bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parallel Activation of Dynamic Fusimotor Neurones and a Climbing Fibre System from the Cat Brain Stem. I. Effects from the Rubral Region
Authors: Jeneskog Torgny 
Published: December 2008

AbstractClimbing fibre activity in the cerebellar paramedian lobule as well as hind limb dynamic fusimotor activation, caused by electrical stimulation in the rubral region, were studied in halothane anesthetized cats. A dorsal stimulating region, which was somatotopically arranged, could evoke climbing fibre activity in 3 longitudinal projection areas. This stimulating region was situated in the dorsal parts of the red nucleus and at caudal levels also dorsally to this structure. It was suggested that a synapse was interposed in this descending pathway at rostral rubral levels. From a ventral region, situated in the ventral parts of, but also extending ventrally and caudally to the red nucleus, only a hind limb projection area could be activated. The two pathways relay through the inferior olive and share olivary climbing fibres with each other and with ascending spino‐olivocerebellar paths. A marked similarity in the extent of stimulating areas activating hind limb dynamic fusimotor neurones and climbing fibres to one hind limb zone is demonstrated, as well as a close similarity in minimum stimulating thresholds for the two effects. The results are discussed in relation to a current hypothesis on the role of climbing fibre systems in motor control.
Titratable Acid, Pco2, Bicarbonate and Ammonium Ions along the Rat Proximal Tubule
Authors: Karimark Bertil , Danielson Bo G. 
Published: December 2008

AbstractThe proximal tubule of cortical nephrons of male albino rats were studied. The intratubular pH was measured with antimony microelectrodes. The concentrations of bicarbonate ions, the ammonium ions and titratable acid were measured in the same free flow samples from single tubules, using a recently developed ultramicroanalytical system, which also permits the estimation of intratubular Pco2. The concentration of titratable acid, which is thought mainly to emanate from phosphate, was found to be constant, about 1 mM, along the proximal tubule. This is explained as a gradient limited transport process for phosphate as well as for hydrogen ions. The concentration of ammonium ions was found to be about 2 mM along the convoluted proximal tubule in spite of water reabsorption, indicating some reabsorptive mechanisms for ammonium or the base, ammonia. Furthermore the present investigation indicates a high Pco2 in the untreated proximal tubule which could explain the phenomenon of disequilibrium pH.
Long‐term Treatment with Antihypertensive Drugs in Spontaneously Hypertensive Rats (SHR). Effects on Blood Pressure, Survival Rate and Cardiovascular Design
Authors: Weiss Lilian 
Published: December 2008

AbstractThree age groups of SHR were treated orally with hydralazine and guanethidine. The first “prehypertensive” group was treated from 2.5 until 8 months of age, and thereafter pressure was followed for another 6 months. A delayed and quite modest pressure increase then occurred and average life span was prolonged compared with untreated SHR or SHR treated only from 12 months of age. ‐ The second, 8 months old group, representing “established” hypertension, was treated for 5, 10 or 20 weeks, the last subgroup being followed for another 2 weeks without treatment. Arterial pressure, left ventricular weight and design of the resistance vessels as explored by quantitative hemodynamic analyses, were studied at these intervals. After 5 weeks pressure was normalized with some regression of hypertrophic vascular changes, particularly in females, though the increased wall/lumen ratio appeared to remain and heart weight was only slightly reduced. After 20 weeks with and 2 weeks without treatment, cardiac and vascular design were still the same as during treatment but pressure had now risen considerably. ‐ The third, 14 months old group with “advanced” hypertension was treated for 13 weeks, causing only modest pressure reduction and vascular regression. ‐ This suggests that early treatment has great advantages, that females exhibit more regression of vascular structural changes than males and that late treatment gives less regression, presumably due to addition of less reversible wall components like collagen.
Effects of Barbiturates on Synthesis and Rapid Axonal Transport of Protein in vitro in the Sciatic System of the Frog
Authors: Edstrom Anders , Larsson Håkan 
Published: December 2008

