bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of sodium deoxycholate on morphology, net fluid transport and motility in the small intestine of the rat
Authors: KARLSTRÖM L. , HANSSON G. , JODAL M. , LUNDGREN O.
Published: December 2008

Intestinal fluid secretion and motility were induced by luminal perfusion of rat small intestine with sodium deoxycholate, a dihydroxy bile salt for 1–3 h. Changes in intestinal morphology were studied simultaneously with the changes in fluid transport and motility. The results suggest that the bile salt causes epithelial lesions which may lead to a reduced fluid absorption in the villi, thereby explaining part of the total change in net fluid transport caused by the bile salt. Pyrilamine and indomethacin did not influence the bile salt‐induced secretion. Based on earlier studies, it is proposed that the major part of the bile salt‐evoked secretion is mediated via activation of intramural nervous reflex(es), which also stimulate the intestinal smooth muscle cells.
Effects of a toxic phospholipase A2 (AgTx) from the venom of the Pit viper (Agkistrodon halys (Pallas)) on the crayfish stretch receptor neuron
Authors: RYDQVIST B. , ZHOU J.‐Y. , OTTOSON D. , JIANG M.‐S. , HEILBRONN E. , HAGGBLAD J.
Published: December 2008

Rydqvist, B., Zhou, J.‐Y., Ottoson, D., Jiang, MA, Heilbronn, E. & Häggblad, J. 1987. Effects of a toxic phospholipase A2 (AgTx) from the venom of the Pit viper (Agkistrodon halys (Pallas)) on the crayfish stretch receptor neuron. Acta Physzol Scand130, 299–305. Received 15 October 1986, accepted 22 December 1986. ISSN 0001–6772. Department of Physiology II, Karolinska Institute, and Unit of Neurochemistry and Neurotoxicology, University of Stockholm, Stockholm, Sweden.

Neurotoxicity of an isolated fraction (V) of the venom from the snake Agkistrodon halys (Pallas) was studied on the crayfish stretch receptor using a two‐electrode voltage‐clamp technique. The toxin was previously shown to have less phospholipase A2 activity but to be more toxic in mice compared with bee venom phospholipase A2. At 5 μg ml‐1 (0.35 μM) the AgTx had very little effects on the electrophysiological properties of the receptor neuron whereas at 50 μg m1‐‐1 (3.5 μ) the leak conductance was increased about three times and the net outward (K) current was reduced to 70% of control. The net inward (Na) current was not affected except for a small (+10 mV) shift in the I‐V relationship. The resting membrane potential and the membrane capacitance were not changed by AgTx. These effects of AgTx were similar to those seen after exposure to bee venom phospholipase A, at concentrations 10–20 times lower. At concentrations of AgTx which presynaptically affect the frog neuromuscular transmission (5–10 μg ml‐1) the effects on ion channels in the stretch receptor neuron are very small and probably reflect the low phospholipase A, activity compared with that of bee venom phospholipase A2.
Effects of subacute treatment with toluene on cerebrocorticalα‐and β‐adrenergic receptors in the rat. Evidence for an increased number and a reduced affinity of β‐adrenergic receptors
Authors: FUXE K. , MARTIRE M. , VON EULER G. , AGNATI L. F. , HANSSON T. , ANDERSSON K. , GUSTAFSSON J.‐Å , HARFSTRAND A.
Published: December 2008

Subacute treatment with toluene (80–1500 p.p.m.) produces a dose‐dependent reduction of affinity and increase in density of the β‐adrenergic antagonist [3H]dihydroalprenolol binding sites in the frontoparietal cortex of the male rat, while the binding characteristics of a,‐adrenergic ([3H]WB 4101) and α2‐adrenergic ([3H]p‐aminoclonidine) binding sites in the same region is unaffected by this treatment as evaluatedin vitro. Therefore, it is suggested that the cortical β‐adrenergic receptors are particularly vulnerable to the action of toluenein vivo. It is speculated that as a result cortical β‐adrenergic neurotransmission may be altered following exposure to low concentrations of toluene, possibly related to the physico‐chemical properties of toluene, leading to changes in membrane fluidity.
Brain monoamine metabolism is altered in rats following spontaneous, long‐distance running
Authors: ELAM M. , SVENSSON T. H. , THORÉN P.
Published: December 2008

Brain monoamine metabolism in rats was studied during spontaneous, long‐term running in a microprocessor‐controlled wheel cage. Immediately after heavy spontaneous exercise, DOPA accumulation was decreased in dopamine‐rich brain regions such as the limbic forebrain and corpus striatum, indicating a decreased rate of synthesis of dopamine in brain. In contrast, DOPA accumulation was increased in the noradrenaline‐predominated region of the brain stem, indicating an increased synthesis of noradrenaline in this region. Alterations in brain monoamine metabolism were normalized in exercising animals analysed 24 h after the last running period. Changes in brain monoamine metabolism may be involved in the mechanisms underlying the clinically observed psychological effects of physical exercise.
Differential effect of ganglioside GM1 on rat brain phosphoproteins: potentiation and inhibition of protein phosphorylation regulated by calcium/calmodulin and calcium/phospholipid‐dependent protein kinases
Authors: CIMINO M. , BENFENATI F. , FARABEGOLI C. , CATTABENI F. , FUXE K. , AGNATI L. F. , TOFFANO G.
Published: December 2008

