摘要:

SJÖSTRÖM, A., CONRADI, N.G., GUSTAFSSON, B.&WIGSTROM, H. 1985. Functional development of the visual system in normal and protein deprived rats. III: Recordings from adult optic nervein vitro. Acta Physiol Scand,125, 353–358. Received 8 March 1985, accepted 20 April 1985. ISSN 0001–6772. Departments of Physiology and Pathology, University of Goteborg, Sweden.A persistent increase in the latencies of the visual evoked response recorded from the cortical surface of protein deprived adult rats was described recently (SJÖSTRÖMet al.1984). The morphological correlate to this alteration is unknown. Previous studies on malnourished rats have shown a reduction of axonal diameters and in the number of myelin lamellae in relation to axonal circumference, and hence the possibility of a decrease in fibre conduction velocity must be considered. In parallel study, we have established that changes in diameters and myelination of optic nerve fibres similar to those previously reported in malnourished rats are present in adult protein deprived (PD) rats (Conradiel al.1985). In the present paper, recordings of optic nervesin vitrofrom adult normal (C) and protein deprived (PD) rats are described. The compound action potentials were very similar in the two groups. Three positive peaks were easily defined probably corresponding to three functional groups of optic nerve fibers. No significant differences in amplitudes or conduction velocities for the three peaks were found between the C and PD rats. It is concluded that the increased latencies of the evoked response are not caused by a decrease in conduction v

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07729.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SWERUP, C.&RYDQVIST, B. 1985. Effects of halothane on the transducer and potential activated currents of the crustacean stretch receptor.Acta Physiol Scand125, 359–368. Received 20 February 1985, accepted 20 April 1985. ISSN 0001–6772. Department of Physiology II, Karolinska Institute, Stockholm, Sweden.Halothane was applied to the stretch receptor neuron of the crayfish (Astacus astacus) and the effects on the transducer properties and the potential activated currents were studied with potential clamp technique using two microelectrodes. Exposure to halothane reduced the frequency of action potentials during stretch. This was shown to be due to effects both on the action potential generating currents and the transducer current. Halothane partially blocked the TTX sensitive fast inward current in a dose‐dependent manner (Apparent KD= 3 mM). Halothane also reduced the outward current produced by a positive potential step. Both the fast and the slow component were affected, although the fast outward current seemed to be most sensitive. There was little or no change in the currents resulting from negative potential steps. The peak of the receptor potential and the receptor current were very little affected by halothane. The amplitude of the static phase of the receptor potential was reduced to a greater degree than the static phase of the receptor current (cells treated with TTX). A change in reversal potential of about –13 mV was observed for the peak and the static phase of the receptor current in four cells indicating an increased cord conductance for the transducer

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07730.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SAMUELSON, U.E, WIKLUND, N.P.&GUSTAFSSON, L.E. 1985. Dual effects of adenosine and adenosine analogues on motor activity of the human fallopian tube.Acta Physiol Scand125, 369–376. Received 24 January 1985, accepted 20 April 1985. ISSN 0001–6772. Department of Physiology, Karolinska Institute, and National Institute of Environmental Medicine, Stockholm, Sweden.Effects of adenosine and adenosine analogues on spontaneous contractility of the human fallopian tube during different phases of the menstrual cycle were studied. In isthmic preparations, a stimulatory effect by L‐N6‐phenylisopropyladenosine (L‐PIA), with preference for adenosine A1‐receptors, was seen mainly during the proliferative phase. In ampullary preparations, stimulation by L‐PIA was seen both in the secretory and proliferative phases. Adenosine and 2‐chloroadenosine exerted similar stimulatory effects. 5′‐N‐ethylcarboxamide‐adenosine (NECA), with selectivity for adenosine A2‐receptors, or D‐PIA never showed a stimulatory effect. At concentrations above those needed for stimulation, adenosine, 2‐chloroadenosine and L‐PIA inhibited spontaneous contractions, in common with NECA and D‐PIA. Here, NECA was more potent than L‐PIA. The D‐PIA and L‐PIA were equipotent. The inhibition was seen during the whole menstrual cycle. The competitive adenosine antagonist 8‐j>‐sulphophenyltheophylline (PSOT) reversibly antagonized the stimulatory and inhibitory effects elicited by adenosine and the analogues. The PSøT alone could exert a stimulatory or an inhibitory action on spontaneous contractility. We suggest that adenosine can modulate contractile activity in the human fallopian tube via stimulatory A1‐ and inhibitory A2‐ receptors. These receptors are located on the smooth muscle cells, and might act via cAMP. The relative receptor domina

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07731.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

BOBERG, U., MÜLLER‐SUUR, C.&PERSSON, A.E.G. 1985. Renal interstitial pressure measured in the subcapsular space using anin vivooncometer.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 anin vivooncometer 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 πoncwas 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, Pneiaveraged –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, Pnetincreased transiently by 2.6 mmHg, whereas volume expansion produced a permanent increase in Pneiof almost the same magnitude. During elevated renal venous pressure PDeiwas 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 Pnetin the renal subcapsular space can be made wit

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07732.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

