bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sympathetic vascular control of the pig nasal mucosa: (I) increased resistance and capacitance vessel responses upon stimulation with irregular bursts compared to continuous impulses
Authors: LACROIX J. S. , STJÄRNE P. , ÄNGGÅRD A. , LUNDBERG J. M. 
Published: December 2008

An in vivo model is described in which pentobarbital anaesthetized pigs were used to study the sympathetic nervous control of the nasal mucosal vascular bed. Changes in blood flow in the sphenopalatine artery (representing nasal blood flow) and in the volume of the nasal cavity (mainly reflecting blood content in venous sinusoids), upon electrical stimulation of the cervical sympathetic trunk, were recorded simultaneously. Single impulses (15V, 5 ms) reduced both the arterial flow and the volume of the nasal mucosa. The effects of nerve stimulation with a continuous train of impulses at 0.59, 2 and 6.9 Hz were compared with those caused by stimulation with the irregular bursting pattern, triggered by recorded human sympathetic vasoconstrictor nerve activity, with the same average frequencies. Both types of stimulation reduced nasal blood flow and volume, but the responses were significantly larger with burst stimulation at 0.59 Hz. The volume reduction was already maximal at 0.59 Hz while the blood flow response increased further higher frequencies. Local intra‐arterial pretreatment with the α‐adrenoceptor antagonist phenoxybenzamine significantly attenuated the flow and volume responses to single impulses, while clear‐cut reductions in blood flow (by 40%) and volume (by 80%) remained, upon stimulation, at 6.9 Hz. Noradrenaline given intra‐arterially caused a dose‐dependent reduction in nasal blood flow and volume. The noradrenaline effects were blocked by phenoxybenzamine treatment.The results show that the pig nasal mucosa represents a model where both blood flow and volume changes can be studied in parallel in vivo. Furthermore, stimulation with the firing pattern of human vasoconstrictor nerves, i.e. irregular bursts, causes larger vascular responses in the pig nasal mucosa compared to a continuous stimulation. The large residual vascular responses to sympathetic nerve stimulation at high frequency after a‐adrenoceptor blockage may be mediated by some other non‐adrenergic transmitter substance(s).
Differing expression of insulin‐like growth factor I in the developing and in the adult rat cerebellum
Authors: Andersson I. K. , EDWALL D. , NORSTEDT G. , ROZELL B. , SKOTTNER A. , HANSSON H.‐A. 
Published: December 2008

Insulin‐like growth factor I (IGF‐I; somatomedin C) is a trophic peptide of importance for the development of several tissues and organs. In the present study we have mapped the cellular distribution and dynamic changes of IGF‐I immunoreactivity in the rat cerebellum from its postnatal development to maturity. In vitro hybridization of IGF‐I mRNA was used to demonstrate that the IGF‐I immunoreactive material was synthesized in the cerebellum during a limited time period of cerebellar differentiation.IGF‐I immunoreactivity was absent in primordial nerve cells but was present in neuroglial cells during the first two days after birth and then rapidly increased in intensity in the latter during the next few days. Proliferative nerve cells in the external granular layer did not express IGF‐I immunoreactivity, while migrating and differentiating nerve cells as well as neuroglial cells showed intense labelling. Starting about 2 weeks postnatally, the IGF‐I immunoreactivity declined, first in the neuroglial cells and eventually in the nerve cells. No IGF‐I immunoreactivity could be demonstrated in the normal adult cerebellum. Colchicine pretreatment did, however, enable demonstration of IGF‐I immunoreactivity in adult cerebellar nerve cells but not in neuroglial cells. In vitro hybridization revealed IGF‐I mRNA in the developing cerebellum but only at very low levels in the adult cerebellum.It is concluded that IGF‐I is likely to be a factor of importance for the development and maturation of nerve cells and neuroglial cells in the brain. The neuroglial cells in normal adult cerebellum as well as in other parts of the central nervous system do not show any IGF‐I immunoreactivity, in contrast to neuroglial cells in the automatic and peripheral nervous systems.
Contractile properties during development of hypertrophy of the smooth muscle in the rat portal vein
Authors: MALMQVIST U. , ARNER A. 
Published: December 2008