The monosialoganglioside GM1 displays complex effects on protein phosphorylation of rat cerebral cortex membrane preparations. The exogenous ganglioside at a concentration of350, μM in absence of calcium only stimulated the phosphorylation of a protein of MW =64,000. In presence of 1 mM calcium a twofold effect is observed irrespective of the phosphoprotein considered. In particular there is an enhancement of32P incorporation in four major phosphoproteins of MW =160,000, 140,000, 64,000 and50,000 in presence of GM1 compared with that observed with calcium alone. The maximal stimulating effect is achieved with a ganglioside concentration of 35 μm. This effect is inhibited by the addition of 100 μM trifluoperazine (TFP), a phenothiazine known to inhibit calmodulin and protein kinase‐C activities. These four proteins represent the major substrates for the calcium/calmodulindependent protein kinase with the MW =64,000 and50,000 proteins co‐migrating with the autophosphorylated subunits of this enzyme. In addition, the ganglioside inhibited the phosphorylation of three proteins with MW =86,000, 20,000 and14,000. The electrophoretic properties of these phosphoproteins are similar to the autophosphorylated form of protein kinase‐C and to the rat myelin basic proteins, respectively. The effect of the ganglioside on their phosphorylation is not influenced by TFP. Finally, a protein with an apparent molecular weight of46,000 shows also an increased phosphorylation in presence of GM1. The reported results indicate that exogenous GM1 can have profound effects on different kinases such as the calcium/calmodulindependent protein kinase, the protein kinase‐C and also some unknown calcium‐independent protein kinases.
Acute blockade of β1‐receptors in the asphyxiated sheep fetus
Authors: DAGBJARTSSON A. , KJELLMER I. , ROSÉN K. G.
Published: December 2008

Acute blockade of β1‐receptors in the asphyxiated sheep fetus. Acta Physiol Scand 130, 381–385. Received 5 November 1986, accepted 9 February 1987. ISSN 0001–6772. Department of Paediatrics, Landspitalinn, University Hospital, Reykjavik, Iceland and Department of Physiology and Department of Paediatrics I, University of Goteborg, Sweden.

The effects of acute β1‐blockade on fetal cardiovascular reactions during asphyxia were evaluated in 11 exteriorized sheep fetuses. Gestational age was 110–142 days. Asphyxia was induced either by ventilating the mother with low oxygen gas mixture or by mechanical reduction of placental blood flow. During asphyxia all fetuses reacted to metoprolol injection with a decrease in heart rate, myocardial contractility, cardiac output and arterial blood pressure. Five experiments resulted in irreversible fetal cardiovascular collapse. Isoprenaline was given to the fetuses during hypoxia to test the ability to further increase heart rate and activate myocardial β‐adrenoceptors. In those experiments with fetal cardiovascular demise after metoprolol, the isoprenaline injection did not result in a significant tachycardia. The surviving fetuses could increase their heart rate as a sign of a capacity to further increase the sympatho‐adrenergic drive.
Bleeding‐induced decrease in duodenal HCO‐3 secretion in the rat is mediated via α2‐adrenoceptors
Authors: JÖNSON C. , FÄNDRIKS L.
Published: December 2008

Bleeding‐induced in duodenal HCO‐3 secretion in the rat is mediated via α2‐adrenoceptors. Acta Physiol Scand 130, 387–391. Received 23 January 1987, accepted 23 February 1987. ISSN 6001–6772. Department of Physiology, University of Göteborg, Sweden.

This study was performed on chloralosed rats in order to examine the influence of a minor blood loss on duodenal HCO‐3 secretion. The HCO‐3 output was measured by in situ titration in a duodenal segment. Blood loss of 0.6 ml per 100 g body wt (approximately 10% of total blood volume) reduced duodenal HCO‐3 secretion by about 30%. Pretreatment with guanethidine did not affect basal output of HCO‐3 but markedly reduced the bleeding‐induced response. The α2‐adrenoceptor antagonist yohimbine did not affect the basal secretion but almost abolished the depression of duodenal HCO‐3 secretion due to blood loss. Pretreatment with the a,‐adrenoceptor antagonist prazosine or the β‐adrenoceptor antagonist propranolol did neither change basal duodenal HCO‐3 secretion nor the bleeding‐induced decrease in duodenal HCO‐3 secretion. It is suggested that a small blood loss by means of a reflex activation of the sympathetic nervous system, and via the release of transmitter substances from adrenergic nerve endings, reduces the duodenal HCO‐3 secretion. The inhibitory effect is mainly due to activation of α2‐adrenoceptors.
Nervous control of tracheal blood flow in the cat measured by the laser Doppler technique
Authors: MARTLING C.‐R. , GAZELIUS B. , LUNDBERG J. M.
Published: December 2008

Nervous control of tracheal blood flow in the cat measured by the laser Doppler technique. Acta Physiol Scand 130, 409–417. Received 2 December 1986, accepted 9 February 1987. ISSN 0001–6772. Department of Anaesthesia. Karolinska Hospital and Departments of Pharmacology and Endodontics, Karolinska Institute, Stockholm, Sweden.

The tracheal blood flow as determined by the laser Doppler technique was continuously monitored in anaesthetized cats. Electrical stimulation of the right superior laryngeal nerve caused an atropine‐resistant increase in blood flow of the upper trachea. Unilateral vagal nerve stimulation at the cervical level in the presence of atropine induced a frequency‐dependent increase in blood flow of the lower trachea. Intermittent stimulation with bursts of impulses at a high frequency resulted in a considerably larger blood flow increase than a continuous low frequency stimulation giving the same total number of impulses. The ganglionic blocking agent chlorisondamine abolished most of the vagally induced increase in tracheal blood flow when using low threshold parameters (2 V, 0.2 ms) presumably activating preganglionic nerves. High threshold stimulation (10 V, 5 ms) however, still resulted in an increased blood flow suggesting antidromic activation of sensory C fibres. Local mechanical irritation or chemical irritation by capsaicin also increased tracheal blood flow. Furthermore, local application of calcitonin gene‐related peptide on to the mucosa caused a slowly developing, long‐lasting increase in blood flow. Electrical stimulation of the cervical sympathetic trunk and local application of adrenaline reduced tracheal blood flow. In conclusion, vagal nerve stimulation induces an atropine‐resistant increase in tracheal blood flow probably mainly by activating preganglionic parasympathetic nerves and possibly also by antidromic stimulation of C‐fibre afferents.
Lack of casual relationship between medullary blood congestion and tubular necrosis in postischaemic kidney damage
Authors: ANDERSSON G. , JENNISCHE E.
Published: December 2008

Lack of casual relationship between medullary blood congestion and tubular necrosis in postischaemic kidney damage. Acta Physiol Scand 130, 429–432. Received 29 December 1986, accepted 23 February 1987. ISSN 0001–4772. Department of Histology, Gothenburg University, Sweden.

The effect of haemodilution on medullary blood congestion and tubular necrosis was investigated in the rat kidney. Male Sprague‐Dawley rats were subjected to 60 min of unilateral, kidney ischaemia and 24 h of reperfusion. Haemodilution was performed by replacing blood by homologous serum and was done either before induction of ischaemia or during the ischaemic period. Cellular necrosis was evaluated morphologically by a histochemical staining for calcium and a dyeexclusion test. Trapped erythrocytes were visualized by the DAB reaction. It was found that haemodilution could totally prevent medullary congestion. In spite of this, the extent and distribution of necrotic tubular cells in the outer stripe of the outer medulla were the same whether the animal was subjected to haemodilution or not. Our results strongly suggest that the cellular necrosis and the medullary congestion are two separate phenomena occurring at the same time, but without a causal relationship to each other.
Mean power frequency and integrated electromyogram of repeated isokinetic plantar flexions
Authors: GERDLE B. , HEDBERG R. , JONSSON B. , FUGL‐MEYER A. R.
Published: December 2008

Mean power frequency and integrated electromyogram of repeated isokinetic plantar flexions. Acta Physiol Scand 130, 501–506. Received 29 October 1986, accepted 23 February 1987. ISSN 001–6772. Work Physiology Division, National Board of Occupational Safety and Health, and Department of Physical Medicine and Rehabilitation, University of Umeå, Umeå, Sweden.

Peak torque (PT), contraction work (CW), mean power (CP), and time for contraction (t) were recorded for each of 200 full range‐of‐motion repetitive isokinetic (maximum effort) plantar flexions at the preset angular velocity 60 degrees s‐1 (°.s‐1). The subjects were 12 healthy males (42–46 years). Simultaneous recordings of electro‐myographic activity of the three parts of the triceps surae muscle were made. The electromyograms were truly integrated and the mean power frequency was also calculated for each of the contractions. The mechanical variables decreased steeply during approximately the first 70 contractions (the fatigue phase) followed by a steadystate level (the endurance level) with no further significant decrease. The fatigue phase was composed of two parts. The first was characterized by decreases in CW, MPF and in the ratio CW/iEMG, while iEMG and iEMG/t were unaltered. During the second part decreases in iEMG and iEMG/t occurred while MPF and CW/iEMG had stabilized. During the endurance level all the variables were stable but lowered when compared with the initial contractions of the fatigue phase. The results indicated that the mechanical fatigue went through two parts before the steady‐state level was established.
Role of dopamine2‐receptors in mediating renal vascular response to low dose dopamine infusion in the rat
Authors: SERI I. , EKLÖF A. C. , APERIA A.
Published: December 2008

Role of dopamine2‐receptors in mediating renal vascular response to low dose dopamine infusion in the rat.Acta Physiol Scand130, 563–569. Received 6 November 1986, accepted 15 March 1987. ISSN 0001–6772. Department of Developmental Physiology, Karolinska Institute, St Göran's Children's Hospital, Stockholm, Sweden.

The effects of the interaction of dopamine (DA) and the DA2‐receptors on regional blood flows and cardiac output have been studied in the rat. By means of the microsphere technique the blood flow (BF) and vascular resistance (VR) were determined in the kidney, duodenum, spleen, liver, and lung during infusion of DA in the absence and presence of selective DA2‐receptor blockade with S‐Sulpiride (S‐SP), and during infusion of a selective DA2‐receptor agonist (LY‐171555, LY). In order to evaluate the role of the presynaptic DA2‐receptor, the experiments were performed without α‐ and β‐adrenergic blockade. Dopamine was given in such low doses that stimulation of the adrenergic receptors should be negligible. Dopamine, LY and DA + S‐SP did not significantly influence BF and VR in the spleen, liver and lung. Dopamine significantly increased BF and decreased VR in the kidney and the duodenum; LY significantly increased BF in the the kidney but not in the duodenum and decreased VR in both the kidney and the duodenum. In the presence of selective DA,‐receptor blockade, DA did not significantly influence BF or VR in the kidney but in the duodenum BF increased and VR decreased to the same extent as in the absence of blockade. In conclusion; the kidney and the intestine are more abundantly supplied with vascular DA‐receptors than other organs. In the kidney the interaction between DA and the DA2‐receptors significantly contributes the the DA‐induced vasodilation. The interaction between DA and the DA2‐receptors is of less importance for the DA‐induced vasodilatation in the intestine.
Interaction of changes in the third ventricular CSF tonicity, central and systemic AVP concentrations and water intake
Authors: ERIKSSON S. , SIMON—OPPERMANN CH. , SIMON E. , GRAY D. A.
Published: December 2008

Interaction of changes in the third ventricular CSF tonicity, central and systemic AVP concentrations and water intake. Acta Physiol Scand 130, 575–583. Received 23 January 1987, accepted 8 March 1987. ISSN 0001–6772. Max‐Planck‐Institut für physiologische und klinische Forschung, W. G. Kerckhoff‐Institut, Bad Nauheim, FRG and Department of Physiology I, Karolinska Institute, Stockholm, Sweden.