EKELUND, M., EL MUNSHID, H.A., HÅKANSON, R.&REHFELD, J.F. 1985. Mechanism of hypergastrinaemia after nephrectomy in the rat.Acta Physiol Scand125, 383–388. Received 17 September 1984, accepted 1 May 1985. ISSN 0001–6772. Departments of Pharmacology and Surgery, University of Lund, Lund, Sweden, and Department of Clinical Chemistry, Rigshospitalet, Copenhagen, Denmark.Bilateral nephrectomy in the rat is followed by hypergastrinaemia and by activation of gastric histidine decarboxylase. The enzyme activity is thought to reflect the concentration of circulating gastrin. While there is general agreement that post‐nephrectomy hypergastrinaemia is primarily the result of loss of renal elimination of gastrin, it remained to be determined whether gastrin secretion could be stimulated in the hypergastrinaemic state and whether it contributed to the hypergastrinaemia. Histamine, but not pentagastrin, is known to evoke gastric acid secretion in the nephrectomized rat, and histamine, but not pentagastrin, was found to lower the serum gastrin level and the gastric histidine decarboxylase activity, indicating that after nephrectomy gastrin was still secreted and that the secretion could be suppressed by increased acid output. The importance of gastrin secretion for post‐nephrectomy hypergastrinaemia was assessed further by investigating the effect of nephrectomy on the serum gastrin concentration in rats previously subjected to operations that had either reduced (e.g. antrectomy) or raised (e.g. antrum exclusion) the serum gastrin concentration. Post‐nephrectomy serum gastrin levels co‐varied with the levels before nephrectomy. Thus, the capacity to secrete gastrin was not abolished by nephrectomy. Finally, nephrectomy greatly affected the linear correlation between the serum gastrin concentration and the gastric histidine decarboxylase activity in a manner suggesting the operation of a gastrin‐independent factor capable of activat

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07733.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

HÄGGBLAD, J., ERIKSSON, H.&HEILBRONN, E. 1985. ATP‐induced cation influx in myotubes is additive to cholinergic agonist action.Acta Physiol Scand125, 389–393. Received 20 March 1985, accepted 1 May 1985. ISSN 0001–6772. Unit of Neurochemistry and Neurotoxicology, University of Stockholm, S‐172–46 Sundbyberg, Sweden.Using biochemical methods, ATP was shown to induce an inward flux of86Rb into cultured chick myotubes. A biphasic dose‐response curve was observed, the first part of which was saturable and had an EC50value of approximately 10 μM. β,γ‐imido ATP inhibited the ATP‐induced uptake. ADP, AMP and adenosine were less potent than ATP in producing influx. ATP‐induced influx of86Rb was found to be additive to carbachol‐induced influx and, in contrast to the latter, not blocked by the nicotinic acetylcholine receptor antagonist α‐bungarotoxin. The results suggest the presence of an ATP recognition‐site on myotube

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07734.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

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 Vo2max 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 Vo2max, 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 Vo2maxto 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‐1at 43%, 61 % and 91 % of Vo2maxThe 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 incre

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07735.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SARM, A., MARTLING, C.‐R., DALSGAARD, C.‐J.&LUNDBERG, J.M. 1985. Evidence for substance P‐immunoreactive spinal afferents that mediate bronchoconstriction.Acta Physiol Scand125, 407–414. Received 7 March 1985, accepted 30 April 1985. ISSN 0001–6772. Department of Experimental and Clinical Pharmacology, University of Graz, Austria, and Departments of Pharmacology and Anatomy, Karolinska Institutet, and Department of Anaesthesiology, Karolinska Sjukhuset, Stockholm, SwedenThe origin and functional role of capsaicin‐sensitive substance P‐(SP‐) immunoreactive (IR) nerve fibres in the lower airways were studied in the guinea‐pig. Stellatectomy caused a significant reduction of SP‐IR in the lung and pulmonary artery. Immuno‐histochemical analysis, however, did not reveal any clear‐cut change in the number and distribution of SP‐IR fibres in the lung of these animals. After combined stellatectomy plus local capsaicin treatment of the vagal nerves, most SP‐IR nerves disappeared in the lower airways. The bronchoconstriction induced by capsaicin was significantly reduced after stellatectomy and abolished after stellatectomy plus capsaicin pretreatment of the vagal nerves. Ether inhalation caused bronchoconstriction, which was not influenced by stellatectomy but markedly reduced by combined capsaicin treatment of vagal nerves and stellatectomy. Stellate ganglion stimulation in animals that had been chemically sympathectomized by 6‐OH‐dopamine caused bronchoconstriction, which was resistant to cholinergic or adrenergic receptor blockade. This response was absent after systemic capsaicin pretreatment, suggesting that it was due to antidromic stimulation of afferent fibres traversing the stellate ganglion. In conclusion, the present data suggest that the lower airways receive SP‐IR capsaicin‐sensitive C‐fibre afferents of both vagal and spinal origin. These sensory fibres seem to have branches both within the bronchial s

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07736.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

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 ofLabrus ossifaguswere 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 com

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07737.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

HELLE, K.B., PIHL, K.E.&SERCK‐HANSSEN, G. 1985. Effects of calcium and limited proteolysis of membrane‐bound and releasable dopamine β‐hydroxylase in adrenomedullary catecholamine granules.Acta Physiol Scand125, 423–427. Received 9 January, accepted 6 May 1985. ISSN 0001–6772. Department of Physiology, University of Bergen, Norway.Bovine chromaffin granules were shown to contain two potent proteolytic systems resulting in limited proteolysis of granule proteins at pH 6.0 in the cold in the presence of inhibitors of serine and thiol proteases. Calcium, whether added during lysis or remaining bound to the lysate protein during dialysis in non‐chelating solutions, enhanced recoveries of total immunoreactive dopamine β‐hydroxylase (14% of total protein) and soluble enzyme (9% of lysate protein) due to degradation of chromogranins. A pepstatin A‐blockable, catepsin D‐like proteolytic system converting membrane‐bound enzyme to its soluble counterpart at pH 6.0 was detected in the gran

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07738.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY