bluuebunny/crossref_metadata_2025 huggingface dataset:
Intracellular Ca2+ buffering potentiates an 86Rb+ permeability response in human lymphocytes
Authors: HEIKKILÄ R. , IVERSEN J.‐G. , SMELAND ERLEND , GODAL TORE
Published: December 2008

The effects of antibodies against immunoglobulin δ‐heavy chains (anti‐δ) on intracellular free Ca2+ concentrations, [Ca2+]i, and 86Rb+ influx in human neoplastic B‐cells were tested in vitro. When preloading the cells with high concentrations of the fluorescent Ca2+ chelator quin 2 and subsequently stimulating in EGTA medium, the anti‐δ induced rise in [Ca2+]i was strongly reduced or blocked. Nevertheless, 86Rb+ influx, also induced by anti‐β, was potentiated. In fact, in a population of cells in which anti‐δ increased [Ca2+]i, but not 86Rb+ influx under standard conditions, the combination of quin‐2 preloading and subsequent extracellular Ca2+ chelation by EGTA revealed an anti‐δ induced 86Rb+ influx. Most of this influx was ouabain resistant, suggesting only a minor contribution from the Na+/K+ pump. Based on the Ca2+ buffer effect of quin 2 we suggest that the Ca2+ effect on 86Rb+ (K+ analogue) permeability is not mediated by increased [Ca2+]i but rather by the Ca2+ release per se from the plasma membrane.
Afferent vagal control of fluid absorption in the feline jejunum
Authors: SJÖVALL HENRIK
Published: December 2008

The aim of the study was to test experimentally whether vagal afferent pathways are involved in the reflex regulation of jejunal fluid absorption. Acute bilateral cervical vagotomy led to an increase in net jejunal fluid absorption rate, an effect which was abolished by previous division of the splanchnic nerves. Selective division of the right cardiac branch of the vagal nerve induced an increase in fluid absorption similar to that elicited by truncal cervical vagotomy. Afferent stimulation of the right cardiac nerve at frequencies within the physiological firing range for unmyelinated C‐fibre afferents induced an inhibition of net fluid absorption. Based on these findings, we propose a reflex pathway containing a non‐myelinated vagal afferent branch originating from cardiopulmonary receptor endings, and an efferent sympathetic branch reaching the jejunum via the splanchnic nerves. Such a pathway might be of physiological importance in extracellular volume control by regulating the rate of fluid transport across the intestinal mucosa.
Effect of varying exercise intensity on glycogen depletion in human muscle fibres
Authors: VØLLESTAD NINA KØPKE , BLOM PER C S.
Published: December 2008

VØLLESTAD, N.K. & BLOM P.C.S. 1985. Effect of varying exercise intensity on glycogen depletion in human muscle fibres. Acta Physiol Scand125, 395–405. Received 15 December 1984, accepted 30 April 1985. ISSN 0001–6772. Institute of Muscle Physiology, Oslo, Norway.

Glycogen depletion of muscle fibre types I, II A, IIAB and IIB was studied during bicycle exercise at 43% (π= 5), 61% (π= 7) and 91% (π= 5) of Vo2 max Glycogen content in individual fibres from vastus lateralis muscles was quantified as optical density of periodic acid‐Schiff (PAS) stain. After 60 min at the lowest intensity, glycogen depletion was observed in almost all type I fibres and in about 20% of type IIA fibres. After 60 min exercise at 61 % of Vo2max, glycogen breakdown was observed in all type I fibres and in about 65% of type IIA fibres. During the first part of exercise at 91% of Vo2 max, glycogen breakdown was observed in all type I and IIA and in about 50% of type IIAB and IIB fibres. Muscle lactate concentration increased during the first 5 min of exercise at 91% of Vo2max to 15 mmol kg‐1 (w/w) and remained thereafter at this level. From start of exercise the average rates of glycogen depletion in type I fibres were about 1.0,2.0 and 4.3 mmol glucosyl units kg‐1 (w/w) min‐1 at 43%, 61 % and 91 % of Vo2max The depletion rates were almost constant with time at the two lower intensities. The results indicate that the number of fibres activated from the start increase gradually in response to increased exercise intensity. The rates of glycogen depletion in type I fibres suggest a progressive tension output of these fibres with increasing intensity.
The control of granule movement in fish melanophores
Authors: GRUNDSTRÖM N. , KARLSSON J. O. G. , ANDERSSON R. G. G.
Published: December 2008

GRUNDSTRÖM, N., KARLSSON, J.O.G. & ANDERSSON, R.G.G. 1985. The control of granule movement in fish melanophores. Acta Physiol Scand125, 415–421. Received 4 December 1984, accepted 8 May 1985. ISSN 0001–6772. Departments of Pharmacology and Biology, Linkoping University, Sweden.

The effects of electrical field stimulation, alpha‐2‐adrenoceptor activation and manipulation of the intracellular machinery on aggregation and dispersion of melanosomes within melanophores of Labrus ossifagus were studied. Neither melatonin nor MSH exerted any direct effects on the melanophores, and furthermore MSH alone did not affect the responses elicited by electrical stimulation or by noradrenaline. Omitting extracellular Ca2+ blocked the nerve‐mediated aggregation but was without effect on noradrenaline‐induced aggregation. Colchicine and demecolcine inhibited the melano‐some aggregation induced by noradrenaline. The characteristics of aggregation and dispersion were found to diverge in several ways. In melanophores made permeable by using saponin, cyclic AMP caused dispersion. The dynein‐ATP‐ase inhibitor vanadate prevented the melanosome aggregation within saponin‐treated melanophores, while vandate was without effect on the cyclic AMP‐induced dispersion. The melanosome transport in saponin‐treated melanophores could be activated even in the absence of Ca2+, indicating that the melanosome movements were completely Ca2+‐independent.
Endothelial negative surface charge areas and blood‐brain barrier function
Authors: HARDEBO J. E. , KÅHRSTRÖM J.
Published: December 2008

HARDEBO, J.E. & KÅHRSTRÖM, J. 1985. Endothelial negative surface charge areas and blood‐brain barrier function. Acta Physiol Scand 125, 495–499. Received 30 January 1984, revised 26 March, 1985. ISSN 0001–6772. Departments of Histology and Neurology, University of Lund, Sweden.

