bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Colchicine, Vinblastine and Vincristine on Degeneration Transmitter Release after Sympathetic Denervation Studied in the Conscious Rat
Authors: Lundberg Dag 
Published: December 2008

AbstractThe effect of the mitosis inhibitors colchicine, vinblastine and vincristine on the time course of the degeneration contraction of the sympathetically innervated periorbital smooth muscle was studied in conscious rats. In conformity with earlier findings with colchicine, single s.c. doses of vinblastine (2–4 mg/kg) or vincristine (1–2 mg/kg) given at the time of axotomy delayed the start of the degeneration contraction,i.e. the leakage of sympathetic transmitter from the degenerating nerve endings. The significance for the delaying effect of the time interval between axotomy and injection of colchicine was studied in some detail. The delaying effect declined gradually with increasing time interval between denervation and injection. Colchicine given later than 4–6 h after axotomy did not delay. In view of this finding and the fact that the mitosis inhibitors used are known to inhibit the intra‐axonal microtubular transport of different nerve constituents it is proposed that the drugs postpone the degeneration transmitter release by slowing down the rate by which an “axotomy information” is transported distally along the neuron. The “axotomy information”, probably linked to some axotomy‐induced change in intra‐axonal structures related to the microtubules, seems to be transported at a rate of about 4 mm per hr. Local treatment of the decentralized superior cervical ganglion with colchicine or vinblastine induced a “degeneration” contraction probably due to a complete inhibition of the flow of some vital matter to the nerve endings.
Studies on Left Ventricular Receptors, Signalling in Non‐Medullated Vagal Afferents
Authors: ÖBerg Bengt , Thorén Peter 
Published: December 2008

AbstractLeft ventricular receptors, signalling in non‐medullated vagal fibres and displaying a low, irregular spontaneous activity, have been analysed by recordings of impulse activity in cardiac afferent nerves. The receptors were distributed diffusely all over the ventricle and in both superficial and deep layers of the myocardium. They were activated by occlusions of the ascending aorta, by substantial elevations of arterial blood pressure and by rapid infusions of saline or dextran, whenever these procedures produced a clearcut increase of intraventricular diastolic pressure and end‐diastolic volume. The endings were also excited by veratrum alkaloids, nicotine and digitalis alkaloids. When activated, the receptors usually displayed a cardiac rhytm, but with intense stimulation the activity usually became continuous. The receptors evidently function as mechano‐ or deformation receptors, responding primarily to a distension of the ventricle. Activation of the receptors causes a reflex bradycardia and, in all probability, vasodilatation and blood pressure fall. They may contribute to the homeostatic control of blood pressure and blood volume, but their main function seems to be to protect the heart frome.g. imminent overloading. The endings are probably of main importance for the emergence of the Bezold‐Jarisch reflex.
Intracranial Pressure in Conscious Rabbits after Decentralization of the Superior Cervical Sympathetic Ganglia
Authors: Edvinsson L. , Owman Ch. , West K. A. 
Published: December 2008

AbstractThe intracranial pressure, measured as the ventricular fluid pressure, was recorded continuously during about 2 days in conscious rabbits at various time‐periods after bilateral decentralization (preganglionic denervation) of the superior cervical sympathetic ganglia. The pressure recorded 5 h after the operation was initially unchanged compared with non‐denervated control animals. During the following day it increased by approximately 50 mm physiological saline. The pressure was elevated (by approximately 25 mm saline) also 6 days after the operation. At 2 weeks it had returned to almost the same level as in the non‐denervated controls. It is suggested that the alterations in the ventricular fluid pressure mainly reflect changes in the cerebral blood volume, although direct effects on the sympathetically supplied choroid plexuses cannot be excluded.
Hemodynamic Responses of Relaxed and Shivering Hypothermic New‐Born Lambs
Authors: Koivikko Antti , Lånsimies Esko 
Published: December 2008

