bluuebunny/crossref_metadata_2025 huggingface dataset:
Protein‐binding of secretin in human plasma
Authors: BURHOL P. G. , JENSSEN T. G. , FLORHOLMEN J. , JORDE R.
Published: December 2008

Protein‐binding of endogenous plasma secretin and of 125I‐labelled secretin incubated with charcoal‐treated plasma examined by gel nitration on a Sephacryl S‐200 Superfine column (16 times 980 mm) showed that secretin in plasma appears both to be bound to at least two different plasma proteins where albumin appears to be the major binding protein, and also to occur as a free molecular form. In addition, protein‐binding studied by incubating 125I‐labelled secretin with charcoal‐treated plasma under various conditions followed by charcoal separation of bound from free label indicated the presence of more specific secretin‐binding sites on the plasma proteins with an avidity comparable to that otherwise reported for albumin as a binding protein. The protein‐binding of 125I‐labelled secretin was optimal or reached equilibrium after 2 days incubation at 20oC and first after 8 days incubation at 4oC. Also, the protein‐binding of 125I‐labelled secretin was higher at an incubation temperature of 20 than of 4oC; was optimal at pH 7.4; increased with increasing amounts of charcoal‐treated plasma up to an amount of 800 μl in our assay system before levelling off; and increased in a constant and predictable manner with increasing amounts of 125I‐labelled secretin at least with the amounts of labelled secretin examined here.
A method for in vitro studies on acid formation in human parietal cells. Stimulation by histamine, pentagastrin and carbachol
Authors: MÅRDH S. , NORBERG L. , LJUNGSTRÖM M. , WOLLERT S. , NYRÉN O. , GUSTAVSSON S.
Published: December 2008

Cells were isolated from human gastric mucosa on a large scale from gastric resection specimens and on a microscale from endoscopic biopsies by sequential incubations with pronase and collagenase. The accumulation of aminopyrine (AP) was used as an index of acid production in the parietal cells. Basal accumulation was about 0.2 pmol AP/104 parietal cells. Addition of histamine, db‐cAMP, pentagastrin and carbachol increased the aminopyrine accumulation. Maximal accumulation was of the order of 1000–2800% of the control and was obtained after stimulation by 10‐4 M histamine and by 10‐3 M db‐cAMP. Stimulation by pentagastrin and by carbachol reached 200 to 350% of the control. EC50 was 2 times 10‐6 M for histamine, 10‐8 M for pentagastrin, and 4 times 10‐6 M for carbachol. Human parietal cells were enriched from a mixture of gastric mucosal cells by isopycnic centrifugation on density gradients of Percoll. A parietal cell fraction with a purity of 83% was obtained. The density of human parietal cells was estimated to 1.06 g ml‐1.
Graded effects of oxygen and respiratory inhibitors on cell metabolism and spontaneous contractions in smooth muscle of the rat portal vein
Authors: LÖVGREN BJÖRN , HELLSTRAND PER
Published: December 2008

The basis for the hypoxic relaxation of spontaneous activity in the rat portal vein was investigated by comparing responses to oxygen and the respiratory chain inhibitors amobarbital and cyanide. With the inhibitors, 02 consumption (JO2) is uniformly decreased throughout the cell mass, and thus O2 gradients in the tissue are avoided. Hence the effects are not to be attributed to all‐or‐none inhibition in anoxic regions, a possibility that might complicate the interpretation of responses to hypoxia. With stepwise reduction in PQ2 (96 to o % O2 in N2 + 4 % CO2) or increasing concentration of inhibitor (0–5 mmol), JO2, decreased with a concomitant reduction in mean contractile activity (p̄) and increase in lactate production (J LA). The calculated ATP production (J ATP) was linearly related to p̄ for p̄ > 10% of the control value in 96% O2, with the same slope for hypoxia and both inhibitors. In this range the reduced JATP with can largely be attributed to decreased metabolic demand of contraction, as evident from a comparison with the responses to hypoxia of portal veins relaxed in nominally Ca2+‐free medium. With reduced PO2 or increased amobarbital concentration the tissue content of phosphocreatine decreased, whereas ATP remained constant for p̄ gt; 10% of control. Similar responses to hypoxia and respiratory inhibition demonstrate graded effects on metabolism and contractility in the vascular smooth muscle cells, correlating with reported vasodilatory effects of these interventions in vivo.
A spectrophotometric method for measuring oxygen consumption in monolayers of cultured endothelial cells
Authors: HULTBORN R. , KJELLSTRÖM B. THOMAS , RISBERG BO
Published: December 2008

A new method for measuring oxygen consumption in monolayer cell cultures is described. Cells are cultured in shallow microchambers etched in glass chips. A haemoglobin solution is added and the microchambers are sealed airtight, the oxygenated haemoglobin solution serving as an indicator of oxygen tension within the microchamber as well as a source of oxygen. With cellular extraction of oxygen, an increasing amount of reduced haemoglobin is formed within the microchamber resulting in an increased absorbance of the haemoglobin solution at 435 nm. With a specially prepared device, it is possible to record this absorbance change with an ordinary laboratory spectrophotometer and, from this recording, it is possible to calculate the respiratory rate, provided the number of cells (or any other quantity of biological material), microchamber volume and haemoglobin concentration are known. Repeated measurements on the same undisturbed culture is possible. The system was tested on monolayer cultures of endothelial cells from the rat pulmonary artery.
Concentrations and contractile effects of substance P in the human ampullary‐isthmic junction
Authors: FORMAN A. , ANDERSSON K.‐E. , MAIGAARD S. , ULMSTEN U.
Published: December 2008