Recent evidence points to the negative surface charge of the luminal endothelial membrane of brain vessels as one determinant for morphologic blood‐brain barrier function. The present study evaluates, in awake rats, how barrier function is affected by the polycation protamine to neutralize the negatively charged groups. High local doses of protamine, as infused intracarotideally, are able to substantially impair barrier capacity against albumin and inulin, which normally do not pass the blood‐brain barrier. Evidence is presented that it is the positive charge of protamine that is a major factor underlying the barrier opening. However, when comparing the barrier opening obtained by corresponding concentration of the polycation lysine, it was obvious that another property of protamine contributed. This property was not linked to hyperosmolar, hypertensive or vasodilatory barrier opening, but may be a direct, cytotoxic effect of protamine. It is discussed whether barrier opening through transendothelial vesicular or channel transport occurs only at locations on the cell membrane deprived of negative surface charge areas.
Lymphatic drainage from subcutaneous tissue in the foot and leg in the sitting human
Authors: ASA M. , SKRETTING A. , ENGESET A. , WESTGAARD R. , NICOLAYSEN G.
Published: December 2008

AAS, M., SKRETTING, A., ENGESET, A., WESTGAARD, R., NICOLA YSEN, G. 1985. Lymphatic drainage from subcutaneous tissue in the foot and leg in the sitting human. Acta Physiol Scand 125, 505–511. Received 27 March 1985, accepted 22 May 1985. ISSN 001–6772. The Norwegian Radium Hospital, Montebello 0310, Oslo 3, Norway, Institute of Work Physiology, Oslo and Institute of Physiology, University of Oslo.

To determine how fast lymph is drained from the foot in the sitting, completely relaxed position, we injected 99mTc‐labelled human serum albumin subcutaneously between the first and second toe of both feet in three subjects sitting with legs down. Radioactivity appeared in the calf within the first 30 s, in the thigh within 1 min and in the blood between 2 and 5 min after injection. A scintigram of the calves showed distinct strands of activity. Radioactivity was found in the inguinal lymph nodes and in no other lymph nodes. The radioactivity in the segments of the calf showed rhythmic variations. EMGs showed minimal muscular activity during the examination. We conclude that interstitial fluid is drained by way of the lymphatics against gravity and most probably as a result of the intrinsic contractions of the lymphatics.
Inhibition of shivering in man by thermal stimulation of the facial area
Authors: MEKJAVIC I. B. , EIKEN O.
Published: December 2008

MEKJAVIC, I. B. & EIKEN, O. 1985. Inhibition of shivering in man by thermal stimulation of the facial area. Acta Physiol Scand 125, 633–637. Received 26 April 1985, accepted 28 May 1985. ISSN 0001–6772. Department of Kinesiology, Simon Fraser University, Burnaby, Canada, and Department of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden

The contribution of the facial thermoreceptors to thermoregulatory shivering was studied. Seven subjects were exposed to – 3 °C ambient air for 1 h. Radiant heat was applied to the facial area during 30 s periods at 10 min intervals and the effects on the integrated electromyographic activity (IEMG) in the brachial biceps, trapezius and femoral rectus muscles, and on the heart rate (HR) were studied. During cold‐air exposure mean skin temperature as measured at four sites decreased by 15.5±0.6 °C (mean ± SE) while rectal temperature remained virtually unchanged. During the radiant heat exposures IEMG activity decreased by 18.9 ± 2.3%; HR decreased by 11± 1 beats min‐1. The changes in IEMG occurred within or slightly below the range of maximum cold receptor sensitivity (20–30 °C) and coincided with the maximum rate of change in chin temperature. The observed inhibition of shivering IEMG during locally applied facial heat stimulation suggest that the trigeminal region contributes an important input to the overall thermoregulatory responses.
Neuromodulation by adenine nucleotides, as indicated by experiments with inhibitors of nucleotide inactivation
Authors: WIKLUND N. PETER , GUSTAFSSON LARS E.
Published: December 2008

The adenine nucleotides AMP, ADP and ATP (3 × 10‐7M AND above) inhibited contractile responses to transmural nerve stimulation in guinea‐pig ileum longitudinal muscle via a prejunctional action. Nucleotides assumed to inhibit the degradation of adenine nucleotides were employed to determine whether inhibition of contractile responses was elicited by adenine nucleotidesper se, or required breakdown to adenosine.

The IMP or 2′‐deoxy AMP enhanced the prejunctional inhibitory effect elicited by AMP. A similar enhancementofthe inhibitory effect of ADP and ATP was seen after administration of IDP and ITP, respectively. The inhibitory effect of adenosine was not enhanced by inosine, IMP or IDP.

The 5′‐nucleotidase inhibitor, TDP enhanced inhibition elicited by ADP. In contrast, α, β‐meADP did not influence the prejunctional inhibitory effect elicited by the adenine nucleotides. However, the combination of α, β‐meADP and IMP enhanced the inhibitory effect of ATP. The postjunctional contractile effect elicited by ADP and ATP was enhanced by pretreatment with inosine nucleotides, α,β‐meADP or TDP, indicating decreased inactivation of ADP and ATP during concurrent nucleotide administration. The fact that the prejunctional effect of adenine nucleotides can be enhanced by forms of pretreatment known to antagonize the breakdown of adenine nucleotides, constitutes strong evidence for prejunctional actionper seby adenine nucleotides.
The influence of renal papillary urea concentrations and of plasma vasopressin on the urinary prostaglandins E2and F2αexcretion in conscious rats in steady state of urine formation
Authors: BOJESEN EIGIL , BOJESEN INGE N.
Published: December 2008

Urinary excretion rates of PGE2and PGF2αwere measured radioimmunologically in four different groups of unanaesthetized rats: water diuretic rats (I), rats with free access to water (II), water deprived rats (III) and 1.5% saline‐loaded rats (IV). The animals were decapitated when steady states of urine formation were ascertained for three to six spontaneously delivered urine portions. Plasma vasopressin was measured radioimmunologically and urea, sodium, potassium concentrations and osmolalities of papillary fluids and of bladder urines were determined. Group means of urinary prostaglandin excretion, papillary urea concentration and logarithmic‐transformed plasma vasopressin values vary in parallel for three of the groups (I, II and III) but a dissociation of the effects of papillary urea and vasopressin on the prostaglandin excretion was obtained for group IV. Statistical analyses indicated that the differences in prostaglandin excretion rates between group I and the three other groups are accounted for by the combined effects of vasopressin and papillary urea. The results support the hypothesis that vasopressin stimulates release of arachidonic acid in the papilla and that urea inhibits the trapping of this prostaglandin precursor in cellular lipids. The ratio of urinary PGF2αto PGE2varied greatly between groups but no consistent dependency on the measured parameters was found.
A study of proximal tubular compliances in normotensive and spontaneously hypertensive rats, and the effect of anaesthesia on the compliance
Authors: LEYSSAC P. P. , JENSEN P. K. , HOLSTEIN‐RATHLOU N.‐H.
Published: December 2008

Proximal tubular compliance (C) was measured in free flow microperfusion experiments from the initial slope of the increase in proximal luminal pressure divided by the step input of volume flow delivered from a microperfusion pipette inserted in a downstream proximal convolution. Five groups of rats were studied: Munich Wistar (WU, n = 11) and Sprague‐Dawley rats (SPRD, n = 6) anaesthetized with inactin; and SPRD (n = 11), Wistar Kyoto (WKY, n = 9), and sponaneously hypertensive rats (SHR, n = 11) anaesthetized with halothane. In the inactin groups, C was: 0.309 ± 0.161 and 0.266 ± 0.136 nl mm Hg‐1, respectively. In the halothane groups, C was: 0.125 ± 0.023, 0.125 ± 0.029, and 0.119 ± 0.0127 nl mm Hg‐1, respectively. The means in the inactin groups were significantly higher than those from the halothane groups (P < 0.001). It is concluded that the choice of anaesthetics has a profound influence on the proximal tubular compliance in the rat, and that the compliance of SHR is equal to that of normotensive rats.
Effect of carotid artery occlusion and ganglionic blockade on regional blood flows and intestinal damage after haemorrhagic hypotension in the rat
Authors: GRÖGAARD B. , LUNDBERG K. , GERDIN B. , ARFORS K.‐E.
Published: December 2008

The effects of cerebral ischaemia by carotid artery occlusion and of a ganglionic blocking agent (Arfonad) on cardiac output and regional blood flows were studied after 15 min of haemorrhagic hypotension (mean arterial pressure 50 mmHg) in the rat. The microsphere technique was used for blood flow determinations. Animals subjected to haemorrhagic hypotension and simultaneous carotid artery occlusion (group BC) exhibited a stronger immediate vasoconstrictor response than animals subjected to haemorrhagic hypotension only (group B) and more blood had to be withdrawn to achieve stable hypotension at 50 mmHg (2.6 ± o. 1 vs. 2.2 ± 0.4 ml per 100 g body weight (body wt); P < 0.05). However, group B showed the same decrease in cardiac output as group BC, but the blood flows of the kidneys, spleen, intestine, liver and skin were less deranged at the end of the hypotensive period. Groups B and BC exhibited similar intestinal ischaemic mucosal damage, measured as leakage of [125I]albumin. When induction of haemorrhagic hypotension was combined with ganglionic blockade administration (Arfonad) and carotid artery occlusion (group ABC), significantly less blood had to be withdrawn than in groups BC (1.6 ± 0.2 vs. 2.6 ± 0.1 ml per 100 g body wt; P < 0.05). The blood flows of the kidneys, small intestine, liver, spleen and skin were less compromised in group ABC. In addition, group BC had more profound metabolic acidosis and were more haemoconcentrated than group ABC; moreover, group BC, tended to be hypoglycaemic and showed intestinal mucosal damage, whereas neither of these effects occurred in group ABC. It was concluded that carotid artery occlusion and cerebral ischaemia aggravated the circulatory effects of the haemorrhagic hypotension, and that ganglionic blockade on induction of the ischaemic period blunted such effects in the present model.
Measurement of respiratory water loss in newborn lambs
Authors: HAMMARLUND K. , RIESENFELD T. , SEDIN G.
Published: December 2008