AbstractThe effects of hexobarbital, pentobarbital, methohexital and thiopental (0.5 mil and 2 mM) on the synthesis and fast axonal transport of 3H‐leucine‐labeIled proteins were studied in vitro in the sciatic system of the frog. The methodology used made it possible to discriminate between effects on synthesis and transport. All 4 drugs arrested the transport, pentobarbital being the most, and thiopental the least, potent one. The transport inhibiting effect of 0.5 mil pentobarbital was reversible but not that of the higher concentration. These drugs, at concentrations (2 mM) which inhibited axonal transport, did not influence the uptake of 3H‐leucine into ganglionic cell bodies, whereas pentobarbital, methohexital and thiopental, but not hexobarbital, depressed subsequent steps of protein synthesis. Pentobarbital lacked effect on protein synthesis at a concentration (0.5 mM), which arrested axonal transport by 50%. The results indicate that rapid axonal transport shows higher sensitivity than protein synthesis to the barbiturates tested. Fairly high concentrations of barbiturates were required to inhibit axonal transport and still higher to depress protein synthesis in the present study. Normal anesthesia by barbiturates is therefore hardly likely to affect these mechanisms.
Electrical Activity and Isometric Tension in Motor Units of the Cat's Inferior Oblique Muscle
Authors: L.Ennerstrand Gunnar 
Published: December 2008

AbstractSingle motor units of the cat's inferior oblique muscle were isolated by partial denervation of the muscle and threshold stimulation of split motor nerve filaments. With electrical tests singly innervated (SI) units, multiply innervated conducting (MIC) units and multiply innervated non‐conducting (MIXC) units could be differentiated. SI units conducted impulse activity faster (2.93 m/s) than MIC units (1.72 m/s). Singly innervated units contracted faster than multiply innervated units. Fusion frequency was found the most useful parameter for a mechanical separation; most SI units fused above 200 pps, most MIC units between 100 and 200 pps and the MIXC units below 100 pps. Tetanic tension was higher in fast (SI) than in slow (MIC and MIXC) units, but there was a considerable overlap. The range for the whole material was 25–425 mg. In fast units fusion fequency and the rate of stimulation for maximal tetanic tension coincided. In slow units maximal tetanic tension was reached at stimulus rates of 150–200 pps irrespective of the fusion frequency of the unit. Resistance to fatigue was high in the slow units and in the majority of the fast units.The contractile properties fit into the motor unit activity pattern determined through motoneuron recordings in alert animals.
Maximal Work Performance at Raised Air and Helium‐Oxygen Pressures
Authors: Fagraeus By Lennart 
Published: December 2008

AbstractTo study the influence of increased air pressure and gas density on maximal work performance, cardiorespiratory measurements were made on 8 subjects who performed maximal exercise until exhaustion on a cycle ergometer while breathing air at ambient pressures of 1.0 (control), 3.0, and 6.0 ATA, and a mixture of 79 % helium and 21 % oxygen (He‐O2) at 3.0 ATA (same density as air at 1.0 ATA). Exposure to air at 3.0 and 6.0 ATA caused no consistent changes in maximal oxygen uptake (Vo2max), peak blood lactate (LA), or endurance time, whereas pulmonary ventilation (VE) and carbon dioxide elimination (Vco2) decreased significantly with a consequent rise of end‐tidal PCo2 from 35 mm Hg at 1.0 ATA, to 56 mm Hg at 6.0 ATA. Maximal heart rate (HRmax) decreased from a mean control value of 192 beats‐min‐1to 183 beats‐min‐1at 6.0 ATA. With exposure to He‐O2 at 3.0 ATA, as compared to control, Vo2max and endurance time increased by 13 % and 14 %, respectively, whereas VE and HRmax decreased, Vco2 and LA remained unchanged, and end‐tidal Pco2 rose to 39 mm Hg. It is concluded that the beneficial effect that hyperoxia exerts on Vo2max and endurance time at normal gas density is offset when the gas density is high enough to cause ventilatory impairment with concomitant CO2 retention. The results also suggest that maximal work performance was more closely related to the LA concentration than to the Pco2 or pH levels existing in the working muscles at the point of exhaustion.
Metabolic State and Blood Flow in Rat Cerebral Cortex, Cerebellum and Brainstem in Hypoxic Hypoxia
Authors: Magmillan V. , Salford L. G. , Siesjö B. K. 
Published: December 2008