From 20 women undergoing hysterectomy, strip preparations were isolated from the outer, longitudinal and the inner, circular smooth muscle layer of the ampullary‐isthmic junction (AIJ), together with small arterial segments dissected as ring preparations from the root of the mesosalpinx. The specimens were mounted in organ baths and isometric tension was recorded. In addition, tissue concentrations of substance P (SP) in the ampulla, AIJ and utero‐tubal junction were determined by radioimmunoassay. Tissue concentrations of SP expressed as pmol.g tissue‐1(wet weight, ± SE) amounted to 3.09 ± 1.40 in the utero‐tubal junction, 1.08 ± 0.299 in the AIJ and 0.742 ± 0.299 in the ampulla. In strips of circular muscle, SP at concentrations of 10‐7‐3 times 10‐6mol.l‐1elicited a combined phasic and tonic response and in longitudinal muscle a mainly tonic contraction was produced. In both tissues, contractions elicited by SP were rapidly abolished in calcium‐free medium. Nifedipine abolished the phasic contraction elicited in circular muscle by SP while the tonic response was resistant. The contraction in longitudinal muscle was reduced by 20–30%. Vasoactive intestinal polypeptide (VIP) decreased tension in preparations contracted by SP, prostaglandin F2αand K+‐depolarization (124 mmol.l‐1). In unstimulated oviductal arterial preparations, SP had no effect, while the peptide induced a transient relaxation of noradrenaline contracted preparations, and slightly decreased tension of K+‐depolarized vessels. The results suggest that SP may be involved in the control of motility of the human AIJ.
Fatigue in frog skeletal muscle fibres and effects of methylxanthine derivatives
Authors: KHAN A. RAUF , BENGTSSON BENGT
Published: December 2008

The influence of theophylline and the related drug caffeine on the mechanical performance of fatigued muscle fibre isolated from semitendinosus muscle ofRana temporaria(2.5–6.7 °C) was investigated. The fibre was stimulated supramaximally to produce 1 s fused tetani and 2 s and 10 s partially fused tetani at intervals of 10 min. Fatigue was produced by shortening the contraction interval to 15 and 30 s. This caused a 15–20% decline in the maximum tension during fused tetanus and a 40–50% decline during partially fused tetanus. Theophylline and caffeine (0.1‐0.5 mM) did not change the maximum tension developed by the fatigued fibre during fused tetanization. Both drugs, however, markedly increased the tension output of the fatigued muscle fibre during partially fused tetanus. It was observed that the increase in partially fused tetanic tension by theophylline and caffeine was associated with an increase in the degree of fusion. This later effect was even more pronounced in the presence of diethyl‐stilboestrol. It is concluded that these drugs may not reverse the metabolic changes caused by fatigue, since they are unnable to increase fused tetanic force of a fatigued muscle fibre. The increase in partially fused tetanic tension of a fatigued muscle fibre by these drugs is probably due to enhancement of the activator calcium release from the sarcoplasmic reticulum in response to stimulation.
Ba2+‐induced changes in the Na+‐ and K+‐permeability of the isolated frog skin
Authors: NIELSEN ROBERT
Published: December 2008

Addition of the K+‐channel blocking agent Ba2+ to the basolateral solution (in a concentration which is assumed to block the K+‐flux via the K+‐channels completely) resulted initially in a two‐thirds reduction in the short‐circuit current (SCC), followed by a complete recovery of the SCC. To examine the reason for this recovery, experiments were carried out which made it possible to calculate the Na+‐permeability of the apical membrane (PaNa) and the K+‐permeability of the basolateral membrane (PbK). The presence of Ba2+ had no significant effect on the cell volume and the cellular Na+‐ and K+‐concentration. Addition of Ba2+ resulted in a depolarization of the intracellular potential (Vscc) from a control value of ‐ 76.3 ± 2.8 mV to ‐ 15.1 ± 1.7 mV. Although a complete recovery in the SCC was observed, Vscc did not recover. The K+‐flux across the basolateral membrane was estimated from washout experiments. The washout of 42K+ (the K+‐efflux) could be described by a single exponential component with a half time of 30–70 min. The addition of Ba2+ during the washout resulted in a transient decrease in 42K+‐efflux from the epithelium. From Vscc and the cellular K+ and Na+‐concentration and the coupling ratio of the Na‐K pump, it was found that Na+‐permeability of the apical membrane was 6.5.10‐7 cm.s‐1 before the addition of Ba2+ and 1.7.10‐6 cm.s‐1 when the SCC had recovered after the addition of Ba2+ and PbK changed from 8.8.10‐6 cm.s‐1 to 1.5.10‐6 cm.s‐1. Thus, the observed recovery in SCC was due to a considerable increase in Na+‐permeability of the apical membrane and the presence or appearance of a small Ba2+‐insensitive K+‐permeability in the basolateral membrane.
Ascorbic acid uptake to isolated nerve terminals and secretory granules from ox neurohypophyses
Authors: THORN N. A. , CHRISTENSEN B. L. , JEPPESEN C. , NIELSEN F. S.
Published: December 2008

Isolated nerve terminals (neurosecretosomes) from cow neurohypophyses accumulated radioactivity when they were incubated with L[14C]‐ascorbic acid in an ionic medium dominated by NaCl. Uptake of radioactivity was saturable with ascorbic acid concentration. Replacement of Na+with Li+in the incubation medium or presence of ouabain inhibited the accumulation. Isolated, purified cow neurosecretory granules contained 14 ± 2 nmol ascorbate (n= 10) per mg of protein. When such granules were incubated with L[14C]‐ascorbic acid in a KCl dominated medium, they took up radioactivity slowly. The accumulation was not saturable with ascorbic acid concentration and was not influenced by the presence of Mg2+ATP.
Potassium permeability in rat myelinated nerve fibres
Authors: BRISMAR T. , SCHWARZ J. R.
Published: December 2008