Arginine vasopressin (AVP) is assumed to be involved as a central transmitter or modulator in the control of autonomic functions including thirst. In conscious dogs AVP concentration in cerebrospinal fluid (CSF) from the anterior part of the third ventricle (A3V) was analysed before and after local elevation of CSF osmolality by intracerebroventricular (i.c.v.) infusion of 0.35 m NaCl and after i.c.v. AVP infusion at 46 and 138 fmol ml‐1 for 10 min. In addition, the effects of these i.c.v. infusions on water intake, plasma AVP concentration and blood pressure were investigated. In euhydrated dogs 0.35 M NaCl i.c.v. did not alter AVP concentration in the CSF during the subsequent 2 h. In contrast, plasma AVP concentration had increased significantly from 3.4±0.3 (control) to 6.4 ± 0.7 and 4.7 ± 0.3 fmol ml‐1, 4 and 16 min, respectively, after the hypertonic stimulus. Drinking was stimulated with an average water intake of 14.5 ± 3.7 ml kg‐1 body wt. However, AVP infusion into the A3V did not elicit water intake despite increases of AVP concentration in the A3V by factors up to 40 above control. The same animals responded with spontaneous drinking to 0.35 m NaCl i.c.v. administered 160 min after the end of AVP infusions. Exogenously administered AVP disappeared from the A3V with a time constant of 13.8 min. The results do not support the view that AVP in the A3V CSF per se stimulates drinking.
Mechanisms underlying the small intestinal fluid secretion caused by arachidonic acid, prostaglandin E1 and prostaglandin E2 in the rat in vivo
Authors: BRUNSSON I. , SJÖQVIST A. , JODAL M. , LUNDGREN O.
Published: December 2008

Mechanisms underlying the small intestinal fluid secretion caused by arachidonic acid, prostaglandin E1 and prostaglandin E2 in the rat in vivo. Acta Physiol Scand130, 633–442. Received 15 January 1987, accepted 27 February 1987. ISSN 0001–6772. Department of Physiology, University of Göteborg, Sweden.

Prostanoids were given intraluminally (PGE2) or infused close intra‐arterially (PGE1 and PGE2) or arachidonic acid was administered intraluminally to denervated jejunal segments of the rat in vivo. These experimental manoeuvres caused a net fluid secretion, although a 1000–fold higher concentration of the prostanoids was needed from the luminal than from the vascular side. I.v. hexamethonium or serosally applied lidocaine diminished the induced fluid secretion suggesting that the prostanoids act mainly by eliciting local secretory reflexes in the enteric nervous system. This nervously mediated secretion is not accompanied by any increase in tissue CAMP. However, at higher i.a. concentrations of PGE2 there seems to be a non‐neurogenic effect on the enterocytes associated with an increase in tissue cAMP.
Biological activities of Lipoxin A include lung strip contraction and dilation of arterioles in wiwo
Authors: DAHLÉN S.‐E. , RAUD J. , SERHAN C. N. , BJÖRK J. , SAMUELSSON B.
Published: December 2008

Biological activities of Lipoxin A include lung strip contraction and dilation of arterioles in vivo. Acta Physiol Scand130, 643–647. Received 7 December 1986, accepted 27 February 1987. ISSN 0001–6772. Departments of Physiology and Physiological Chemistry, Karolinska Institute, and Department of Experimental Medicine, Pharmacia AB, Sweden.

Lipoxin A ([5s,6r,15s]‐5,6,15–trihydroxy‐7,9,13–trans‐II‐cis‐eicosatetraenoic acid), a recently characterized lipoxygenation product of arachidonic acid, in submicromolar concentrations elicited long‐lasting contractions of the guinea‐pig lung strip. The response to lipoxin A was not due to release of acetylcholine, histamine, noradrenaline or cyclo‐oxygenase products. 15–hydroperoxyeicosatetraenoic acid (15–HPETE), one precursor of lipoxin A, also contracted the lung strip, but 15–HPETE was less potent and the response was comparatively short‐lived. Furthermore, lipoxin A was inactive on the guinea‐pig trachea whereas 15–HPETE relaxed this preparation. Lipoxin A was also inactive on the guinea‐pig ileum. Intravital microscopy of the hamster cheek pouch disclosed that lipoxin A, as well as 15–HPETE, induced arteriolar dilation but had no effects on microvascular permeability or leucocyte adherence to venular endothelium. Taken together, the leucocyte product lipoxin A displayed a pattern of activity in spasmogenic assays and on the microvasculature that was distinct from those known for prostaglandins, thromboxanes and leukotrienes. The findings indicate that lipoxin A is an additional arachidonic acid derived autacoid with biological actions on smooth muscle in vatro and in vivo.
Actions of some vasodilators on isolated human hand veins
Authors: ARNER M. , HÖGESTÄTT E. D.
Published: December 2008

Actions of some vasodilators on isolated human hand veins.Acta Physiol Scand130, 671–677. Received 7 October 1986, accepted 16 March 1987. ISSN 0001–6772. Department of Hand Surgery, Malmö General Hospital, and Department of Clinical Pharmacology, University of Lund, Sweden.

