| 21. |
- Andersson, Eva A, et al.
(författare)
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Intramuscular EMG from the hip flexor muscles during human locomotion.
- 1997
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772 .- 1365-201X. ; 161:3, s. 361-70
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Tidskriftsartikel (refereegranskat)abstract
- The purpose was to investigate the activation pattern of five major hip flexor muscles and its adaptation to changing speed and mode of progression. A total of 11 healthy subjects performed walking and running on a motor-driven treadmill at speeds ranging from 1.0 to 6.0 m s-1. Intramuscular fine-wire electrodes were used to record myoelectric signals from the iliacus, psoas, sartorius, rectus femoris and tensor fascia latae muscles. The basic pattern, with respect to number of activation periods, remained the same irrespective of speed and mode of progression. However, differences in the relative duration and timing of onset of activation occurred between individual muscles. Over the speed range in walking, a progressively earlier onset was generally seen for the activation period related to hip flexion. Changes in EMG amplitude were measured in the iliacus and psoas muscles and showed a marked increase and difference between walking and running at speeds above 2.0 m s-1. Thus, the alternating flexion-extension movements at the hip during locomotion appear to be governed by a rather fixed 'neural program' which normally only needs minor modulations to accomplish the adjustments accompanying an increase in speed of progression as well as a change from walking to running.
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| 22. |
- Andersson, Irene, 1978, et al.
(författare)
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Reduced sympathetic responsiveness as well as plasma and tissue noradrenaline concentration in growth hormone transgenic mice
- 2004
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Ingår i: Acta Physiol Scand. - 0001-6772. ; 182:4, s. 369-78
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: Acromegaly [overproduction of growth hormone (GH)] and GH deficiency have both been associated with alterations in autonomic nervous system function. The aim of this study was to investigate autonomic nervous system influence on heart rate (HR) in transgenic mice overexpressing bovine GH (bGH). METHODS: HR and HR variability (HRV) were measured in conscious young (8-13 weeks) and old (5-6 months) female bGH and control mice using telemetry. HR control was studied using antagonists and an agonist of adrenergic and muscarinic receptors. Noradrenaline was measured in plasma, heart and kidney using high performance liquid chromatography. RESULTS: Average 24 h resting HR did not differ between bGH and control mice. After saline injection and after muscarinic blockade with methylscopolamine HR increase was blunted (in old) or absent (in young) bGH mice compared with control mice (P < 0.05). Phenylephrine caused a baroreflex mediated decrease in HR from around 550 to 300-350 beats min(-1), not different between bGH and control mice. Time- and frequency-domain measures of HRV were reduced in old bGH compared with control mice (P < 0.05). Noradrenaline concentrations were reduced by 25-49% in plasma and tissue of bGH compared with control mice (P < 0.05). CONCLUSION: The current study suggests reduced autonomic modulation of HR in bGH transgenic mice. Thus, GH appears to have marked effects on autonomic tone, reducing sympathetic nervous system function possibly via reduced noradrenaline stores.
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| 23. |
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| 24. |
- Andersson, R. M., et al.
(författare)
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Modulation of Na+,K+-ATPase activity is of importance for RVD
- 2004
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772 .- 1365-201X. ; 180:4, s. 329-334
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Tidskriftsartikel (refereegranskat)abstract
- Aim: This study was performed to examine the role of Na+,K+-ATPase activity for the adaptive response to cell swelling induced by hypoosmoticity, i.e. the regulatory volume decrease (RVD). Methods: The studies were performed on COS-7 cells transfected with rat Na+,K+-ATPase. To study changes in cell volume, cells were loaded with the fluorescent dye calcein and the intensity of the dye, following exposure to a hypoosmotic medium, was recorded with confocal microscopy. Results: Ouabain-mediated inhibition of Na+,K+-ATPase resulted in a dose dependent decrease in the rate of RVD. Total Rb-86(+) uptake as well as ouabain dependent Rb-86(+) uptake, used as an index of Na+,K+-ATPase dependent K+ uptake, was significantly increased during the first 2 min following exposure to hypoosmoticity. Since protein kinase C (PKC) plays an important role in the modulation of RVD, a study was carried out on COS-7 cells expressing rat Na+,K+-ATPase, where Ser23 in the catalytic alpha1 subunit of rat Na+,K+-ATPase had been mutated to Ala (S23A), abolishing a known PKC phosphorylation site. Cells expressing S23A rat Na+,K+-ATPase exhibited a significantly lower rate of RVD and showed no increase in Rb-86(+) uptake during RVD. Conclusion: Taken together, these results suggest that a PKC-mediated transient increase in Na+,K+-ATPase activity plays an important role in RVD.