AbstractThe hemodynamic responses to hypothermia and shivering were investigated in 4 relaxed, in 9 deeply anesthetized and 9 lightly anesthetized new‐born lambs. Muscle‐relaxation and deep anesthesia prevented the increases of the oxygen consumption and the cardiac output. In shivering lambs these parameters increased. Correction of metabolic acidosis increased temporarily the cardiac outputs. The cardiac responses to cold stress of the relaxed and deeply anesthetized lambs differed from that seen in the relaxed adult dogs but were similar to those observed in relaxed, β‐blocked dogs. This difference may be due to some kind of immaturity of the β‐adrenergic system in the new‐born period.
The Pressure‐Flow Relationship in Renal Cortical and Medullary Circulation
Authors: Grängsjö G. , Wolgast M. 
Published: December 2008

AbstractThe perfusion pressure‐red cell flow relationship in the cortical and in the outer and inner medullary circulation has been investigated on 9 chloralos anesthetized mongrel dogs using an indicator‐dilution technique with 32‐P labelled red cells and internal detection with small needle‐shaped semiconductor detectors. The perfusion pressure was varied by a clamp on the aorta. High pressures were obtained by ligation of the carotid arteries and section of the vagal nerves preceded by denervation of the renal nerves. The change in red cell flow on changing the perfusion pressure was determined from 1. the change in the regional mean transit time and 2. the change in regional red cell volume. The flow in all the regions studied was then found to be lineary related to the perfusion pressure up to some 70 mm Hg, whereas in the pressure range between 70 and 200 mm Hg it remained essentially unchanged. The findings indicate an autoregulative response in both the cortical and medullary circulation.
A Note on the Influence of Asynchronous Activation on Myocardial Contraction
Authors: Jóhannsson M. , Nilsson E. 
Published: December 2008

AbstractPairs of rabbit papillary muscles were mounted in series to make it possible to study the effects of asynchronous activation on myocardial contraction. The two muscles were connected together via platinum loops hooked to a lever (displacement transducer), the other end of each muscle being fixed to a force transducer. The force of each muscle was measured at various contraction frequencies with the lever fixed (isometric contractions) or freely movable (auxotonic contractions). With auxotonic contractions, asynchronous activation (25 or 50 ms interval between stimulation of the two muscles) increased the movements of the muscles, decreased their force, and prolonged the duration of the contraction at 37°C. These effects were greater, the higher the contraction frequency within the range 30–150 beats/min. On the basis of these results, it is suggested that the physiological asynchrony of the myocardial contraction in vivo tends to offset frequency‐induced changes at the cellular lever (enhanced intensity of active state, shortening of active state duration).
Secretion from the Dog's Parotid at Different Time Intervals after Denervation
Authors: Holmberg Jan 
Published: December 2008

AbstractPrevious observations suggest that cholinergic secretory fibres reach the dog's parotid gland not only via the auriculo‐temporal nerve but also along the internal maxillary artery. 3–5 days after section of both these sets of nerves citric acid applied to the oral mucosa was found to evoke slow secretion only, or none at all. It has been reported, however, that the secretory response elicited reflexly after auriculo‐temporal nerve section gradually increases during the days following the operation. The auriculo‐temporal nerve was divided unilaterally in one group of dogs, and in another group this operation was combined with section of the nerves on the internal maxillary artery. During the following five weeks the dogs were examined repeatedly. Each time the secretory innervation was studied in two ways: by pouring citric acid into the mouth and by injecting esenne through the salivary duct into the gland. In addition the secretory responses to methacholine were estimated. The results indicate that postoperatively there was first a period in which there wag some increased release of acetylcholine in the gland (a “degeneration phenomenon”); supersensitivity then developed in the secretory cells. In spite of these complications both methods to study the secretory innervation could be used after the first week and onwards to demonstrate the difference in the effectiveness between the two denervation procedures.
Studies of Blood‐pressure Regulation IV. The Effects of Impulse Train Stimulation of the Carotid‐sinus Nerves
Authors: Jonzon A. , ÖBerg P. Å. , Sedin G. , Sjöstrand U. 
Published: December 2008