A flow‐through system for measurement of respiratory water loss, providing data on oxygen consumption and carbon dioxide production, is described. The system uses a mass spectrometer, specially equipped with a water channel, for analysis of gas concentrations. To avoid condensation of water vapour, the tubing in the flow‐through system is heated. The method was tested by evaporating known amounts of water, and was found to be very accurate with a correlation coefficient of 0.999. Measurements were made in 10 fullterm lambs of varying postnatal age (4–15 days) and a mean respiratory water loss (RWL) of 11.7 mgkg‐1 min‐1 was found at rest. The RWL decreased with increasing postnatal age, as did oxygen consumption. The RWL at rest was influenced by the ambient relative humidity, with higher values at lower humidities.
Inhibition of fatty acid mobilization by arterial free fatty acid concentration
Authors: MADSEN J. , BÜLOW J. , NIELSEN N. E.
Published: December 2008

Subcutaneous, inguinal adipose tissue from dogs was perfused with blood in which the free fatty acid (FFA) concentration was varied corresponding to FFA/albumin molar ratios between 1 and 6. Otherwise the composition of the perfusate was kept constant. In order to stimulate lipolysis, isoprenaline and theophyllamine were added to the perfusate. A raise in arterial FFA/albumin molar ratio was without influence on lipolysis (as reflected in the release of glycerol), but reduced the FFA release indicating an increased re‐esterification. At FFA/albumin ratios above 3 a marked increase in vascular resistance was seen. This increase was partly reversible within the time of a perfusion. When lipolysis is stimulated in the intact organism, the effects of increasing arterial FFA/albumin ratio on re‐esterification and vascular resistance may serve as feedback mechanisms regulating FFA mobilization.
Potentiation of glucose‐induced insulin secretion in the perfused rat pancreas by porcine GIP (gastric inhibitory polypeptide), bovine GIP, and bovine GIP(139)
Authors: SANDBERG E. , AHRÉN B. , TENDLER D. , CARLQUIST M. , EFENDIC S.
Published: December 2008

Porcine GIP (gastric inhibitory polypeptide) potentiates glucose‐induced insulin secretion under a variety of experimental conditions. Recently GIP was isolated also from bovine intestine, and found to differ from porcine GIP by having isoleucine instead of lysine in position 37. We have compared the effects of porcine GIP to that of bovine GIP and bovine GIP(]_39) on glucose‐induced insulin secretion from the perfused rat pancreas. We found that porcine GIP, bovine GIP, and bovine GIP(l_39) all strongly potentiated both first and second phases of glucose‐induced insulin secretion (glucose concentration 6.7 mM; polypeptide concentration 1 nM). There was no significant difference between the polypeptides with regard to the potency to potentiate glucose‐induced insulin secretion. We conclude that bovine GIP, as porcine GIP, potentiates glucose‐induced insulin secretion, and that the insulinotropic activity of GIP is not confined to the last three amino acids at the C‐terminal end.,
Presynaptic inhibition of acetylcholine release
Authors: AAS P. , FONNUM F.
Published: December 2008

High potassium (51 HIM) has been shown to evoke release of acetylcholine ([3H]ACh and endogenous ACh) from cholinergic nerves in rat bronchial smooth muscle. The release of [3H]ACh was reduced by 85 % when the Ca2+ concentration was changed from 2 to 0.1 mM. The veratridine‐induced release was completely inhibited by tetrodotoxin, but tetrodotoxin did not reduce the potassium‐evoked release. The muscarinic agonist, oxotremorine, reduced the potassium stimulated release of [3H]ACh, without affecting the basal release. In contrast, scopolamine substantially potentiated the potassium‐evoked release. Adenosine had a dual effect in the rat bronchi. Adenosine inhibited the potassium‐evoked release of [3H]ACh and this presynaptic effect of adenosine was antagonized by 8‐phenyltheophylline. Adenosine also induced contraction of the bronchial smooth muscle and there was potentiation by adenosine of the ACh‐induced contraction. The results indicate that cholinergic nerve terminals in the rat bronchi possess muscarinic receptors which inhibit the release of ACh. Adenosine may have analogous effects, e.g. presynaptic inhibition of transmitter release in addition to postsynaptic enhancement of bronchial smooth muscle contraction.,
Increased CO2 drive for ventilation in healthy human subjects may interfere with their ability to control lung volumes voluntarily
Authors: KATZ‐SALAMON M.
Published: December 2008

Influence of increased CO2 drive for ventilation on the ability to judge lung volume was studied in seven healthy subjects. The psychophysical relationships between the objective and subjective magnitudes of lung volume were tested during air breathing and at two levels of hypercapnia (breathing 4% and 6% CO2 in oxygen). The relationships, described by linear regression, were analysed with respect to correlation coefficient, slope and intercept of the regression line. Slope and intercept seemed to decrease as the inspired CO2 mixture increased. Statistically significant difference was found only between air and inhalation of 6% CO2 in oxygen. Correlation coefficient remained unaffected by an increase in PCOr These results indicate that an experimental increase in PCO2 caused by 6% CO2 inhalation alters the behavioural respiratory control in healthy human subjects.,
Regional differences in evoked response latencies in the cat motor cortex (area 4γ)
Authors: ANDERSSON G.
Published: December 2008

The latencies of responses evoked in the cat motor cortex (area 4γ) on contralateral forelimb nerve stimulation were measured. In the caudolateral part, the latencies were 4^5 ms on ulnar and superficial radial nerve stimulation. Further, rostromedially the response latencies were longer, 7–9 ms. The latency‐to‐peak of the evoked responses was also measured and showed a parallel increase. In many cases, inflexions could be observed on the rising phase of the evoked potential, indicating that it consisted of several components. In most experiments, four components (HV) were observed. Their mean latencies were 4.3, 6.0, 7.2 and 8.5 ms, respectively. The early components were largest in the caudolateral part of area 4γ and decreased when recording further rostromedially such that, in the anterior sigmoid gyrus, usually only component IV could be recorded. The findings suggest that the cat motor cortex is functionally divided into regions which can be identified by their peripheral input latencies.,
Nicotinic effects on the firing pattern of midbrain dopamine neurons
Authors: GRENHOFF J. , ASTON‐JONES G. , SVENSSON T. H.
Published: December 2008