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| 25. |
- Andersson, Sven
(författare)
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Cardiovascular responses to intravenous calcitonin gene-related peptide (CGRP) in the albino rabbit
- 1989
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772. ; 137:2, s. 279-290
-
Tidskriftsartikel (refereegranskat)abstract
- The regional sensitivity of different vascular beds to i.v. CGRP was investigated in the albino rabbit by using the microsphere method. Experiments were performed without pre-treatment on both conscious and pentobarbital-anaesthetized animals. In addition, in one series on conscious animals, rabbits were pre-treated with indomethacin in order to reduce the formation of prostaglandins. In another series, anaesthetized rabbits were subjected to ganglionic blockade with hexamethonium bromide in order to abolish reflexes involving the autonomic nervous system. 120 pmol kg-1 of CGRP was given to all the animals, the conscious animals receiving the peptide in one infusion lasting 4 min. In the anaesthetized animals, the dose was divided into first a 5-min infusion of 30 pmol kg-1 followed some minutes later by a 3-min infusion of 90 pmol kg-1. The most pronounced vasodilatory effects were seen in the pancreas, gallbladder, stomach, duodenum, tongue, teeth and the conjunctiva/nictitating membrane. In some series marked effects were also seen in the dura mater, choroid plexus and some parts of the brain. In the anaesthetized animals almost no statistically significant effects on local blood flows were seen following the first, smaller, dose, but following the larger dose more pronounced effects were observed. Pre-treatment with indomethacin did not to any great extent affect the responses, which contradicts the involvement of prostaglandins. The pattern of the responses was unaffected by the ganglionic blockade, but the variability of response was reduced. In conclusion there are great regional variations in the sensitivity to circulating CGRP. The patterns shows a resemblance to that obtained in other species, but there are some marked differences, The tissues most susceptible to the peptide are those easily exposed to noxious stimuli and containing CGRP in the sensory nerve endings, observations in agreement with the proposed role for the peptide in neurogenic defence mechanisms.
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| 26. |
- Andersson, Sven, et al.
(författare)
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Effects of intravenous calcitonin gene-related peptide (CGRP) and substance P on the blood-aqueous barrier in the rabbit
- 1989
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772. ; 135:3, s. 349-357
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Tidskriftsartikel (refereegranskat)abstract
- The irritation response of the rabbit eye to trigeminal nerve stimulation, which includes a breakdown of the blood-aqueous barrier (BAB), seems to be due to the release of substance P (SP) and calcitonin gene-related peptide (CGRP). In order to assess the relative importance of these two peptides for the barrier effect, and the role of arachidonic acid metabolites (AAM) in the response, we have studied the effects of intravenous injections of the peptides on the permeability of the blood vessels of the anterior uvea and the BAB using labelled albumins. At a dose of 120 pmol kg-1 there was marked leakage of labelled albumin into the aqueous humour in animals under pentobarbital anaesthesia. The leakage was enhanced by sympathotomy. In conscious animals 5 pmol kg-1 CGRP caused enhanced leakage from the blood vessels of the ciliary processes in those pre-treated with biperiden in order to abolish the cholinergic vasoconstrictor tone in the anterior uvea. 24 and 120 pmol kg-1 CGRP caused marked leakage of albumin and a breakdown of the epithelial part of the BAB. These effects were not modified by biperiden pre-treatment, but markedly reduced by pre-treatment with indomethacin. The protecting effect of indomethacin was lost when biperiden was given as well. SP did not cause a leakage with 5 nmol kg-1 and only moderate leakage with 25 nmol kg-1. This effect was abolished by pre-treatment with indomethacin but not if indomethacin was combined with biperiden.(ABSTRACT TRUNCATED AT 250 WORDS)
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| 27. |
- Andersson, Sven
(författare)
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Effects of intravenous calcitonin gene-related peptide (CGRP) on local blood flow in the cat
- 1989
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772. ; 137:2, s. 259-270
-
Tidskriftsartikel (refereegranskat)abstract
- The effects of i.v. calcitonin gene-related peptide (CGRP) on regional blood flow, vascular resistance, heart rate and cardiac output in cats were studied using the microsphere method. Three series of experiments were performed. In the first there was no pre-treatment of the animals. In the second the animals were pre-treated with indomethacin (5 mg kg-1) in order to prevent the formation of prostaglandins. In the third series the ganglionic blocking agent hexamethonium bromide (80 mg kg-1) was given in order to prevent autonomic reflexes. CGRP was given as an i.v. infusion. Two doses were tested in each series. Animals with no pre-treatment and those pre-treated with indomethacin received first 60 pmol kg-1 infused over a 5-min period and then 180 pmol kg-1 infused over a 3-min period. Animals under ganglionic blockade received the same dose as the total infusions in the other series (240 pmol kg-1) infused over 4 min and a second infusion of 1.2 nmol kg-1 over 5 min. Vasodilatory effects were observed in most of the tissues tested, but there were marked differences in sensitivity. The most sensitive tissues seemed to be the lacrimal, submandibular and parotid glands, the nictitating membrane, the tongue and the gallbladder. The patterns of sensitivity were similar in all the series, indicating that neither prostaglandins nor autonomic reflexes were involved in the effects. In experiments with animals under ganglionic blockade, an increase in blood pressure, concomitant with an increase in heart rate, was seen 5 min after the infusions ended. Thus, it is likely that the peptide exerts a direct positive chronotropic effect on the feline heart.