AbstractIn order to study the effect of hypoxic hypoxia upon regional cerebral metabolism and blood flow the arterial Poa of lightly anaesthetized rats was lowered to about 35, 29 and 23 mm Hg, respectively, with subsequent measurements of labile metabolites and of blood flow in cerebral cortex, cerebellum and brain stem. The metabolites, which included organic phosphates, carbohydrate substrates and amino acids, were measured with enzymatic, fluorometric techniques after freezing the tissue in situ and the regional blood flow was estimated from the tissue uptake of 14C‐ethanol. In all 3 regions marked hypoxia (Poa 23) gave rise to small increases in the ADP concentration, but since neither ATP nor AMP was changed from the normal it is concluded that the energy state remained essentially unaltered. The increase in lactate concentration was similar in all three regions and the substrate patterns were essentially the same. Since the regional blood flow also increased to a similar extent in the three regions it is concluded that brain regions show similar metabolic and circulatory changes in hypoxic hypoxia. The results thus give no support to the view that different brain areas show selective vulnerability to hypoxia, at least not in forms of hypoxia that are uncomplicated by absolute or relative ischemia.
Intrarenal Filtrate Distribution, during Saline Infusion in Rats with Unilateral Ureteral Ligation
Authors: Clausen G. 
Published: December 2008

AbstractSix days after unilateral ureteral ligation (UL) the contralateral kidney had increased GFR by 66 % in conscious rats. The average relative single nephron filtration rate (gfr) of superficial nephrons, as measured by the 14C ferrocyanide single injection technique, was 75 % of deep nephron gfr in UL rats compared to 90 % in intact rats. Thus hyperfiltration was more pronounced in deep nephrons. Isotonic saline infused i.v. (15 % BW in 60 min) in a second group of UL rats increased GFR by average 36 % compared to preinfusion GFR. Higher single nephron GFR and lower fractional sodium reabsorption enabled the UL rats to excrete sodium and water at practically the same absolute rates as compared to intact rats previously studied during identical saline infusion experiments. Saline infusion increased superficial gfr in UL rats from 75 % to 96 % of deep gfr. Provided superficial nephrons constitute 70 % of total nephron number these results imply that filtration rate rose by 48 % in superficial and by 16 % in deep nephrons. It is suggested that maximally one third of total sodium excretion in the saline infused UL rats might be due to superficial nephrons not being able to reabsorb their disproportionately increased filtered load.
Role of Tissue Hyperosmolality in Functional Vasodilatation in the Submandibular Gland
Authors: Lundvall By J. , Holmberg J. 
Published: December 2008

AbstractParasympathetic activation of the submandibular gland in the cat was found to cause considerable regional tissue hyperosmolality concomitant with the functional hyperemia response. The hyperosmolality, as traced in the venous effluent, was present at all rates of chorda nerve stimulation (0.25‐20 Hz). Osmolality was clearly raised already during the initial phase of the dilator response and reached plateau values during the later, steady state hyperemia response. In the latter phase it could exceed the resting control level by as much as 50 mOsm/kg H2O. There was a direct relation between the degree of venous hyperosmolality and the dilator response during low and moderate rates of chorda stimulation. Experimental hyperosmolality in die resting gland, produced by intra‐arterial infusion of hypertonic solutions, evoked a pattern of dilator response resembling that observed during chorda stimulation. Graded experimental hyperosmolality of magnitudes similar to those seen during chorda stimulation evoked progressively increasing dilatations of the resistance vessels. Comparison of the dilator effects during chorda stimulation and during hypertonic infusion at comparable levels of venous hyperosmolality indicated that tissue hyperosmolality contributed significantly to both the initial and maintained functional hyperemia response in the gland. The factor seemed to be of special importance at low and moderate rates of chorda excitation. This conclusion was supported by a separate series of experiments in which the effects of atropine on the functional hyperemia response and on the hyperosmolality were studied.
In Vitro Release of Corticosteroids from Adrenal Glands of Obese‐Hyperglycemic Mice (Gene Symbol ob)
Authors: Naeser By Peter 
Published: December 2008

AbstractThe adrenal function of obese‐hyperglycemic mice of various ages was investigated by measurements of the corticosteroid release from hemisectioned adrenal glands incubated in vitro. Glands from lean litter mates were used as controls. The corticosteroid release was strongly stimulated by ACTH and this stimulated release remained constant throughout the experiments. The ACTH effect was blocked when nitrogen was substituted for oxygen in the gas phase. In all investigated age groups the adrenals of obese mice displayed a higher release of corticosteroids than those of the lean controls when incubated without addition of ACTH. In the presence of ACTH the adrenal halves of obese mice showed a similar release of corticosteroids to those of the lean mice, except for the 2‐month‐old group, in which there was a smaller release from the adrenals of the obese animals. Insulin had no stimulating effect on the corticosteroid release and was even slightly inhibitory in the absence of ACTH in the medium. It is suggested that the increased size and steroid production of the adrenal glands of the obese‐hyperglycemic mice may reflect a continuous functional stimulation such as could be exerted by ACTH.
Bile Acids as Inhibitors of the Liver‐like Anion Transport System in the Rabbit Kidney, Uvea and Choroid Plexus
Authors: Bárány By Ernst H. 
Published: December 2008