The effects of systemic administration of nicotine or the nicotinic antagonist mecamyl‐amine on the midbrain dopamine (DA) systems of the rat were studied with single cell recording techniques. Dopamine cells of the zona compacta, substantia nigra (ZC‐SN) and the ventral tegmental area (VTA) were identified by their characteristic action potentials, antidromic stimulation methodology and conventional histological procedures. Firing rates as well as firing patterns were determined from computer‐generated interspike interval histograms describing burst‐firing in relation to single‐spike firing. A larger proportion of burst‐firing DA cells was found in the VTA when compared with the ZC‐SN area. (–)‐Nicotine bitartrate (0.5 mg kg‐1 i.p.) not only increased the firing rate of ZC‐SN neurons but also the amount of burst firing of the ZC‐SN neurons and VTA neurons, respectively. Mecamylamine HC1 (4.0 mg kg‐1 i.p.) decreased the firing rate of VTA cells which, in principle, indicates a tonic nicotinic input in this area. The increase in firing rate of central DA neurons following nicotine administration was found to be associated with increased bursting of the burst firing cells whereas, in contrast, the non‐bursting neurons did not respond with burst‐firing. Generally, the correlation between nicotine induced changes in firing rate and in burst‐firing activity, respectively, was found to be low for midbrain DA neurons. These observations, in conjunction with the previous demonstration of nicotinic receptors in these areas, indicate the existence of a nicotinic input, specifically regulating the firing pattern of these central DA cells. This neuromodulatory effect of nicotine may be significant for its behavioural stimulant action. In addition, it could alter the ratio of release of coexisting neuronal messengers from midbrain DA neurons.
Observations on normal EEG activity in different brain regions of the unrestrained swine
Authors: FORSLID A. , ANDERSSON B. , JOHANSSON S.
Published: December 2008

This methodological and electrophysiological study was undertaken with the aim of obtaining possibilities for evaluating objectively the ethical value of using high concentration CO2 inhalation as pre‐slaughter anaesthesia for swine. A technique for implantation of recording electrodes into the porcine neocortex and limbic system is described, as are results of EEG recording from these brain regions in the unrestrained animal. In addition to expected desynchronized activity in the awake animal, bilateral recordings from the frontal neocortex revealed the irregular occurrence of ‘sleep spindles’ during apparent non‐REM sleep. The ‘spindles’ were sometimes unilateral, and when bilaterally simultaneous, the amplitude was often larger in one of the hemispheres. The EEG recorded from the dorsal hippocampus was characterized by theta‐wave activity. The offering of food to the hungry animal, and subsequent brief feeding periods, were associated with marked accentuation of this theta activity. Recording via electrodes placed within the amygdaloid nuclear complex showed high‐frequency activity irregularly interrupted by slow waves. However, if one of the ‘amygdaloid’ twin electrodes hit the ventral pole of the hippocampus, theta activity was dominant. Electrodes placed adjacent to the amygdaloid nuclei in the pyriform cortex exhibited a basic awake activity similar to that recorded from these nuclei. During apparent non‐REM sleep, however, trains of slow waves were seen simultaneously with the appearance of ‘sleep spindles’ in the ipsilateral neocortex.
Sodium appetite as well as 24‐h variations of fluid balance, mean arterial pressure and heart rate in spontaneously hypertensive (SHR) and normotensive (WKY) rats, when on various sodium diets
Authors: ELY D. E. , THORÉN P. , WIEGAND J. , FOLKOW B.
Published: December 2008

Young SHR and WKY rats were compared, first, concerning sodium (Na) appetite during ‘rest’, mild social stress and ACTH injections, second, concerning the diurnal patterns of water intake, urine output, mean arterial pressure (MAP) and heart rate (HR) while on various Na diets: 0.5 mmol Na (LNa), 5 or 12–13 mmol Na (CNa), 50 (HNa) or 120 mmol Na (vHNa) per 100 g food. Sodium appetite and water intake were about 50% higher in SHR than in WKY (4–4.5 vs 2.5–3 mmol Na per 100 g body wt day‐1)‐It was modestly increased by both social stress and ACTH, and more so in WKY, thereby approaching that in SHR. Concerning the various Na diets and their influences, daytime resting MAP was modestly lowered in LNaSHR and slightly increased in vHNaSHR compared with CNaSHR but largely equal in all WKY groups. Food‐water consumption was concentrated to the active night period, but even high Na‐water intakes caused no signs of sustained hypervolaemia, because each intake bout was in both SHR and WKY eliminated by urine within 30–40 min. However, particularly the vHNa diet in SHR also increased the frequency of drinking, and each bout caused transient, evidently neurogenic MAP and HR increases which occurred too rapidly to be consequences of blood volume expansion. As a result, the diurnal MAP‐HR patterns in SHR varied markedly with the Na diets, in vHNa group resulting in considerably raised average diurnal MAP levels even though resting daytime MAP was here nearly the same as in CNaSHR. These findings illustrate how largely continuous diurnal recordings are needed to judge correctly the relationships between, for example, Na intake, volume equilibrium and MAP. Finally, the relevance of these results in rats for also judging the control of Na balance in man is discussed.
Permeability of renal capillaries. I. Preparation of neutral and charged protein probes
Authors: ÖJTEG G. , NYGREN K. , WOLGAST M.
Published: December 2008