Potential clamp experiments were performed at 21–23°C on single myelinated rat nerve fibres isolated from the sciatic nerve. A small delayed K‐permeability (PK) was regularly identified in the normal rat node amounting to 0.067 cm3 s‐1× 10‐9 at large positive potentials. Measurements in isotonic KCl showed that about two‐thirds of PK was already activated at resting potential. Substitution of Cs for axoplasmic K demonstrated that the rat node had large leak currents (33 nS). The leak current provided the main part of the repolarizing outward current. 10 mM tetraethylammonium chloride (TEA) slowly (= 2 min) and incompletely (50%) blocked both PK activated at resting potential and the delayed increase in PK. 1 mM 4‐aminopyridine (4‐AP) had less effect on PK.
β‐adrenoceptor agonists do not cause tremor in the conscious rat
Authors: HALLBERG HELÉNE , ALMGREN OLLE
Published: December 2008

The ability of some β‐adrenoceptor agonists to induce tremor via skeletal muscle β2‐adrenoceptors in conscious unrestrained rats has been investigated. Tremor was assessed by visual observation and by an objective method based on accelerometry. Infusion of isoprenaline or terbutaline did not cause tremor, neither did β‐stimulation potentiate an established mild tremor produced by central muscarinic receptor stimulation. Since β‐agonists readily produce tremor in man via skeletal muscle β2‐adrenoceptor stimulation, our findings indicate that these receptors have a different function in the rat.
Changes in growth hormone binding and metabolic effects of growth hormone in rat adipocytes following hypophysectomy
Authors: GAUSE INGRID , EDÉN STAFFAN , ISAKSSON OLLE , DIGIROLAMO MARIO , SMITH ULF
Published: December 2008

Growth hormone (GH) binding and the effect of GH and insulin on glucose metabolism in rat adipocytes were studied at various time periods following hypophysectomy. Male rats were hypophysectomized at 33–34 days of age. After 6 h, 20 h or 3, 7 and 14 days adipocytes were prepared from epididymal fat pads by mild collagenase digestion (0.5 mg. ml‐1, 60 min, 37°C). Glucose metabolism was studied by determining the production of CO2 from [14C]glucose and the incorporation of [14C]glucose into lipids. GH binding was measured in cell aliquots using [125I]hGH. No difference in GH binding to adipocytes was observed between control rats and rats hypophysectomized or sham‐operated 6 h earlier. GH binding was significantly decreased 20 h after hypophysectomy and declined further with time after hypophysectomy. Adipose tissue from normal rats is usually refractory to the insulin‐like effect of GH. Adipocytes isolated from normal rats were, however, usually responsive to GH immediately after cell isolation, suggesting that refractoriness to the insulin‐like effect of GH was lost during the time required for the preparation of adipocytes. The magnitude of the response to GH in adipocytes progressively declined with time after hypophysectomy. The decreased responsiveness to GH with time after hypophysectomy parallelled the decrease in GH binding. The results suggest that the pituitary, directly or indirectly, is necessary for the maintenance of GH binding sites in adipose tissue and that these binding sites are related to the insulin‐like effect of GH.
Comparison between the steroidogenic responses after pulsatile and continuous administration of gonadotrophin releasing hormone to superfused rat follicles
Authors: HEDIN LARS
Published: December 2008

Gonadotrophin releasing hormone (GnRH) exhibits both stimulatory and inhibitory effects on the ovarian tissue in the rat. For the action of GnRH on the pituitary, the mode of administration is of utmost importance. The binding characteristics and regulation of the GnRH receptors found in the ovary are very similar to those of the pituitary. The aim of the present study was to compare the steroidogenic response of superfused, preovulatory rat follicles to continuous and pulsatile administration of a GnRH analogue (GnRHa). The results obtained with a single pulse of luteinizing hormone (LH) served as a control. Repeated pulses (1 pulse. h‐1) or continuous administration of GnRHa was found to be more effective than a single pulse of GnRHa. The effect of GnRHA, irrespective of the mode of administration, was most pronounced on the secretion of 20α‐OH‐progesterone (20α‐OHP). Also the release of testosterone (T) and oestradiol (E2) was stimulated but to a lesser extent. In comparison to LH, the GnRHa response was delayed and without detectable release of cyclic AMP (cAMP). These results illustrate that pulses of GnRH stimulate the steroidogenesis in preovulatory follicles. In contrast to the effects of GnRHa on the pituitary, the modes of administration seem to be of less importance for the stimulation of the rat ovary.
Carbonic anhydrase in epithelia and fenestrated juxtaepithelial capillaries of Macaca fascicularis
Authors: LÜTJEN‐DRECOLL ELKE , EICHHORN MICHAEL , BARANY ERNST H.
Published: December 2008

Thirty‐nine epithelia of the monkey Macaca fascicularis and their underlying connective tissue were stained for carbonic anhydrase (CA) and studied by light microscopy. The capillaries immediately adjacent to the epithelium, ‘juxtaepithelial’, were also studied by electron microscopy with special attention to presence or absence of fenestrations. Only juxtaepithelial capillaries stained. These were fenestrated under many epithelia and all fenestrated juxtaepithelial capillaries stained. Often staining and fenestration were limited to the part of their circumference facing the epithelium. There was a strong association P < 0.002 between CA‐staining and fenestration of the capillaries, a moderately strong association P < 0.02 between CA‐staining of the membrane of the epithelium and the adjacent capillaries, and no association between staining of the epithelial cytoplasm on the one hand and the epithelial membrane or the capillaries on the other. Fenestrated capillaries containing CA despite unstained epithelia were found in the thyroid, parathyroid, adrenal cortex, islets and anterior pituitary, and also, but not consistently, in the prostatic and the seminal glands. Unfenestrated capillaries containing CA were found in the stomach, colon and lung, and in the Graffian follicle and Fallopian tube. The hypothesis is advanced that capillary CA besides conventional functions plays a part in conserving the state of fenestration of the endothelium and that CA‐inhibitors could exert part of their therapeutic and side actions by reducing fenestrations.
X‐ray microanalysis of resting and stimulated rat pancreas
Authors: ROOMANS GODFRIED M. , WEI XU
Published: December 2008