Vasospasm is a well recognized complication during micro vascular surgery of the hand. In the search for new spasmolytic drug therapies, the effects of papaverine, nitroprusside, nimodipine and lidocaine on isolated human hand veins contracted by several postulated mediators of vasospasm were examined. Mechanical activity was recorded isometrically in ring segments of the vessels. Potassium ions, noradrenaline (NA), 5‐hydroxytryp‐tamine (5‐HT) and prostaglandin F2α(PGF2α) all produced strong contractions that were highly dependent on the presence of extracellular Caa+. Papaverine acted as a non‐selective vasodilator, as it produced an almost identical inhibition of contractile responses to all examined stimulants. Nitroprusside inhibited contractions induced by agonists more than those evoked by K+, whereas the opposite was found for nimodipine. Nitroprusside also seemed to display a certain degree of selectivity among the agonist‐induced responses (NA > PGFaα> 5‐HT). Lidocaine increased the contractile response to K+and at high concentrations (> 10‐‐5M)produced a contractionper se. The clinical efficacy of lidocaine as a vasodilator after topical application therefore seems to reflect an inhibitory action on vasoconstrictor nerves. Papaverine, nitroprusside, nimodipine and lidocaine differ considerably in their profiles of action and therefore deserve to be further evaluated in the treatment of vasospasm during microvascular surgery.
Functional development of the visual system in normal and protein‐deprived rats. IV. Latencies in the specific visual pathway of adult rats
Authors: SJÖSTRÖM A. , CONRADI N. G. , ANDERSSON S. A.
Published: December 2008

Functional development of the visual system in normal and protein‐deprived rats. IV. Latencies in the specific visual pathway of adult rats. Acta Physiol Scand130, 695–703.

It was recently shown that an increase in latency of the cortical visual evoked response (VER) seen in young malnourished animals persists in adult rats given a low protein diet. In the present paper the VER latencies of the specific visual pathway were measured in order to establish the level at which the latency increase occurs in protein‐deprived rats. The VER in the dorsal lateral geniculate nucleus (dLGN) showed no significant differences to onset or peak latencies between control (C) and the protein‐deprived (PD) rats. The dLGN activity was higher in C rats than in PD rats. Late components differed in median values between the two groups, but the individual variations were large. Generally, the VER of the dLGN in PD rats was more stereotype compared with the C rats. Intracortical VER at a depth of 0.4+.5 mm showed a small negative component of short onset latency in both C and PD rats. This component preceded the onset of the initial positivist recorded from the cortical surface by 1–2 ms in C rats and by 3–6 ms in PD rats. Following electical stimulation of the dLGN, no differences in onset latency of the first cortical activity (monosynaptic response) were recorded between C and PD rats, whereas later activity was significantly delayed in PD compared with C rats. The laminar potential pattern was less distinct in PD compared with C rats, and the late components of the evoked response from deep cortical layers were markedly attenuated or lacking. The cortical responses to optic tract stimulation were similar to those of dLGN stimulation, but of an increased latency corresponding to the increase in transmission distance and to the synaptic delay in the dLGN. No increase in synaptic delay through the dLGN was seen in PD rats. The results show that the increased latencies in the cortical surface VER of the PD rats originate mainly from the cortex itself.
Neuropeptide Y and noradrenaline mechanisms in relation to reserpine induced impairment of sympathetic neurotransmission in the cat spleen
Authors: LUNDBERG J. M. , PERNOW J. , FRIED G. , ÄNGGÅRD A.
Published: December 2008

The mechanisms underlying the reserpine‐induced impairment of the functional responses to sympathetic nerve stimulation and output of noradraline (NA) and neuropeptide Y (NPY)‐like immunoreactivity (‐LI) were studied using the isolated blood‐perfused cat spleen. Splenic nerve stimulation (to Hz for 2 min) during control conditions caused perfusion‐pressure increase, volume reduction and an increased output of NA and NPY‐LI. After administration of phenoxybenzamine, the nerve stimulation‐induced perfusion‐pressure increase was almost abolished, the volume reduction inhibited and the output of NPY‐LI enhanced. After subsequent addition of propranolol, a clear‐cut increase in perfusion pressure upon nerve stimulation re‐appeared. Local infusion of NPY caused a potent, long‐lasting, adrenoceptor‐resistant increase in perfusion pressure and a relatively smaller volume reduction of the spleen. Twenty‐four hours after reserpine pretreatment (1 mg kg‐1i.v.), which depleted the splenic content of NA > 95% and NPY‐LI by about 50%, the functional responses upon nerve stimulation were markedly reduced. Preganglionic denervation or pretreament with the ganglionic‐blocking agent chlorisondamine did not influence the NA depletion after reserpine treatment. A considerable, adrenoceptor antagonist‐resistant, long‐lasting functional response as well as a markedly enhanced output of NPY‐LI then occurred upon nerve stimulation. In conclusion, reserpine treatment combined with interruption of preganglionic impulse flow reveals non‐adrenergic, nerve stimulation evoked splenic functional responses which could be mediated by release of a cotransmitter peptide like NPY.
Role of the vagal afferents in substance P‐induced respiratory responses in anaesthetized rabbits
Authors: PRABHAKAR N. R. , RUNOLD M. , Yamamoto Y. , LAGERCRANTZ H. , CHERNIACK N. S. , EULER C. von
Published: December 2008

Since substance P (SP)‐like immunoreactivity has been demonstrated in vagal sensory fibres of bronchopulmonary origin, it was considered of interest to (1) characterize the pattern of responses to SP injected into the pulmonary as well as the systemic arterial system, and (2) assess the types of vagal afferents that are affected by SP. Experiments were performed on 15 pentobarbital‐anaesthetized, spontaneously breathing rabbits. Efferent phrenic nerve activity was monitored as an index of central respiratory neural output. Intra‐atrial injections of SP into the pulmonary circulation (100 ng kg‐1) increased the respiratory rate, and peak integrated phrenic amplitude by 47 ± 8 and 40 ± 4%, respectively, above the controls. In addition, SP elicited augmented breaths (ABs) within 2–3 s in 67% of the trials. In contrast to right atrial injections, no ABs and no significant changes in respiratory rate were observed in response to intra‐aortic injections of SP (100 ngkg–). Tidal phrenic activity rise after aortic injections of SP was significantly less as compared with right atrial administrations of SP. Since both routes of administration decreased the arterial blood pressure to the same extent, these respiratory responses were not likely secondary to cardiovascular changes. After administration of an SP antagonist (d‐Arg‐d‐Trp7.9, Leu11, SP), respiratory responses to SP were significantly attenuated. Also, the rate of occurrence of ABs elicited by releasing the tracheal occlusions was reduced (control 95vs. 14% SP antagonist). Bilateral vagotomy abolished the tachypnoeic response and reduced the magnitude of the phrenic nerve increments caused by right atrial injection of SP. Recordings from vagal sensory fibres showed that SP excites the irritant and C‐fibre receptors of bronchopulmonary origin. It is suggested that SP can excite respiration through its action on pulmonary receptors innervated by vagal nerves.
Blood flow changes in the dental pulp of the cat and rat measured simultaneously by laser Doppler flowmetry and local 125I clearance
Authors: EDWALL B. , GAZELIUS B. , BERG J.‐O. , EDWALL L. , HELLANDER K. , OLGART L.
Published: December 2008

Blood flow changes in the dental pulp of lower canine teeth of mature cats and incisors of mature rats were investigated with simultaneous laser Doppler flowmetry and local 125I‐ clearance (wash‐out) during electrical sympathetic stimulation, efferent stimulation of n. alveolaris inferior (IAN) (cats) and i.a. infusions of substance P (SP) (cats). Stimulation (1–4 Hz, 4 V., 1.5 ms) of the cervical sympathetic trunk produced frequency‐dependent decreases in both laser Doppler output and disappearance rate of iodine tracer from the dental pulp. For the effects of sympathetic stimulation, the correlation (r2) between the results obtained by the two methods was 0.89 (12 observations, six animals). Blood flow measurements by both methods were increased following i.a. infusions of SP (r2= 0.64, six observations, three animals). However, upon stimulation of IAN (10 Hz to V, 5 ms) the laser Doppler flow values showed an increase while the local 125I clearance rate was unaffected or even decreased. The discrepancy between the results obtained following IAN stimulation indicates that the two methods reflect blood flow changes in different parts of the pulpal vascular bed and that the flow is unevenly distributed to these parts during antidromic IAN stimulation. The laser Doppler flowmetry seems to reflect the total blood flow in the coronal pulp and therefore this non‐invasive method may be useful for monitoring blood flow changes in the tooth.
Blood‐to‐tissue transport of albumin in rat fibrosarcomas at two different implantation sites
Authors: HARALDSSON B. , REGNÉR L. , WEISS L. , JANSSON I. , Hultborn R.
Published: December 2008

Albumin clearance and blood flow were measured in normal tissues and in fibrosarcomas by means of a multiple tracer method in intact male rats. Sarcomas implanted in testes had higher albumin clearances than the same tumours implanted in skeletal muscle, 59 and 26 μl min‐1 per 100 g, respectively. Albumin extraction (defined as the ratio of albumin clearance to plasma flow) was found to be 1 times 10–4–14 times 10–4 in normal tissues. Fibrosarcomas in muscle showed high extractions (24 times 10–4), especially in the central portions (96 times 10–4), where the extraction was similar to that in tumours implanted in the testes (111 times 10–4).

The high albumin extraction in poorly perfused central parts of the muscle‐implanted tumours and in the similarly insufficiently perfused testicular sarcomas is probably due to an increased endothelial permeability of the exchange vessels and not to an increased capillary exchange surface area compared with the better‐perfused peripheral parts of the muscle‐implanted tumours. The latter tissue also had a high albumin clearance, however, in the range of that of maximally dilated skeletal muscle vasculature, possibly reflecting a large functional capillary surface area.
Effects of ischaemia on leakage of albumin in rabbit kidneys
Authors: FOLMERZ P. , HANSSON R. , JONSSON O. , LUNDSTAM S. , PETTERSSON S. , RIPPE B. , SCHERSTÉN T.
Published: December 2008

The effect of ischaemia on the leakage of proteins across the vessel walls in rabbit kidneys was studied. The leakage of proteins was estimated from the distribution space of labelled albumin. Various methods to calculate the vascular volume yielding the true extravascular leakage were tested. The most reliable method appeared to be to use the same tracer (131I‐albumin, 125I‐albumin) for both estimating the leakage and the intravascular volume. One hour of ischaemia induced a drastic increase in the extravasation of proteins in the cortex and outer zone of the medulla but not in the inner zone.
Effect of in vivo exposure to insulin on glucose metabolism in rat aorta
Authors: ARNQVIST H. J. , DAHLKVIST H. H.
Published: December 2008

The effect of administration of insulin in vivo on accumulation of [14C]glucose carbon in rat aorta in vitro was studied. Insulin was injected intravenously in a tail vein 5–60 min before the rats were killed and the accumulation of [14C]glucose was determined after incubation for 30–120 min in 5.6 mm [14C]glucose. When determined 30 min after injection of insulin (4 U kg‐1) the aortic [14C]glucose incorporation was significantly increased when an incubation period of 120 min was used, while no significant effect was found after incubation for 30 or 60 min. In subsequent experiments an incubation time of 12o min was used. The aortic [14C]glucose accumulation was not increased when determined 5 or 60 min after injection of insulin (4 U kg–1). Injection of insulin (2 U kg–1) 5 or 30 min before the rats were killed had no effect on the aortic [14C]glucose accumulation but it had a pronounced effect on [14C]glucose accumulation in rat diaphragm. Serum insulin determined 30 min after injection of insulin (2 U kg–1) was 731 ± 58 mU–1 and in saline‐treated control rats 37 ± 3 mU 1–1. These results suggest that the glucose metabolism of vascular smooth muscle has a low sensitivity to the immediate effects of insulin.
Effect of decreased oxygen availability on NADH and lactate contents in human skeletal muscle during exercise
Authors: Katz A. , SAHLIN K.
Published: December 2008