AbstractSlices of rabbit kidney cortex, pieces of lateral choroid plexus and of ciliary body with iris were incubated in a potassium‐rich medium containing iodipamide and o‐iodohippurate labelled with different isotopes as test substances for the L‐and the H‐system respectively. Cholic, deoxycholic, chenodeoxycholic, lithocholic and dehydrocholic acids and their glycine and taurine conjugates were added as inhibitors and their ability to suppress iodipamide uptake preferentially compared. The most selective inhibitor was free chenodeoxycholic acid, followed by deoxycholic. Considerable inhibition was caused at 100, μM by the dihydroxy acids. At this concentration uptake of quaternary cations as “toxicity indicators” was hardly affected. Non‐ionic detergents were unselective inhibitors. Thus, bile acids have affinity for the liverlike anion transport system in the kidney, eye and choroid plexus.
Composite Transport Systems for Iodipamide and Iodohippurate out of the Cerebrospinal Fluid in the Rat
Authors: Lundberg By Viveka 
Published: December 2008

AbstractThe mechanism for the removal of iodohippurate and iodipamide from the CSF in rats was studied by ventriculo‐cisternal perfusion and by uptake experiments with choroid plexusin vitro. In agreement with finclings in other species excised plexus from the lateral ventricles accumulates131I‐o‐iodohippurate and125I‐iodipamide, and the process is at least partly saturable. Ventriculo‐cisternal perfusions were performed on pentobarbital anesthetized rats with a fluid containing131I‐o‐iodohippurate,125I‐iodipamide and14C‐inulin. A considerable loss of iodohippurate and iodipamide, but not of inulin, from the CSF was observed during the perfusion. When sodium hippurate and/or non‐labelled iodipamide were added in excess to the infusion fluid the loss of labelled iodohippurate and iodipamide was reduced. In concentrations which reduced iodohippurate loss equally, hippurate and iodipamide had different effects on iodipamide loss: hippurate had less effect. This indicates that iodohippurate and iodipamide are removed from the CSF partly by saturable and presumably active transport, and that iodipamide is transported both by the same system as iodohippurate and also by a separate hippurate‐insensitive one. Choroid plexus can be one locus of this transport.
Effects of Ethanol on Urine Sodium and Potassium Concentrations and Osmolality in Water‐Loaded Rats
Authors: Linkola By Jaakko 
Published: December 2008

AbstractThe effects of ethanol on urine sodium, potassium and osmolality were investigated in rats kept in a positive water balance produced by prior consecutive water loaclings. Ethanol loacling was followed by rapid rises in urine output, sodium concentration and osmolality and a somewhat slower rise in potassium concentration. Presumably water loacling led to an increased glomerular filtration rate, which, with the inhibition of ion reabsorption caused by ethanol, was responsible for this rise.
Motor and Secretory Effects of Autonomic Nerves and Drugs in the Rat Submaxillary Gland
Authors: Thulin By Anders 
Published: December 2008

AbstractThe effect of autonomic nerves and drugs on duct pressure and salivary flow was investigated in rat submaxillary gland. The results showed that it is possible to separate motor responses, probably exerted by activation of myoepithelial cells, from secretion. It is concluded that both divisions of the autonomic nervous system evoke motor responses and that the sympathetic motor effect is mediated via α‐receptors.
Effects of Sympathetic Stimulation on Facial Muscle Contractions
Authors: Lindquist Christer 
Published: December 2008

AbstractLow‐frequency stimulation (1–10 Hz) of the cervical sympathetic nerve is shown to increase twitch tension in the non‐fatigued orbicularis oculi and oris muscles by up to 15 % and to increase contraction and half‐relaxation times. The effect sets in 15–45 s following start of sympathetic stimulation, reaches a peak in 50–100 s and outlasts the stimulation by up to 90 s. The potentiating effect is not accompanied by any signs of changes in neuromuscular transmission or conduction. It is blocked by the /ff‐blocker propranolol. The mechanism of sympathetic action is discussed as well as its possible physiological significance.The possible presence of non‐twitch fibers of the slow tonic type in facial muscles is tested by i.v. injections of suxamethonium and decamethonium. Even relatively small doses not affecting neuromuscular transmission may produce long‐lasting contractions in the orbicularis oculi and oris. It is concluded that these contractions suggest specific properties of the twitch fibers rather than pointing to the presence of slow tonic muscle fibers.
Synthesis of Serum Albumin in Isolated Rat Liver Perfused by a Synthetic Medium with Fluorocarbon FG–80 Emulsion as Oxygen Carrier
Authors: Nováková Vera , Birke G. , Plantin L.‐O. 
Published: December 2008