The elemental distribution in acinar cells of rat pancreas was investigated by X‐ray microanalysis of thin, freeze‐dried cryosections. In the resting cell, the highest calcium concentrations were found in the basal part of the cell (including the endoplasmic reticulum) and in the zymogen granules. Mitochondrial calcium concentrations were low. Zymogen granules were rich in sulphur, but low in phosphorus, sodium and potassium. Stimulation of the pancreas by perfusion in vivo with the cholinergic agonist carbachol caused a significant decrease of the calcium concentration in the basal part of the cell and an increase in the calcium concentration in the apical part of the cell. The mitochondrial calcium concentration was not significantly altered. In addition, increased sodium and decreased potassium concentrations, giving rise to a significant increase in Na/K ratio were observed in all cell compartments measured, except in the zymogen granules.
Plasma levels of oxytocin increase in response to suckling and feeding in dogs and sows
Authors: UVNÄS‐MOBERG K. , STOCK S. , ERIKSSON M. , LINDÉN A. , EINARSSON S. , KUNAVONGKRIT A.
Published: December 2008

The objective of the present study was to investigate whether oxytocin is released in response to feeding in analogy to the response induced by suckling. Therefore, repeated plasma samples were drawn from dogs and pigs during feeding and suckling and oxytocin levels were determined by radioimmunoassay. As expected suckling gave rise to immediate and short‐lasting increases of oxytocin levels in both species. More surprisingly, feeding in female and male dogs as well as in lactating sows was accompanied by a similar‐sized rise of oxytocin levels. The oxytocin peak sometimes occurred before the actual period of suckling or feeding, suggesting that the output of oxytocin had been conditioned to visual, olfactory or auditory stimuli associated with both types of situations. It is well known that oxytocin is released in lactating animals in response to touching of the teats. It is possible that also the presence of food in the gastro‐intestinal tract activates neurogenic mechanisms which stimulates the release of oxytocin. Since oxytocin causes a release of insulin and VIP (vasoactive intestinal polypeptide), peptides which appear in the circulation following both suckling and feeding, it is suggested that oxytocin may be involved in the control of the suckling‐ and feeding‐related output of these peptides.
Diurnal rhythm of melatonin in human saliva
Authors: VAKKURI O.
Published: December 2008

Human mixed saliva extracted with chloroform was found to contain immunoreactive melatonin which eluted in HPLC as synthetic melatonin. There was a clear diurnal rhythm in saliva melatonin with low day and high night levels. A similar rhythm was observed in serum. The high night levels in saliva were lower than the corresponding levels in serum. The calculated secretion rate of melatonin into saliva was <0.5‐0.9 pmol·h‐1during the day and 1.0–2.4 pmol·‐1during the night. Saliva sampling can be used as a simple and non‐invasive way of studying melatonin secretion in human body.
Some effects of substance P on central respiratory control in rabbit pups
Authors: YAMAMOTO YUJI , LAGERCRANTZ HUGO
Published: December 2008

Respiratory effects of substance P (SP) have been studied in rabbit pups (1–30 days). Rabbits were either anaesthetized with urethane or decerebrated at mid‐collicular level. Respiratory activity was measured with a pneumotachograph or in some cases as efferent phrenic nerve activity. SP applied to the exposed medulla oblongata from the dorsal side caused an increase of both tidal volume and respiratory frequency. The respiratory stimulation was more pronounced in decerebrate animals than in anesthetized ones. Moreover, this effect was most prominent in the youngest animals. A SP analogue (d‐arg1‐d‐Pro2,d‐Trp7, 9, Leu11)‐SP was found to block the ventilatory effects of SP and to decrease the hypoxic response, while the hypercapnic response was preserved. The results suggest that SP is involved in the control of respiration, possibly mediating the hypoxic response, and that this role is more important in the neonatal period.
Influence of acetylcholine, peptides, and other vasodilators on endogenous noradrenaline overflow and vasoconstriction in canine blood perfused gracilis muscle
Authors: KAHAN THOMAS , DAHLÖF CARL , HJEMDAHL PAUL
Published: December 2008

The effects of acetylcholine, substance P and vasoactive intestinal polypeptide (VIP) on the endogenous noradrenaline (NA) overflow were compared to those of two other vasodilators, nitroglycerin and felodipine, neither of which are thought to influence NA neurotransmission in blood perfused skeletal muscle. The lack of prejunctional effects of nitroglycerin was verifiedin vitro.The sympathetic nerve stimulation (SNS) evoked NA overflow was reduced by 37 ± 9% by a dose of acetylcholine which reduced the perfusion pressure at rest by 44 ± 6%. Conversely, atropine tended to enhance SNS evoked NA overflow. Acetylcholine reduced the vasoconstrictor responses to SNS when compared to the responses observed with an equipotent vasodilatory dose of, e.g. nitroglycerin. The SNS evoked NA overflow was not influenced by a moderate mechanical blood flow reduction or by pronounced reductions of vascular resistance induced by either substance P, VIP, nitroglycerin or felodipine, supporting the idea that the transport of NA from nerve terminal to blood is not importantly influenced by moderate decreases in blood flow or vascular tone. Prejunctional muscarinic inhibition of NA release in skeletal muscle was verified underin vivoconditions, but the other substances tested did not influence sympathetic neurotransmission. Endogenous NA overflow appears to mirror NA releasein vivoalso when diffusion is influenced by changes in blood flow or vascular tone in this experimental model.
Effects of ageing on cardiac performance and coronary flow in spontaneously hypertensive and normotensive rats
Authors: FRIBERG P. , NORDLANDER M. , LUNDIN S. , FOLKOW B.
Published: December 2008