Department of Physiology and Biophysics, University of Lund, SwedenStructural and mechanical alterations during hypertrophy of the rat portal vein were investigated. Growth of the vessel was induced by a partial ligature of the vessel causing an increased transmural pressure. Vessel segments from animals kept with ligature for 1, 3, 5 and 7 days, were compared with vessels from sham‐operated animals. Maximal active force and vessel cross‐sectional area increased with time in the ligated group. On day 7, force and cross‐sectional area at the optimal length, were markedly increased in the ligated group (21.1 ± 1.0 mN, 0.55 ± 0.04 mm2,n= 9) compared with the control vessels (11.7 ± 1.0 mN, 0.30 ± 0.02 mm2,n= 7). Light and electron microscopy of preparations fixed at optimal length showed that the amount of smooth muscle and the cross‐sectional area of cell profiles were almost doubled in the ligated group on day 7, consistent with hypertrophy of the smooth muscle. The force per smooth muscle cell area was similar in the two groups (ligated: 132 ± 15; control: 145 ± 16 mN mm‐2,n= 4–5). The maximal shortening velocity was significantly lower in the hypertrophied group (ligated: 0.28 ± 0.02;control: 0.41 ± 0.01 optimal length s‐1,n= 6). In chemically skinned preparations, activated by maximal thiophosphorylation of the myosin light chains, force was higher in the ligated group compared to the controls but no difference in maximal shortening velocity was observed. In conclusion, the increased transmural pressure is associated with a rapid increase in the amount of smooth muscle in the portal vein. The mechanical data show that after 7 days the force generating ability of the contractile system has increased in proportion to the smooth muscle cell mass. The unaltered maximal shortening velocity in the skinned hypertrophied preparations suggests that the kinetic properties of the maximally activated contractile system are unaltered. The decreased maximal shortening velocity in the intact hypertrophied preparations may reflect alterations in the excitation‐contraction coupling.
Vagally mediated vasodilatation by motor and sensory nerves in the tracheal and bronchial circulation of the pig
Authors: MATRAN R. , ALVING K. , MARTLING C. R. , LACROIX J. S. , LUNDBERG J. M. 
Published: December 2008

A newin vivomodel is described in which anaesthetized pigs were used to study vascular responses in the bronchial, upper tracheal and laryngeal circulation upon electrical stimulation of the vagal or superior laryngeal nerves. Vagal or superior laryngeal nerve stimulation increased blood flow in the bronchial artery and the superior laryngeal artery, respectively. After pre‐treatment with atropine the vasodilatory response in the bronchial artery upon stimulation was not modified while the increase in blood flow in the superior laryngeal artery was reduced. The ganglionic blocking agent chlorisondamine further reduced the nerve stimulation evoked decrease in vascular resistance in the superior laryngeal artery, but did not influence the response of the bronchial artery. Capsaicin induced a marked increase in blood flow both in the bronchial and superior laryngeal arteries after pre‐treatment with atropine, guanethidine and chlorisondamine. After capsaicin tachyphylaxis, the vasodilatation upon nerve stimulation in the bronchial artery and the smaller remaining decrease in vascular resistance in the superior laryngeal artery were strongly reduced. Thus, antidromic stimulation of afferent C fibres may increase blood flow via release of vasodilatory peptides such as tachykinins and calcitonin gene‐related peptide.The present findings show that local blood flow in the larynx and upper trachea is regulated by cholinergic and non‐cholinergic parasympathetic mechanisms and a small capsaicin sensitive, sensory component. On the other hand, the vagal control of the bronchial circulation seems to exclusively involve capsaicin sensitive sensory nerves.
The influence of the pelvic nerves on. anorectal motility in the cat
Authors: CARLSTEDT A. , NORDGREN S. , FASTH S. , HULTEN L. 
Published: December 2008

The influence of the parasympathetic pelvic nerves on anorectal motility was studied in anaesthetized cats. Anal pressure and rectal motility were recorded by a manometric and a volumetric method, respectively. Severing of the pelvic nerves did not cause any pressure change in the anus, indicating that these nerves are not significantly tonically active. Efferent low intensity (0.05–0.5 ms, 8 V at 5 Hz) electrical stimulation of the pelvic nerves (PNS) elicited a contraction of the internal anal sphincter (IAS), while high intensity stimulation (> 1 ms, 8 V at 5 Hz) caused a sphincter relaxation. A rectal contraction was noted on both low and high intensity stimulation. After sectioning of the sympathetic nerves, PNS elicited a contraction in both the anus and the rectum irrespective of stimulation intensity. PNS inhibited the anal contraction elicited by simultaneous stimulation of the sympathetic nerves or noradrenaline infusion. The inhibitory anal responses to PNS were unaffected or augmented by atropine, unaffected by propranolol and abolished by hexamethonium. The excitatory anal effects of PNS were reduced or abolished by atropine and abolished by phentolamine. The rectal contraction induced by low intensity PNS was abolished by atropine or converted to a relaxation. In half of the experiments an atropine resistant rectal contraction was observed in response to high intensity PNS.The results are consistent with a pelvic nerve influence on IAS pressure through several mechanisms, including modulation of the activity in the sympathetic nerves and activation of inhibitory non‐adrenergic, non‐cholinergic neurons. The pelvic nerves convey both cholinergic and non‐cholinergic excitatory, as well as non‐adrenergic, noncholinergic inhibitory fibres to the rectum.
Ground reaction forces at different speeds of human walking and running
Authors: NILSSON J. , THORSTENSSON A. 
Published: December 2008