Eight men cycled for 5 min at 120±6 W (x± SE) at which O2 uptake was 50% of its maximal normoxic value, breathing room air (21 % O2; normoxia) on one occasion and 11 % O2 in N2 (respiratory hypoxia/hypoxic — Resp. Hx.) on the other. Biopsies were taken from the quadriceps femoris muscle. Oxygen uptake during exercise was not significantly different between Resp. Hx (1.59±0.08 l min‐1) and normoxia (1.55±0.08 l min‐1). At rest, muscle lactate was the same under both conditions but was four times higher after Resp. Hx (33.2±5.2 mmol kg‐1 dry wt) than normoxic cycling (8.6±1.0 mmol kg‐1 dry wt; P < 0.01). The muscle lactate/pyruvate (which is proportional to cytosolic NADH/NAD) was significantly higher after Resp. Hx. (76±19) than after normoxic cycling (26±2; P < 0.05). At rest, analytically determined NADH averaged 0.14±0.02 mmol kg‐1 dry wt under both conditions. However, exercise during Resp. Hx. resulted in a significantly higher NADH content (0.17±0.01) than exercise during normoxia (0.12±0.01; P < 0.01). Indirect evidence indicates that the difference in muscle NADH reflects a difference in the mitochondrial redox state (Sahlin & Katz 1986). The increased muscle NADH during Resp. Hx. therefore indicates a relative lack of O2 at the cellular level (muscle hypoxia). It is suggested that the increased lactate production during Resp. Hx. is a consequence of the cellular adaptation to muscle hypoxia (i.e. increases in cytosolic ADP, AMP, Pi and NADH).
Twitch contraction for identification of human muscle afferents
Authors: EDIN B. B. , VALLBO Å. B.
Published: December 2008

A classical test to differentiate between Golgi tendon organs and muscle spindles is the twitch contraction elicited by electrical stimulation. The possibility of producing maximal twitches in the finger extensor muscles using surface stimulation over the muscle belly was investigated as well as the feasibility of the test in microneurography experiments. Electrical stimuli were applied either over the muscle in the forearm or the radial nerve in the upper arm, while the resulting torque output at single metacarpophalangeal joints was measured. The relationship between current intensity and maximal contraction force was determined and stimulus response plots were constructed over a large range of current intensities. Stimulation of the radial nerve always yielded plots with a steep and monotonous rising limb up to a plateau. It was concluded that the plateau represented maximal twitch contractions. With transcutaneous stimulation over the muscle belly, the stimulus response plots were usually more complex. However, this could be explained by force transmission through the intertendinous connections on the dorsum of the hand and by antagonist activation. It was concluded that maximal twitch contractions can readily be elicited in the human extensor digitorum muscle with non‐painful transcutaneous electrical stimulations. Moreover, maximal twitches are compatible with single unit recording from muscle afferents in microneurography experiments.
Coexistence of slow and fast isoforms of contractile and regulatory proteins in human skeletal muscle fibres induced by endurance raining
Authors: SCHANTZ P. G. , DHOOT G. K.
Published: December 2008

The distribution of fast and slow isoforms of troponin C, I, and T components and myosin heavy chains was investigated in histochemically typed myofibrillar ATPase intermediate (IM) fibres, that is, fibres that stain after both acid and alkaline pre‐incubation in stainings for myofibrillar ATPase. In addition to the previously described IM fibres of types II C and I B, fibres that displayed staining characteristics between types II C and I B were observed and termed type II C–I B. The IM fibres constitute less than 1% of the fibres in normal human limb and abdominal muscles. The IM fibres studied here resulted from extensive endurance training of human triceps brachii muscle (n= 6) and were induced by conversion of a proportion (130) of type II fibres. The immunohistochemical stains of serial sections with antibodies to slow isoforms of troponin I, T, C and myosin heavy chain showed no staining of type II fibres but intense staining of types I and I B fibres, whereas type II C fibres stained with intermediate intensity. The antibodies to fast isoforms of the troponin components and myosin heavy chain did not give rise to staining of type I fibres but dark staining of type II fibres. Type I B fibres stained with intermediate intensity and type II C was either as dark as type II or slightly lighter. Type II C‐I B fibres showed staining intensities intermediate between those observed for types I B and IIC in the immunohistochemical stains. It is therefore concluded that training‐induced myofibrillar ATPase intermediate human skeletal muscle fibres are characterized by the coexistence of slow and fast isoforms of contractile and regulatory proteins. Changes in the distribution of fast and slow isoforms of several of the myofibrillar proteins appeared to be induced in a co‐ordinated manner.
Fibre types in human lumbar back muscles
Authors: THORSTENSSON A. , CARLSON H.
Published: December 2008

The distribution of histochemically identified muscle fibre types was studied in biopsy samples from the two main muscles in the lumbar region of the human erector spinae, the multifidus and the longissimus, in 16 healthy subjects (nine males and seven females, age 20–30 years). Muscle fibres were classified as types I, IIA, IIB or IIC on the basis of the pH lability of their myofibrillar ATPases. There were no differences between the multifidus and the longissimus muscles in the relative occurrence of type I (62 vs. 57%), type IIA (20 vs. 22%) or type IIB fibres (18 vs. 22%), or in the absolute size of fibres (range of mean least diameters 58–66 μm). The oxidative potential (NADH‐diaphorase staining intensity) was high in type I and low in type II fibres, irrespective of subgroups, in both muscles. In the females, the type I fibres occupied a relatively larger area (70–75 vs. 54–58% for the males) although the relative number of type I fibres was the same in both sexes. This was due to smaller type II fibres in the females resulting in higher type I/type II area ratios (1.70–1.90 vs. 0.88–0.92 for males). This suggests a difference in functional capacity of lumbar back muscles between males and females. On the other hand, the similarity in histochemical fibre‐type distribution between the multifidus and the longissimus muscles does not give support for a functional differentiation between these two anatomically different parts of the lumbar erector spinae in man.
Adaptations to changing speed in human locomotion: speed of transition between walking and running
Authors: THORSTENSSON A. , ROBERTHSON H.
Published: December 2008