The aim of the present study was to assess the influence of ageing on cardiac function and coronary flow in Wistar Kyoto normotensive rats (WKY, 16 and 78 weeks of age) and spontaneously hypertensive rats (SHR) of the same age. Cardiac function was determined on isolated hearts by means of an antegrade heart perfusion technique. Left atrial pressure and peak aortic pressure could be altered independently of each other. Recordings of cardiac output and coronary flow were then obtained at both normotensive and hypertensive levels of peak aortic pressures. Peak stroke volume (SV) was reduced with age in both WKY and SHR. Peak SV determined at normotensive pressure loads became diminished with age in WKY, while it at hypertensive pressure loads showed a small decline with age, since peak SV was low as early as 16 weeks of age. The age‐dependent fall in cardiac performance was greater in SHR than in WKY, due to the enhanced peak SV in 16‐week‐old SHR at hypertensive pressure loads. Peak SV was markedly decreased at normotensive pressure levels in both 16‐ and 78‐week‐old SHR v age‐matched WKY. Coronary flow per unit tissue declined with age both in WKY and SHR. Coronary flow was also lower in SHR compared to age‐matched WKY. With ageing this elevated performance was reduced down to the same level as in 78‐week‐old WKY. The age‐related coronary flow reduction and the consistently reduced flow in SHR indicate a structural narrowing of the coronary vascular bed, particularly in SHR.
Cation exchanger properties of isolated rat peritoneal mast cell granules
Authors: UVNÄS BÖRJE , ÅBORG CARL‐HUGO , LYSSARIDES LEENA , THYBERG JOHAN
Published: December 2008

The synthetic carboxylic cation exchanger resin Amberlite IRC‐50 was charged with histamine by suspension in histamine‐containing solution with admixture of [14C]histamine. Mast cell granules were isolated from mast cells suspended in isotonic sucrose. The release of histamine induced from the two materials by superfusion with isotonic NaCl and KC1 solutions showed identical kinetics, in accordance with the view that the release of histamine is due to a cation exchange: Na+(K+)→ Hi+at carboxyl groups in the granule heparin‐protein complex.
Characterization of the contractile effect of neuropeptide Y in feline cerebral arteries
Authors: EDVINSSON LARS
Published: December 2008

The action of neuropeptide Y (NPY), which coexists with noradrenaline (NA) in perivascular sympathetic nerves, has been examined on feline cerebrovascular smooth muscle using a sensitive in vitro. system. The direct cerebrovascular responses of peptides with structural similarities with NPY, peptide YY (PYY), avian (APP), and bovine (BPP) and human (HPP) pancreatic polypeptides, have been compared with that of NPY on isolated feline cerebral arteries. The relative potency for contractions induced by the peptides is: NPY, PYY > APP > BPP, HPP. The alpha‐adrenoceptor antagonist rauwolscine, which blocked the response to noradrenaline (NA), had no effect on NPY‐induced contractions. Neuropeptide Y significantly potentiated contractions induced by 10‐6M NA, but not by 10‐5M. Withdrawal of Ca2+from the extracellular medium for 30 min reduced the contractile response to NPY in cerebral vessels by about 80%. Subsequent readdition of Ca2+caused reproducible contractions which were inhibited by the calcium entry blocker nimodipine. Nimodipine also relaxed isolated middle cerebral artery segments contracted by NPY and NA in a concentration‐dependent manner. The data suggest that NPY mediates contraction of cerebrovascular smooth muscle via a mechanism that is dependent on the concentration of extracellular calcium.
Effects of ganglioside GM1 treatment on striatal glucose metabolism, blood flow, and protein phosphorylation of the rat
Authors: AGNATI L. F. , FUXE K. , BENFENATI F. , ZOLI M. , OWMAN C. , DIEMER N. H. , KÅHRSTROM J. , TOFFANO G. , CIMINO M.
Published: December 2008

Effects of ganglioside GM1 administration have been studied in unilaterally partially hemitransected rats on striatal energy metabolism, using the radioactive deoxyglucose (DG) technique, on striatal blood flow, using radiolabelled iodoantipyrine (IAP) as tracer, and on cyclic AMP (cAMP) and Ca2+ induced protein phosphorylation in striatal membranes (P2 fraction). Ganglioside GM1 treatment counteracted the imbalance in striatal energy metabolism, in striatal blood flow, as well as in protein phosphorylation found between the striata of the lesioned and unlesioned side, possibly due to excitatory effects on the lesioned side and inhibitory effects on the unlesioned side. In intact animals, GM1 treatment produced a reduction in cAMP and Ca2+ induced striatal protein phosphorylation. Facilitatory actions of the ganglioside GM1 dominate following a lesion, probably due to its possible function as a modulator of receptors for neuronotrophic factors, leading to restoration of metabolic rate and of cAMP and Ca2+ induced protein phosphorylation in the striatum of the lesioned side. The results emphasize that ganglioside GM1 treatment can restore the metabolism of a partially innervated striatum towards normal, as evaluated both at the level of the entire striatal structure by means of the DG and IAP techniques and at the molecular level by means of studies on the cAMP and Ca2+ induced protein phosphorylation.
Interaction between ventricular cells during the early part of excitation in the ferret heart
Authors: SUENSON M.
Published: December 2008