In this study the variation in ground reaction force parameters was investigated with respect to adaptations to speed and mode of progression, and to type of foot‐strike. Twelve healthy male subjects were studied during walking (1.0–3.0 m s‐1) and running (1.5–6.0 m s‐1). The subjects were selected with respect to foot‐strike pattern during running. Six subjects were classified as rearfoot strikers and six as forefoot strikers. Constant speeds were accomplished by pacer lights beside an indoor straightway and controlled by means of a photo‐electronic device. The vertical, anteroposterior and mediolateral force components were recorded with a force platform. Computer software was used to calculate durations, amplitudes and impulses of the reaction forces. The amplitudes were normalized with respect to body weight (b.w.). Increased speed was accompanied by shorter force periods and larger peak forces. The peak amplitude of the vertical reaction force in walking and running increased with speed from approximately 1.0 to 1.5 b.w. and 2.0 to 2.9 b.w. respectively. The anteroposterior peak force and mediolateral peak‐to‐peak force increased about 2 times with speed in walking and about 2–4 times in running (the absolute values were on average about 10 times smaller than the vertical). The transition from walking to running resulted in a shorter support phase duration and a change in the shape of the vertical reaction force curve. The vertical peak force increased whereas the vertical impulse and the anteroposterior impulses and peak forces decreased. In running the vertical force showed an impact peak at touch‐down among the rearfoot strikers but generally not among the forefoot strikers. The first mediolateral force peak was laterally directed (as in walking) for the rearfoot strikers but medially for the forefoot strikers.Thus, there is a change with speed in the complex interaction between vertical and horizontal forces needed for propulsion and equilibrium during human locomotion. The differences present between walking and running are consequences of fundamental differences in motor strategies between the two major forms of human progression.
Intracellular ion exchange between cytoplasmic potassium and granule histamine, an integrated link in the histamine release machinery of mast cells*
Authors: UVNÄS B. , ÅBORG C.‐H. , LYSSARIDES L. , DANIELSSON L.‐G. 
Published: December 2008

Rat peritoneal mast cells isolated by gradient centrifugation in Percoll were placed between two membrane filters in a Sartorius filter apparatus and superfused with isotonic balanced salt solutions or with deionized isotonic sucrose. Histamine was released according to ion exchange kinetics. Our explanation of the observed phenomena is as follows. The superfusion induces a flow of cytoplasmic K+ions across the histamine‐containing granules, resulting in an ion exchange K+←Hi+ions at the histamine binding sites. The concomitant equimolar outflow of histamine and potassium is considered to be due to a functional interplay between two histamine pools, a release and a donor pool. As the result of the K+←SHi+ion exchange at the histamine binding sites of the release pool, these sites become transiently occupied by K+ions only to be immediately reoccupied by Hi+ions from the donor pool. The observed equimolar outflows are consistent with a 1/1 molar ratio in the exchange between histamine and potassium ions.The essential role of cytoplasmic potassium in the histamine release mechanism is a new and important observation with possible implications not only as to histamine release in general (including so‐called ‘spontaneous’ histamine release) but also as to the release of biogenic amines and other positively charged substances stored in granules in ionic linkage to the matrix.
Omeprazole: inhibitor of both acid formation and translocation in gastric mucosa
Authors: EKBLAD E. B. M. 
Published: December 2008

Ekblad, E. B. M. 1989. Omeprazole: inhibitohd of both acid formation and translocation in gastric mucosa.Acra Physiol Scand137, 223–230. Received 15 March 1989, accepted 2 June 1989. ISSN 0001–6772. Cardiovascular Research Institute, University of California, San Francisco, and Nephrology, Veterans Administration Medical Center, San Francisco, CA, USA.Omeprazole, believed to inhibit H+, K+‐ATPase, was used to study acid secretion dynamics in isolated gastric mucosa. Tissue was mounted in a chamber and continuously supplied with both fresh nutrient and secretory solution (flow‐through). Acid secretion was monitored on and recorded by a pH‐stat microprocessor set‐up. In spontaneously secreting mucosa the continuous presence of omeprazole causes a monotonic decline in secretion rate to a new lower steady state. The relationship between the inhibited steady‐state acid secretion rate and omeprazole concentration is expressed by the sum of two hyperbolic functions withK1s differing by a factor of more than 100. When omeprazole is removed, the secretion rate always recovers. The amount of acid suppressed depends uniquely on omeprazole exposure: it is proportional to the exposure at low exposure and disproportionate (logarithmic) at high exposure. The index of conservation declines with omeprazole exposure, i. e. the inhibition by omeprazole ranges from conservative (no net loss of acid) to non‐conservative (net loss of acid). Dithiothreitol causes the inhibition by omeprazole to be conservative (index of conservation = 0) at even higher omeprazole exposure. The index of conservation was introduced to allow for numerical evaluation of both inhibitory and stimulatory effects regardless of the magnitude of the effect. It is concluded that omeprazole acts at two different sites, possibly with inhibition by sulphoxide derivatives on the formation step and sulphide derivatives on the translocation step.,
Cardiovascular responses to intravenous calcitonin gene‐related peptide (CGRP) in the albino rabbit
Authors: ANDERSSON S. E. 
Published: December 2008