This paper describes the preparation of charged and uncharged protein molecular probes for study of the permselectivity of renal capillaries. Horse heart myoglobin was used as a neutral myoglobin. Since it contained several fractions with different isoelectric points, it was purified by fast protein liquid chromatography (FPLC). To obtain a negatively charged myoglobin, the original horse heart myoglobin was treated with cyanate, resulting in net charge of ‐5.7 ± 0.3 at physiological pH (mean ± SEM). The charge was determined from the Donnan potential which develops over a semipermeable membrane separating the inside solution in which the protein was dissolved from a surrounding bath of equal ionic strength. Sperm whale myoglobin was similarly purified by FPLC and used as a positively (+ 1.7 ± 0.2) charged isomer. Horseradish peroxidase (HRP) was purified by means of gel and ion‐exchange chromatography and found to be neutral at physiological pH. Negatively charged (‐14.0 ± 0.5) HRP was obtained by succinylation. Two isomers of lactate dehyrogenase (LDH) were used, namely the slightly positive (+ 2) LDH‐M4 and the strongly negative (‐19) LDH‐H4. These isomers, which occur naturally, did not require further purification. The Stokes‐Einstein radii, as measured by gel chromatography, of inulin, myoglobin, HRP and LDH were 11,17±5, 32 and 46 Å, respectively. The chemical modifications did not alter the Stokes‐Einstein radii. In biological studies on rat kidneys samples of both plasma and renal hilar lymph were found to contain radioactive low molecular weight degradation products in addition to the intact proteins. This necessitated separation of all individual samples on small Sephadex columns prior to analysis.
Effect of spontaneous running on blood pressure, heart rate and cardiac dimensions in developing and established spontaneous hypertension in rats
Authors: HOFFMANN P. , FRIBERG P. , ELY D. , THORÉN P.
Published: December 2008

The effect of chronic voluntary exercise on resting blood pressure and heart rate was measured in two different age groups of spontaneously hypertensive rats (SHR). In the younger group, left ventricular dimensions were also measured. The younger group was 9 weeks old at the start of the experiment and was in a period of rapid blood‐pressure rise. The older group, 13 weeks old at the start of the experiment, already had established hypertension. During a period of 6 weeks, the animals ran spontaneously in wheels mounted in their cages and reached a maximum of 6–7 km per 24 h. Age‐matched, sedentary SHR were used as controls. Both groups of runners showed a decrease in body weight in comparison to controls. The younger runners exhibited a delayed onset of hypertension. They also showed a significantly increased left ventricular (LV) end‐diastolic volume for every measured end‐diastolic pressure between 7.5 mmHg and 20 mmHg (P < 0.05). This suggests the development of a structural growth‐dependent increase of the internal LV radius while LV weight and wall‐to‐lumen ratio were largely unaltered in younger runners compared with controls. In SHR with established hypertension, physical training did not reduce arterial blood pressure but heart rate was significantly lower than in the controls. These results thus indicate that an early onset of physical exercise in SHR may delay the development of hypertension. In addition, a more favourable cardiac design could also be seen.
NADH content and lactate production in the perfused rabbit heart
Authors: KATZ A. , EDLUND A. , SAHLIN K.
Published: December 2008

The influence of oxygen availability and absence of contractile activity on the NADH content and lactate production were investigated in the rabbit heart. Isolated hearts were perfused according to Langendorff with a modified Tyrode solution, saturated with a gas mixture containing either 95% O2: 5% CO2 (control), 50% O2: 5% CO2 in N2 (hypoxia), or 5% CO2 in N, (anoxia). In another series of hearts cardiac arrest was induced by perfusion with Tyrode solution (95% O2: 5% CO2) where the KCl concentration was increased to 15 mmol 1‐1 (hyperkalemia). Oxygen uptake (VO2 was similar in hypoxic and control hearts (P > 0.05), whereas lactate production was four‐fold higher during hypoxia vs. control (P < 0.01). Hyperkalemia resulted in a 60% decrease in VO2(P < 0.05), and no significant change in lactate production vs. control (P > 0.05). Both PCr and ATP were substantially decreased only during anoxia. Muscle NADH, whose changes reflect those within the mitochondria, averaged (±SE;) 0.074 ± 0.010, 0.153 ±0.016, 0.486 ± 0.162 and 1.771 ± 0.091 mmol kg‐1 dry wt during control, hyperkalemia, hypoxia and anoxia, respectively. It is concluded that: (I) muscle contraction during conditions of adequate oxygen supply results in an oxidation of mitochondrial NADH (presumably due to ADP stimulation of respiration), and (2) a decreased oxygen availability results in an increase in NADH and an accelerated lactate production, although the VO2 is not affected.
The microsphere method for measuring low blood flows: theory and computer simulations applied to findings in the rat cochlea
Authors: HILLERDAL M. , SPERBER G. O. , BILL A.
Published: December 2008

When the microsphere method of blood flow measurement is used in small organs, the number of spheres actually recovered may be small. This introduces errors which, however, are not necessarily important as compared with the biological variation. A mathematical model was constructed which allowed estimation of the extra uncertainty caused by the low number of spheres. It was applied to an experimental material of over 100 measurements of cochlear blood flow in the rat, where only about 60 spheres were recovered per cochlea. It was concluded that this paucity of spheres introduced only a small to moderate extra error. Simple approximate formulae were derived allowing easy estimation of the uncertainty caused by low number of spheres under different conditions. In general, there appear to be many situations where fewer microspheres than are commonly used would suffice.
The effect of secretin on the glucose‐induced insulin release from isolated pancreatic islets in mice
Authors: FLORHOLMEN J. , VONEN B. , GIÆVER A. K. , BURHOL P. G.
Published: December 2008