The source‐load interaction during impulse propagation of excited and unexcited cells respectively was studied in the working myocardium. Velocity of propagation and the shape of the early part of the action potential was measured in ferret papillary muscles or trabeculae with the preparation surrounded by either a large volume or a thin layer of Tyrode solution, the latter situation being established by means of a silicone fluid bath technique. Quick changes between the two situations resulted in changes in the time constant of the foot of the action potential and maximal rate of depolarization of the action potential and in changes in excitation lag of the more deeply placed cells with respect to the surface cells. These results could be explained by the effect of changes in the shape of the wavefront of excitation. With a large Tyrode volume around the preparation, corresponding to physiological conditions, the curved configuration of the wavefront of excitation was so pronounced that one‐dimensional cable theory was highly inadequate to describe the conditions for propagation.
Subcellular storage and axonal transport of neuropeptide Y (NPY) in relation to catecholamines in the cat
Authors: FRIED G. , LUNDBERG J. M. , THEODORSSON‐NORHEIM E.
Published: December 2008

The subcellular storage of neuropeptide Y‐like immunoreactivity (NPY‐LI) in peripheral sympathetic neurons and adrenal gland as well as its axonal transport in the sciatic nerve was studied in relation to catecholamines in the cat. In the subcellular fractions from different parts of sympathetic neurons, i.e. cell bodies (coeliac ganglia), axons (sciatic nerve) and terminals (spleen), the NPY‐LI was found together with noradrenaline (NA) in heavy fractions assumed to contain large dense‐cored vesicles. In addition, minor lighter fractions in the coeliac ganglion contained NPY‐LI. The molar ratio between vesicular NA and NPY was high in the terminal regions (150 to 1) and much lower in axons and cell bodies (10 to 1), thus reflecting the different mechanisms of resupply for classical transmitter and peptide. In the adrenal gland the NPY‐LI was mainly located in the catecholamine‐storing chromaffin‐granule fraction and also to a smaller extent in lighter fractions. Using reversed‐phase HPLC, one molecular form of NPY‐LI corresponding to porcine NPY was found in the coeliac ganglion, while the adrenal medulla also contained minor peaks with NPY‐LI in addition to the main form, which co‐eluted with porcine NPY. NA was stored both in light and heavy fractions in the spleen, while it was mainly found in heavier fractions in the sciatic nerve. In the coeliac ganglion, most of the noradrenaline was present in a non‐particulate form. The anterograde transport rate for NPY‐LI in the sciatic nerve was estimated to be about 9 mm h‐1. A minor retrograde transport of NPY‐LI was also detected. In conclusion, the present data suggest that NPY, a peptide with sympathoactive actions, is co‐stored with NA in heavy fractions corresponding to large dense‐cored vesicles, while light fractions with small dense‐cored vesicles probably contain NA but not NPY‐LI. The main resupply of NPY to terminals is, in contrast to NA, most likely by axonal transport, which implicates differences in the storage, turnover and release of these co‐existing substances in the sympathoadrenal system.
Neuropeptide Y (NPY) and sympathetic control of blood flow in oral mucosa and dental pulp in the cat
Authors: EDWALL BJÖRN , GAZELIUS BERTIL , FAZEKAS ÁRPÁD , THEODORSSON‐NORHEIM ELVAR , LUNDBERG JAN M.
Published: December 2008

Neuropeptide Y (NPY) immunoreactivity (‐IR) was found to be present in perivascular nerves in the cat dental pulp and oral mucosa. Many ganglion cells in the superior cervical ganglion also contained NPY‐IR. Ligation of the inferior alveolar or lingual nerves produced an accumulation of NPY‐IR in axons proximal to the site of ligation, suggesting an anterograde axonal transport of the peptide. After unilateral sympathectomy the NPY‐IR disappeared in the dental pulp and oral mucosa on the ipsilateral side. Reversed phase high performance liquid chromatography showed that the main peak of NPY‐like immunoreactivity found in the superior cervical ganglion co‐chromatographed with synthetic porcine NPY. Changes in blood flow in dental pulp or oral mucosa were measured indirectly by recording local clearance of125I during electrical stimulation of the sympathetic nerve or during close intra‐arterial infusion of noradrenaline or NPY. All three procedures resulted in a pronounced decrease in local blood flow of a similar magnitude in both tissues. After a‐adrenoceptor blockade with phentolamine, the vasoconstrictor effect of noradrenaline was abolished. However, the effect of sympathetic stimulation after phentolamine was only partially reduced (23–54%) and the response to NPY was almost unaffected by the a‐receptor blockade. The remaining effect of sympathetic stimulation after phentolamine was abolished by guanethidine. However, the response to NPY was not changed by the latter drug. In conclusion, the vasoconstrictor response in the dental pulp and oral mucosa caused by activation of sympathetic nerves is more resistant to phentolamine than the response induced by infusion of exogenous noradrenaline. Since NPY is probably co‐localized with noradrenaline in the sympathetic perivascular nerves and NPY reduces local blood flow,it is proposed that this peptide is involved in sympathetic vascular control in oral tissues.
Blood pressure, heart rate and EMG in low level static contractions
Authors: FALLENTIN NILS , SIDENIUS BJØRN , JØRGENSEN KURT
Published: December 2008