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‐1of 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‐1followed some minutes later by a 3‐min infusion of 90 pmol kg‐1.Thde most pronounced vasodilatory effects were seen in thhd 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.,
Interaction between sympathetic nerve fibres and epithelial transport in the rat jejunal mucosain vivo
Authors: HEMLIN M. 
Published: December 2008

The aim of this study was to elucidate the mechanisms behind the absorptive response to mesenteric nerve stimulation (MNS). Segments of rat jejunum were mounted with intact blood circulation in an‘in‐vivochamber’, allowing parallel registration of net fluid transport rate (NFT) and electrical parameters of the tissue. All segments secreted fluid spontaneously, and the secretion rate was inversely correlated to the corresponding potential difference (PD) across the segment. The secretion was not inhibited by atropine. The nicotinic antagonist hexamethonium (Hx) inhibited the secretion and changed the relationship between PD and NFT. MNS reversed the secretion into an absorption (absorptive response) and decreased PD and short‐circuit current (SCC) (electrogenic response). Total tissue resistance (Rt) was not significantly changed. The absorptive response increased at high control secretion rates and the electrogenic response increased at high control PD levels. The electrogenic response was inversely related to the absorptive response; however, the presence of Hx reversed this correlation. Guanetbidine, a sympatholytic agent, eliminated all effects of MNS. Phentolamine eliminated the absorptive response but not the electrogenic response, and the remaining electrogenic response was not sensitive to propranolol (a β‐adrenergic antagonist). Hx induced similar but smaller effects than MNS, and after Hx treatment the MNS effects were reduced. We conclude:Fluid secretion in our model involves a mechanism other than electrogenic Cl‐secretion.MNS activates sympathetic nerve fibres, which enhance fluid absorption and decrease PD and SCC.The absorptive and electrogenic responses involve partly separate transport mechanisms.Both responses are partly due to the inhibition of intramural secretory nervous pathways.Some sympathetic nerve fibres interact directly with the epithelium.
Neuromuscular actions of endothelin on smooth, cardiac and skeletal muscle from guinea‐pig, rat and rabbit
Authors: WIKLUND W. P. , ÖHLÉN A. , WIKLUND C. U. , CEDERQVIST B. , HEDQVIST P. , GUSTAFSSON L. E. 
Published: December 2008

The peptide endothelin (human, porcine) was investigated for effects on basal muscle tone and on responses to transmural nerve stimulation in a series of smooth muscle preparations, as well as in guinea‐pig atrium and rat and guinea‐pig diaphragm. Endothelin lacked effect on basal tone or on spontaneous and electrically driven contractions in skeletal and atrial muscle. It contracted guinea‐pig ileum, pulmonary and femoral arteries, rat anococcygeus, vas deferens and urinary bladder and rabbit taenia coli, whereas guinea‐pig taenia was relaxed. Guinea‐pig urinary bladdcr and vas deferens and rabbit iris sphincter were unaffected up to 3 × 10‐‐8M. Endothelin thus has a unique pattern of smooth muscle effects, exhibiting mostly contractile hut also relaxing effects.Endothelin modified contractile responses to transmural nerve stimulation, yielding marked and persistent enhancement, in guinea‐pig and rat vas deferens, and enhancement also in guinea‐pig pulmonary artery. In guinea‐pig and rat vas deferens the response to exogenous ATP was increased by endothelin, thus suggesting a strong post‐junctional enhancement of neurotransmission. In guinea‐pig ileum nerve‐induced responses were inhibited by endothelin, whereas exogenous acetylcholine was enhanced, an effect suggesting a simultaneous pre‐junctional inhibition and post‐junctional enhancement.The Ca2+channel blocker felodipine counteracted the stirnulatory effects of cndothelin on tone and transmurally induced contractions. Tachyphylaxis to cndothelin action was sometimes evident, but the anococcygeus being less prone to this might be useful for studies on endothelin antagonism. Endothelin thus has prominent post‐junctional, and also probably pre‐junctional, effects, lcnding further support for a distinct biological role of this peptide.