tract did not change the vasoconstrictor response. Thus, there is no indication of release of vasoactive substances from the gastrointestinal tract by (Gln4)‐neurotensin. Infusion into the portal vein elicited the same vasoconstriction in adipose tissue as the same dose administered i.v. It is suggested that the vasoconstrictor action in adipose tissue is not caused by (Gln4)‐neurotensin per se. Instead, vasoactive substance(s) may be formed from (Gln4)‐neurotensin.