The purposes of the present investigation were: (1) to evalute a possible use of changes in the mean spectral frequency (MSF) of the EMG power spectra as a measure of reflex cardiovascular responses originating from the muscles durig static exercise; and (2) to study the relation between muscle fibre composition, EMG, and the cardiovascular response. Heart rate (HR), artirial blood pressure (BP), myoelectric signal (EMG), and intramuscular temperature (Tm) were measured during prolonged static contractions in feive healthy male subjects (25–44 yrs). Two studies were performed. In study 1 constant EMG contraction muscle force in the first 5 s of the knee‐extensor contraction was set to 20% MVC, (maximal voluntary contraction), and in the rest of the 5 min contraction the myoelectric signal was kept constant by visual feedback from an oscilloscope. In study II, (constant force contraction) two 1 h 7% MVC isometric contractions of the elbow‐flexors and extensors were performed on two separate days. During the 5 min constant EMG contranson, the force fell from 20 to 11% MVC, mean BP (MAP) increased from 97±5 to 120±4 mmHg (P < 0.01), and the EMS MSF decreased from 87±16 to 66±9 Hz (P < 0.01). The decrease in MSF was strongly correlated to the increase in MAP (r = 0.96, P < 0.01). The intramuscular temperature showed a small increse from 34.3 °C (P < 0.01). During the 1 h constant force contraction involving m. triceps, MAP increased from 104±10 to 120±12 mmHg, with a simultaneous decrease in the EMG MSF from 96±11 to 70±19 Hz and an increase in the EMG anplitude (247% of the initial value). In the contractions involving m. biceps, however, both MAP and EMG MSF remained almost unchanged, but EMG amplitude increased (197% of the initial value). Very modest changes in HR were observed: 63±6 to 66±6 beats min‐1 and 61±5 to 59±7 beats min‐1 in the contractions involving m. triceps and m. biceps, respectively. The intramuscular temperature increased simultaneously, 1.3 °C and 0.7 °C in m. triceps and m. biceps, respectively. The results from the constant EMG contractions indicate the existence of a common ‘trigger’ for both the increase in BP and the decrease in EMG MSF; and the extracellular [K] is put forward as a candidate. In study II, the demonstrated link between muscle fibre composition and cardiovascular responses during light, static work is explained from differences in metabolic characteristics and in the maintenance of homeostasis in slow and fast twitch muscles, respectively. Finally, the relative importance of central and peripheral control mechanisms in regulation of the circulation during static work is discussed on the basis of the demonstrated changes in EMG MSF and amplitude. It is concluded that peripheral control mechanisms seem to dominate in low level muscle contractions of long duration.
The influence of felodipine and diethyl‐stilboestrol on [3H]noradrenaline release in the rat trachea
Authors: BENGTSSON BENGT , KHAN A. RAUF
Published: December 2008

The fractional release of [3H]noradrenaIine was measured in rings from the rat trachea. Transmitter release was induced either by isotonic KC1 (124 mM) or by 2.5 mM Ca added to a Ca‐free depolarizing solution. Felodipine, a Ca antagonist (10‐4M), had no effect on the basal release of [3H]NA whereas it reduced the overflow of transmitter caused by KC1 or Ca. Diethyl‐stilboestrol (25 μM), which also inhibits Ca influx in smooth muscle, had a stronger inhibitory effect than felodipine on [3H]NA release induced by high K and addition of Ca. Basal efflux of [3H]NA was increased by diethyl‐stilboestrol. This increase also occurred in the absence of extracellular Ca.
Effects of high and low sodium diets on the resistance vessels and their adrenergic vasoconstrictor fibre control in normotensive (WKY) and hypertensive (SHR) rats
Authors: NILSSON HOLGER , ELY DANIEL , FRIBERG PETER , KARLSTRÖM GÖRAN , FOLKOW BJÖRN
Published: December 2008

As part of our studies in normotensive (WKY) and hypertensive (SHR) rats concerning the cardiovascular effects of 240‐fold variations in sodium (Na) intake, the present experiments explore how vascular design, smooth‐muscle sensitivity to noradrenaline and adrenergic vasoconstrictor fibre function are affected. In vitro comparisons were performed on pair‐perfused hindquarter vascular beds and on paired small mesenteric arteries (diameter 150–200 μM), using a two‐vessel Mulvany‐Halpern myograph. Preparations were taken from WKY and SHR which between 5 and 12–13 weeks of age were on ‘low’ (LNa, 0.5), ‘control’ (CNa, 5), ‘high’ (HNa, 50) or ‘very high’ (vHNa, 120 mmol Na 100 g‐1 food) sodium diets. Structural vascular adaptation occurred only when arterial pressure was altered (only in LNa SHR). In both preparations smooth‐muscle sensitivity and dose‐response curves to noradrenaline remained unaffected by the Na diets. However, in both LNa groups the frequency‐response curves to vasoconstrictor fibre stimulation in the small arteries were displaced to the right of the CNa one, with generally attenuated responses, while the curves of particularly the vHNa arteries were displaced to the left, with enhanced responses. Inhibition of NaKATPase by ouabain particularly enhanced the neurogenic responses, but to similar extents in all Na groups. Thus, low sodium intake apparently reduces the transmitter release/impulse in adrenergic neurons, while it increases the transmitter stores. High sodium intake has the opposite effects. These adaptations of adrenergic neuronal function may be one of the most important long‐term consequences of altered sodium intake.
Renal interstitial pressure measured in the subcapsular space using an in vivo oncometer
Authors: BOBERG ULF , MULLER‐SUUR CHARLOTTE , PERSSON A. ERIK G.
Published: December 2008

BOBERG, U., MÜLLER‐SUUR, C. & PERSSON, A.E.G. 1985. Renal interstitial pressure measured in the subcapsular space using an in vivo oncometer. Acta Physiol Scand125, 377–381. Received 8 March 1985, accepted 1 May 1985, ISSN 0001–6772. Department of Physiology and Medical Biophysics, and Department of Urology, Uppsala University, Uppsala, Sweden.

Continuous measurements of renal interstital pressure are of importance for several reasons. The present paper describes an in vivo oncometer developed for this purpose.

A piece of dialysis tubing was filled with a 0.15 M NaCl solution containing 5 g albumin 100 ml‐1. For detecting the hydrostatic pressure inside the tubing, a thin catheter and a silver wire were inserted into it and both ends of the tubing were sealed with glue. The catheter and the silver wire were connected to a servo‐nulling pressure device. The oncometer was then placed under the renal capsule. The pressure inside the dialysis tubing was πonc+ Psc–πsc, and since πonc was known, the net interstitial pressure (Pnet, i.e. Psc–πsc) could be measured continuously in the subcapsular space.