A simple and rapid method for isolation of pancreatic islets from mice using Percoll as a separation medium is described. Increasing concentrations of secretin from 10‐‐11 to 10‐‐6 m were without effect on the insulin release from the islets at 5.5 mM glucose, whereas significant increases were found at 12 mM glucose. Secretin did not elicit additional increases of the insulin release at 5.5 and 12 mM glucose with 5 mM theophylline. The mechanism by which secretin acts on the pancreatic islets is discussed. Based upon the above observations it is suggested that secretin apparently represents a modulator of the insulin release from the pancreatic islets.
Comparative effects of some calcium‐channel blockers on human peripheral arteries and veins
Authors: SJÖBERG T. , ANDERSSON K.‐E. , NORGREN L. , STEEN S.
Published: December 2008

Comparative effects of some calcium‐channel blockers on human peripheral arteries and veins. Acta Physiol Scand 130, 419–427. Received 5 December 1986, accepted 9 February 1987. ISSN 0001–6772. Departments of Surgery and Clinical Pharmacology, Lund University, Sweden.

We investigated the effects of five different calcium‐channel blockers (CCBs), verapamil, nifedipine, diltiazem, flunarizine and lidoflazine, on contractions evoked an vitro by noradrenaline (NA) in small human arteries and veins from the epigastric region. Vessels were obtained from patients without obvious vascular diseases undergoing surgery because of inguinal hernias. The human superficial epigastric artery has previously been shown to contain mainly α1‐adrenoceptors, whereas in the vein α2‐adrenoceptors predominate. In experiments where NA (10‐5 m) was added non‐cumulatively, it was found that nifedipine was the most potent relaxant agent in both arteries and veins, but that this drug showed no preference for any type of vessel. In contrast verapamil (10‐6 m) and (10‐5 m) diltiazem, flunarizine and lidoflazine inhibited the NA‐induced contractions to a significantly greater extent in the arteries than in the veins. Comparison between diltiazem and nifedipine on contractions induced by cumulative addition to NA showed that both drugs had significantly more depressive effects on arteries than on veins if the vessels were contracted by relatively high concentrations of NA (10‐‐6 and 10‐‐5 m). The results thus confirm the clinical finding that CCBs have more pronounced effects on the arterial than on the venous side of the circulation. They do not support the view that CCBs are more effective inhibitors of α2‐‐ than α1‐adrenoceptor mediated contraction in isolated human blood vessels.
Localization of K‐NPPase and Li+ secretion in the exocrine pancreas of the pig
Authors: BUANES T. , GROTMOL T. , LANDSVERK T. , RÆDER M. G.
Published: December 2008

Localization of K‐NPPase and Li+ secretion in the exocrine pancreas of the pig. Acta Physiol Scand 130, 457–466. Received 30 October 1986, accepted 9 February 1987, ISSN 0001–6772. University of Oslo, Institute for Experimental Medical Research and Surgical Department, Ullevaal Hospital and Department of Pathology, The Norwegian College of Veterinary Medicine, Oslo, Norway.

To study the mode of transepithelial Na+ transport into pancreatic ducts during secretindependent NaHCO3 secretion, Na, K‐ATPase was first localized within the exocrine pancreas of the pig using a cytochemical reaction for K‐dependent p‐nitrophenylphosphatase (K‐NPPase). K‐NPPase staining was confined to the lateral cell membrane bordering the intercellular spaces between ductal cells, negating the possibility of primary active, transcellular Na+ transport into pancreatic ducts. To assess how transepithelial Na+ transport may be coupled to HCO‐3 secretion, net flux of Li+ into pancreatic juice was measured following intravenous systemic Li+ loading of 12 secretin infused, anaesthetized pigs. At plasma Li+ 32 (23–35) mmol I‐1, Li+ displaced Na+ as accompanying cation to secreted HCO3‐‐, and Li+/Na+ in pancreatic juice matched Li+/Na+ in arterial plasma. During superimposed inhibition of pancreatic water flux by hyperglycaemia, Li+ and Na+ were both transported against a transepithelial concentration gradient. Li+ reduced pancreatic HCO3‐ secretion rate by 14 (‐2 to‐20)%, as well as Na, K‐ATPase activity in a separate in vim assay. The finding that Li+ substituted for Na+ in the secretion even during reduced osmotic water flow suggests that Na+ and Li+ are transported together with secreted HCO3‐ into pancreatic juice by an electrogenic mechanism in addition to solvent drag and diffusion.
Influence of oxygen tension and substrates on basal and luteinizing hormone stimulated progesterone production and energy metabolism by isolated corpora lutea of adult pseudopregnant rats
Authors: GÅFVELS M. , SELSTAM G. , DAMBER J.‐E.
Published: December 2008

Influence of oxygen tension and substrates on basal and luteinizing hormone stimulated progesterone production and energy metabolism by isolated corpora lutea of adult pseudopregnant rats. Acta Physiol Scand 130, 475–482. Received 8 January 1987, accepted 23 February 1987. ISSN 0001–6772. Departments of Physiology and Urology & Andrology, University of Umeå, Sweden.