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| 28. |
- Andersson, Sven, et al.
(författare)
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The effect of endothelin receptor blockade on the development of the Sephadex-induced inflammation in the rat lung
- 1996
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772. ; 158:2, s. 189-193
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Tidskriftsartikel (refereegranskat)abstract
- The non-peptide ET-receptor antagonist Bosentan was used to investigate the role of endogenous endothelin-1 (ET-1) in the development of the Sephadex-induced lung inflammation in the rat. Intratracheal instillation of Sephadex caused a 60-fold rise in endothelin-1-like-immunoreactivity (ET-1-LI) in bronchoalveolar lavage fluid (BALF) concomitant with development of lung oedema, an influx of inflammatory cells into the airways and a rise in the protein content in BALF. The ET-1-LI level in lung homogenate was not significantly affected. Pre-treatment with Bosentan reduced ET-1-LI content in the lung parenchyma but increased ET-1-LI levels in BALF, possibly indicating an effective displacement of ET-1 from its receptors. In Bosentan-treated animals there was an enhancement of the lung oedema formation following Sephadex instillation, but no significant change in the number of leucocytes or protein concentration in BALF. The present data thus do not support the hypothesis that endogenous ET-1 mediates oedema formation or leucocyte influx in this model. If anything, Bosentan enhanced the oedema formation in parallel with increased ET-1-LI in BALF.
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| 29. |
- Andersson, Staffan, et al.
(författare)
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Wall mechanics of the rat bladder. I. Hydrodynamic studies in the time domain.
- 1988
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772 .- 1365-201X. ; 134:4, s. 457-461
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Tidskriftsartikel (refereegranskat)abstract
- The hydrodynamic properties of the rat bladder in the collection phase were examined by slow continuous and very fast stepwise cystometry in nine rats. In vivo, the fast volume steps induced a reproducible detrusor contraction (type A) which remained after spinal anaesthesia and anticholinergic treatment, but ceased post-mortally within 1 h. No significant effect of anticholinergic treatment was found on bladder stiffness. The stiffness and relaxation time of the bladder wall increased markedly at large distension. At small and moderate distension, however, the compliances evaluated from continuous and stepwise cystometry were nearly the same, and a linear elastic model of the bladder was applicable. We consider that the rat bladder will be a useful experimental model in further research on viscoelasticity and instability of the bladder wall.
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| 30. |
- Andersson, Staffan, et al.
(författare)
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Wall mechanics of the rat bladder. II. Hydrodynamic studies in the frequency domain
- 1988
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772 .- 1365-201X. ; 134:4, s. 463-466
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Tidskriftsartikel (refereegranskat)abstract
- The hydrodynamic properties of the urinary bladder in rat were examined by means of very small periodic changes in volume at different frequencies. The elastance increased with increasing frequency of volume changes, indicating the presence of viscoelastic elements. When the bladder was only moderately distended the influence of viscosity was minor. We consider that the rat bladder examined by this technique is an ideal experimental model for assessment of in vivo effects of pharmacological agents on bladder wall tonus. For example, cholinergic treatment showed a 100% increase in elastance and atropine inhibited this effect completely within 3 min.
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