Measurements were made during (1) intravenous bolus injection of 2 ml of 0.9% NaCl, (2) saline expansion of 5% of body weight, and (3) elevation of renal venous pressure to 20 mmHg by clamping the renal vein.

In the control situation, Pnei averaged –3.3 mmHg, a value in good accordance with findings in earlier studies in which the hydrostatic and oncotic pressure components have been measured separately. Following bolus injection of fluid, Pnet increased transiently by 2.6 mmHg, whereas volume expansion produced a permanent increase in Pnei of almost the same magnitude. During elevated renal venous pressure PDei was unaffected, except for a minor increase on clamping and a minor decrease on release of the clamp.

The results show that reproducible and accurate measurements of Pnet in the renal subcapsular space can be made with an in vivo oncometer.
Distension‐dependent changes in noradrenaline sensitivity in small arteries from the rat
Authors: NILSSON HOLGER , SJÖBLOM NINA
Published: December 2008

NILSSON, H. & SJÖBLOM, N. 1985. Distension‐dependent changes in noradrenaline sensitivity in small arteries from the rat.Acta Physiol Scand125, 429–435. Received 5 March 1985, accepted 6 May 1985. ISSN 0001–6772. Department of Physiology, University of Göteborg, Sweden.

The effects of distension on the sensitivity to noradrenaline and potassium were assessed in ring preparations of 200 μM branches from the superior mesenteric artery of the rat. In response to noradrenaline, maximal tension development occurred at smaller luminal diameters than with potassium activation. The sensitivity to noradrenaline increased with increasing distension whereas potassium sensitivity remained largely unchanged. A distension‐dependent increase in noradrenaline sensitivity was observed also in vessels depolarized with high‐potassium solution. The role of the distension‐dependent sensitivity to noradrenaline for isotonic contractions was also studied. Upon activation with applied noradrenaline, submaximal isotonic responses were somewhat smaller than isometric responses at the same dose. This may be ascribed to a reduction in sensitivity during the isotonic contraction. Upon neurogenic activation, no difference between isotonic and isometric responses was found. The results show that distension increases noradrenaline sensitivity in resistance vesselsin vitro, but that the consequences for their function as neuroeffectors may be small.
Effects of noradrenaline on the transcapillary passage of albumin, fluid and CrEDTA in the perfused rat hindlimb
Authors: HARALDSSON BÖRJE
Published: December 2008

HARALDSSON, B. 1985. Effects of noradrenaline on the transcapillary passage of albumin, fluid and CrEDTA in the perfused rat hindlimb. Acta Physiol Scand 125, 561–571. Received 30 January 1985, accepted 30 April 1985. ISSN 0001–6772. Department of Physiology, University of Göteborg, Sweden.

Isolated rat hindlimbs were artificially perfused with serum solutions, either during maximal vasodilatation induced by papaverine or during infusions of noradrenaline (NA) at concentrations of 0.5–3.5 μM. Transcapillary exchange was followed with three independent techniques: (1) clearance of albumin, measured after tissue accumulation of radiolabeled tracer, (2) capillary filtration capacity (CFC), determined gravimetrically, and (3) the capillary diffusion capacity (PS) for CrEDTA, calculated from venous indicator dilution curves after single bolus injection of dyes. During maximal vasodilation, when resistance to flow was 2.3 ± 0.1 PRU100, albumin clearance was 0.0241 ±0.0012 ml min‐1100 g‐1, CFC was 0.0367 ± 0.0009 ml min‐1 mmHg‐1 100g‐1 and PS for CrEDTA was 8.2 ± 0.4 ml min‐1 100 g‐1 Noradrenaline given before radiolabelled albumin increased vascular tone and reduced all three capillary exchange parameters in parallel. Albumin clearance was reduced also when NA was given after the introduction of radiolabeled albumin. When NA raised vascular tone to a level largely corresponding to that in resting skeletal muscle (PRU100 = 14) albumin clearance was 0.0067 ml min‐1 100 g‐1, CFC was 0.0141 ml min‐1 mmHg‐1 100 g‐1 and PS for CrEDTA was 2.4 ml min‐1 100 g‐1. These findings suggest that albumin is transported by convective mechanisms and that the hydrostatic pressures fall in the exchange vessels as a consequence of functional precapillary ‘sphincter’ activity. Further, albumin clearance seems to be the same in the artificially perfused rat hindlimbs as in intact animals, at comparable vascular resistances, suggesting that capillary permeability is not influenced by the present surgical procedure.
Effects of calcitonin on elemental distribution and ultrastructure of rat submandibular gland acinar cells
Authors: SAGULIN GUN‐BRITT , WROBLEWSKI JOANNA , ARVER STEFAN , ROOMANS GODFRIED M.
Published: December 2008

SAGULIN, G.‐B., WROBLEWSKI, J., ARVER, S., & ROOMANS, G.M. 1985. Effects of calcitonin on elemental distribution and ultrastructure of rat submandibular gland acinar cells. Acta Physiol Scand 125, 649–654. Received 22 February 1985, accepted 5 June 1985. ISSN 0001–6772. Departments of Prosthetics, Histology, and Physiology, Karolinska Institute, and Department of Ultrastructure Research, Wenner‐Gren Institute, University of Stockholm, Stockholm, Sweden.

The effect of calcitonin on rat submandibular gland acinar cells was investigated by X‐ray microanalysis and electron microscopy. Calcitonin caused a transient increase of the cellular calcium and magnesium concentration, but did not affect the intracellular concentration of other electrolytes. The relative volume of intracellular mucus increased from 45% in control glands to 72% at 6 h after administration of calcitonin. Calcitonin caused an inhibition of the cellular response of the acinar cells to β‐adrenergic and cholinergic agonists. The changes in elemental composition and ultrastructure of the gland cells are probably due to inhibition of mucus release from the cells.