AbstractA fluorocarbon emulsion FC‐80 has been used as a substitute for erythrocytes in a synthetic nutrition medium in in vitro perfusions of isolated rat livers. The rate of albumin synthesis was estimated. After the first hour albumin was synthesised at a constant rate of 0.52 + 0.17 mg/h per 100 g of the body weight of the liver donor. 14C‐lysine was incorporated into the circulating proteins linearly after the first hour. Other parameters tested were: levels of circulating proteins, urea nitrogen, glucose, glutamic‐pyruvic transaminase, excretion of bile, weight changes of the liver, and level of glycogen in liver tissue after perfusion. Histological examinations were also performed. The function of the liver was comparable with the findings of other investigators who used whole blood as the perfusate. As far as we are aware this is the first time that a rat liver has been maintained in good functional condition for over 6 hours during in vitro perfusions with a synthetic medium that included an erythrocyte substitute. The method seems to offer great advantages for the study of metabolic processes.
Single Unit Sympathetic Activity in Human Skin Nerves during Rest and Various Manoeuvres
Authors: Hallin Rolf G. , Torebjork H. Erik 
Published: December 2008

AbstractSingle unit activity in sympathetic nerve fibres was studied in microelectrode recordings from intact cutaneous nerves in alert man. 4 units exhibited a “spontaneous” discharge of very low frequency (not exceeding 15 imp/min) during resting conditions, whereas 4 other units were silent. Mental concentration and arousal stimuli of different types caused an increase in impulse frequency of spontaneously active units, and previously silent units started firing. In reflex responses to electrical shocks, deep breathing and loud noises, single units often fired repeatedly in bursts, the maximal instantaneous frequency observed being 35 imp/s. Intense reflex responses to electrical stimulation were sometimes followed by a suppression of spontaneous activity for 1–2 s. Some of the units probably had a sudomotor function, since the unit activity correlated well with changes in galvanic skin resistance recorded within the innervation zone of the explored nerve fascicle. The conduction velocity measured for 6 sympathetic units ranged 1.0–0.58 m/s.
Methods to Differentiate Electrically Induced Afferent and Sympathetic C Unit Responses in Human Cutaneous Nerves
Authors: Hallin Rolf G. , Torebjörk H. Erik 
Published: December 2008

AbstractC unit responses to intradermal electrical stimulation were recorded with tungsten micro‐electrodes inserted percutaneously into intact human cutaneous nerves. An increase in discharge frequency was associated with a decrease in conduction velocity in unmyelinated fibres, and this phenomenon was used to identify afferent C units which responded to both electrical and natural stimuli in the skin. Antidromic impulses in efferent, sympathetic fibres were also elicited by electrical stimulation in the skin as judged by latency changes or signs of collisions in the C responses associated with activity in sympathetic fibres. In this way, conduction velocities in distal segments of both afferent and sympathetic C fibres can be estimated. Furthermore, the possibility to differentiate afferent and sympathetic C units is of obvious importance for the study of their respective discharge characteristics and in psychophysiological studies in alert man.
Effect of 2, 3‐Diphosphoglycerate on the Oxygen Affinity and on the Proton‐ and Carbamino‐Linked Oxygen Affinity of Hemoglobin in Human Whole Blood
Authors: Arturson G. , Garby L. , Wranne B. , Zaar B. 
Published: December 2008

AbstractOxygen binding curves were determined, at two plasma pH values in the range 7.0–7.5, each at two pCOa values of 22 and 77 mm Hg, respectively, on human whole blood where the red cell 2,3‐diphosphoglycerate (DPG) concentration had been decreased to about 1 mmol/1 of packed cells and increased to about 9 mmol/1 of packed cells. Numerical values are given for the oxygen‐saturation‐dependant ligand interaction coefficients AlogpOzl ApH, AiogpOzl/llog/>C02 and /llog/)02//llogDPG and their dependance on pH, PCO2 and DPG, respectively.