The effect of substrate reduction on in vitro progesterone production by isolated corpora lutea of pseudopregnant rats was studied. Pseudopregnancy was induced by mating adult females with vasectomized males. The rats were killed at different luteal ages and the corpora lutea of pseudopregnancy were identified, dissected free and incubated for 3 h. Six‐day‐old corpora lutea were incubated in the presence of different oxygen tensions as well as different glucose and amino acid concentrations and basal as well as luteinizing hormone (LH)‐stimulated progesterone production was studied. When the oxygen tension was reduced, both basal and LH‐stimulated progesterone production was decreased. At 6 and o kPa, the stimulatory effect of LH on progesterone production was abolished. Lowering the oxygen tension decreased the levels of adenosine‐5′‐triphosphate (ATP) in the tissue and increased lactic acid accumulation in the medium. Omitting both glucose and amino acids while maintaining oxygen tension at 100 kPa abolished the stimulatory effect of LH on progesterone production and decreased the levels of ATP. The present study shows that the corpus luteum in vitro is dependent on a high oxygen tension for maintenance of its progesterone production and LH responsiveness. It is suggested that the amount of ATP available is critical to the degree of LH response. Hypoxia increased luteal glycolysis, but this could only marginally compensate for a low oxygen tension.
Repeated isokinetic plantar flexions at different angular velocities
Authors: GERDLE B. , LÅNGSTRÖM M.
Published: December 2008

Repeated isokinetic plantar flexions at different angular velocities. Acta Physiol Scand 130,495–500. Received 29 October 1986, accepted 23 February 1987. ISSN 0001–6772. Work Physiology Division, National Board of Occupational Safety and Health, and Department of Physical Medicine and Rehabilitation, University of Umeå, Sweden.

Peak torque (PT), contraction work (CW) and mean power (CP) were measured for each of zoo repetitive isokinetic (maximum effort) plantar flexions. Simultaneous recording of integrated electromyograms (iEMG) were obtained from the three parts of the triceps surae muscle. Four tests at different angular velocities (30, 60, 120 and 180 degrees s‐1 (°.s‐1)) were performed with at least 2 weeks between each test. The subjects were eight clinically healthy females (24–36 years). At all four angular velocities CW, CP and PT decreased steeply during the first approximately 70 contractions, followed by a steady‐state level with no further significant decreases. The relative decreases of PT and CP were significantly smaller than for CW at all velocities. The relative CW decline increased with angular velocity; the relative PT and CP decreases were not velocity dependent. Also iEMG activity decreased in two phases during the zoo contractions and were on a significantly lower relative level at 180°.s‐1. However the reduction of range of motion was significantly greater at 180°.s‐1 and when the iEMG activity was compensated for this decrease the relative decreases in electromyographic activity were similar at the four angular velocities. The results indicated that CW was more sensitive to fatigue than PT and CP and that CW fatigue was dependent on angular velocity.
Comparison of VIP and β2‐‐adrenoceptor‐induced relaxations in the circular and longitudinal smooth muscle layers of the rat portal vein
Authors: RYDNINGEN H. T. , OMLAND T. , OPSTAD P. K. , HELLE K. B.
Published: December 2008

Comparison of VIP and β2‐‐adrenoceptor‐induced relaxations in the circular and longitudinal smooth muscle layers of the rat portal vein. Acta Physiol Scand 130, 601–607. Received I I November 1986, accepted 26 February 1987. ISSN 00014772. Department of Physiology, University of Bergen, Norwegian Defence Research Establishment, Kjeller, Norway.

The relative importance of VIP in reduction of vascular tone was studied in circular and longitudinal preparations of the VIP‐innervated rat portal vein. Exogenous VIP inhibited the methoxamine‐evoked contractures in the atropine‐blocked preparations with a lower potency in the inner, circular (pD2= 6.4±0.5, n= 6) than in the outer, longitudinal layer (pD2= 7.7 ± 0.1, n = 6). VIP was also a less efficient relaxant (intrinsic activity (a) = 0.60 ±0.16, n = 6) of the inner than of the outer layer (a= I. 00). The selective (salbutamol) and the non‐selective (isoproterenol) β2‐‐agonists completely relaxed the methoxamine contractures in both layers and the potency (isoproterenol) was higher in the inner (pD2= 6.39 ± 0.32, n = 6) than in the outer layer (pD2= 5.67 ±0.34, n= 6). Plasma from the portal‐mesenteric vein of anaesthetized, fasting rats contained 0.036 nM VIP (median, n= 17). that is, several orders of magnitude lower than the range of VIP concentrations relaxing the methoxamine contracted vein preparations via VIP receptors of the apamin‐blockable category. The results support the hypothesis that a1‐‐adrenoceptor‐induced contractions in the circular layer are predominately relaxed via β2‐‐adrenoceptors while relaxation of the outer layer may occur via VIP receptors, probably activated by local release of the neuropeptide.
Blood pressure regulation, peripheral renin activity and aldosterone in patients with pyelonephritic renal scarring
Authors: JACOBSON S. H.
Published: December 2008

Patients with renal scarring due to previous upper urinary tract infections (UTI) are at risk of developing hypertension and renal insufficiency. In this study glomerular filtration rate (GFR), systolic (SBP) and diastolic (DBP) blood pressure, peripheral renin activity (PRA), plasma (p‐Aldo) and urine aldosterone (u‐Aldo), the urinary excretion of sodium (UNa) and potassium (UK) and the fractional sodium (CNa/CIn) and potassium (CK/CIn) excretion were determined in 22 female patients with verified renal scarring and a history of febrile UTI and in nine age‐matched healthy women with normal i.v. urograms. The patients had significantly lower GFR, higher SBP, higher PRA and higher CK/CIn than the healthy controls. A significant correlation between CNa/CIn and SBP (r= 0.51, P > 0.05), DBP (r= 0.50, P > 0.05) and PRA (r=–0.47, P > 0.05) was found. The ratio of UK/UNa was significantly correlated to SBP (r=–0.43, P > 0.05), DBP (r=–0.44, P > 0.05), PRA (r= 0.65, P > 0.01) and p‐Aldo (r= 0.68, P > 0.01). It is concluded that the renin‐aldosterone system probably is involved in the pathogenesis of hypertension in patients with pyelonephritic renal scarring and that screening determinations of UNa and UK may prove useful for detection of individuals with increased PRA and p‐Aldo.