The transition speed between walking and running was determined in 18 healthy males (23–38 years) of various statures (range of leg length 0.86–1.09 m) during acceleration and deceleration of different magnitudes (0.05‐0.11 m s‐2) on a motor‐driven treadmill. The speed of the treadmill belt and the duration of the stance phases of each foot were recorded. A transition step was identified and the speed of transition was taken as the average speed value of the stance phase of that step. The overall mean value for the transition speed was 1.88 m s‐1 (range 1.30–2.55). Deceleration resulted in a somewhat lower speed of transition than acceleration. There was a tendency towards increasing values for transition speed with increasing leg length. This could partly be explained by differences in natural frequency. The reasons for the switch between walking and running at a speed which is not extreme for either mode of progression are unclear. The subjective feeling that a transition will lead to a more comfortable situation might be based on previous experience combined with information from peripheral receptors and activity in central networks controlling locomotion.
Effect of Ba2+ and furosemide on K+ and Rb+ secretion and absorption in isolated frog skin
Authors: NIELSEN R.
Published: December 2008

The aim of the present investigation was to explore whether in isolated frog skin there should be different pathways for K+ absorption and secretion. Therefore, the unidirectional fluxes of 42K+ and the K+‐like isotope 86Rb+ were measured. By using various transport inhibitors, separate pathways for active K+ absorption and secretion were detected. The data obtained indicate that the transepithelial K+ and Rb+ transport across isolated frog skin is made up of four different components: one passive and three active. One of the active components is directed from the apical to the basolateral solution, whereas the other two are in the opposite direction. The direction of the net K+ transport depends on the activities of these three active transport components. The active uptake mechanism, which is present in the epithelial cells, discriminates between K+ and Rb+. The ratio between the K+ and Rb+ influxes, K/Rb, is about 3. The presence of Ba2+, furosemide or ouabain in the apical solution had no effect on the K+ influx. The active secretion of K+ takes place via two different pathways, namely the skin glands and the epithelial cells. The K+ secretion via the glands is inhibited by furosemide (basolateral), but is unaffected by Ba2+ (apical) and does not discriminate between K+ and Rb+. The active K+ secretion via the epithelial cells is blocked by apical Ba2+, and it discriminates between K+ and Rb+. The ratio between the K+ and Rb+ effluxes is about z. The data presented show that the K+ channels in the apical and the basolateral membrane of the epithelial cells discriminate between K+ and Rb+. The K+ flux via these channels can be blocked by Ba2+.
Neural control of electrogenic transport in the rat jejunum; interaction between intramural and adrenergic mechanisms
Authors: BUTCHER P. , HEMLIN M. , SJÖVALL H.
Published: December 2008

The aim of the study was to test the hypothesis that extrinsic adrenergic neurons modulate electrogenic ion transport in the jejunum by inhibition of intramural secretory nerve activity. Isolated pieces of rat jejunum were mounted in the Ussing chamber. Noradrenaline (NA) was released from sympathetic nerve endings in the tissue by electrical stimulation of the mesenteric nerves or by the indirect sympathomimetic agent tyramine. Intramural neurons were activated by electrical field stimulation (EFS). Mesenteric nerve stimulation induced a frequency‐related decrease in the transepithelial potential difference (PD) and short circuit current (SCC), effects which were abolished by theα‐adrenergic antagonist phentolamine. A similar response was induced by the serosal application of tyramine and by exogenous NA. Tetrodotoxin (TTX), a nerve conduction inhibitor, had no significant effect on the response to NA, but attenuated the response to tyramine. Both NA and tyramine markedly attenuated the secretory response to EFS, but there was no significant effect of catecholamines on the secretory response to serosal theophylline. The results suggest at least two mechanisms behind the adrenergic modulation of electrogenic chloride secretion: (1) a ganglionic or presynaptic modulation of secretory nerve activity via innervatedα‐receptors, and (2) a modulation at the level of the enterocytes via non‐innervatedα‐receptors. The latter effect does not seem to be mediated by the cAMP system.
β‐adrenoceptor stimulation increases the pH of parotid acinar cells
Authors: JÖNSSON G. , HENRIKSSON R. , LINDSTRÖM P. , SUNDSTRÖM S.
Published: December 2008

To characterize the effect of l‐norepinephrine on intracellular pH (pHi) in parotid acinar cells, we measured the accumulation of 14C‐labelled 5,5‐dimethyloxazolidine‐2,4‐dione ([14C]DMO), in slices of parotid glands from Sprague‐Dawley rats. l‐Norepinephrine enhanced the [14C]DMO uptake in a concentration‐dependent manner with half‐maximal effect at about 1 μ and maximum effect at about 1 mm. The half‐maximal effect corresponded to an increase in pH; by 0.08 units and was reduced by 2 μm l‐propranolol (β‐adrenoceptor antagonist), but was not affected by 2μm phentolamine (α‐adrenoceptor antagonist). The results suggest that l‐norepinephrine increases intracellular pH in rat parotid acini and that this effect may be mediated by β‐adrenoceptor stimulation.