AbstractThe effect of sinus nerve stimulation on the blood pressure and heart rate was studied in dogs. Electrical stimulation of the sinus nerves of both sides was given both in the form of 2 types of intermittent impulse trains and as impulses of constant frequency. The intermittent impulse bursts, which were synchronized with the ECG, comprised 5–50 imp which coincided with systole (150 ms). Comparisons were made between stimulation with a constant frequency and the intermittent types, with the same number of impulses per cardiac cycle. It was found that the maximal blood pressure reduction was already reached at 5–10 imp per cardiac cycle. The difference between stimulation with a constant frequency and the intermittent types, with the same number of impulses per cardiac cycle, is negligible as regards blood pressure reduction but the intermittent type has a greater effect on the heart rate. Sinus nerve stimulation in massive haemorrhage and the influence of the amplitude of the stimulation signal were also studied.
Gastric Absorption of L(+) and D(‐) Lactic Acid and their Effects on the Transmucosal Ion Transport in Innervated, Non‐secreting Cat Stomachs
Authors: Frenning Bertil 
Published: December 2008

AbstractOn instillation of 170 mM lactic acid (L or D) into unstimulated whole stomach pouches in cats the hydrogen ion concentration decreased more slowly than on instillation of 170 mM hydrochloric acid. When 700 mM lactic acid (L or D) was instilled the reverse was found. On instillation of 170 mM HCI subsequent to an instillation of 170 mM lactic acid (L or D) the changes in concentration of eleotrolytes as well as the net fluxes of electrolytes were of the same order of magnitude as during a preceding control instillation of HCI. On instillation of 170 mM HCI subsequent to an instillation of 700 mM lactic acid (L or D) the decrease in hydrogen ion concentration and the increase in sodium ion concentration were significantly larger than in the control instillation of HCI. The net influx of sodium ions was significantly increased but not the net efflux of hydrogen ions. After exposure of the gastric mucosa to 700 mM lactic acid (L or D) it produced a mucoid fluid that contained mainly sodium and chloride ions. This explained the results obtained when HCl was instilled subsequent to an instillation of 700 mM lactic acid. No morphological changes were found on examination in the scanning electron microscope of gastric mucosae exposed to 6 ml of 700 mM L lactic acid.
Centrally Mediated Effects of Sodium and Angiotensin II on Arterial Blood Pressure and Fluid Balance
Authors: Andersson B. , Eriksson L. , Fernández O. , Kolmodin C.‐G. , Oltner R. 
Published: December 2008

AbstractFour kinds of infusions were made for 1 h periods into the 3rd cerebral ventricle of hydrated, conscious goats: 1) Angiotensin in hypertonic NaCI, 2) angiotensin in slightly hypotonic NaCI, 3) angiotensin in isotonic d‐glucose, and 4) hypertonic NaCI. The influence of these infusions on carotid blood pressure and fluid balance was studied. The infusions of angiotensin in hypertonic NaCl had conspicuous hypertensive, dipsogenic, antidiuretic and natriuretic effects. More moderate responses of the same kinds were obtained during the infusions of hypertonic NaCl and of angiotensin in slightly hypotonic NaCI. In contrast, no or only weak effects were obtained by the infusions of angiotensin in isotonic d‐glucose. The results are taken as support for the idea that a Na+sensitive system in the vicinity of the 3rd ventricle may be of importance in the central contml of fluid balance and arterial blood pressure. Such a system may be influenced by the Na+concentration of the cerebrospinal fluid, and angiotensin may either sensitize it to Na+ or make it more exposed to Na+ions.
Vagal and Sympathetic Efferent Discharge in the Bainbridge Reflex of Dogs
Authors: Hakumäki Martti O. K. 
Published: December 2008

AbstractA study has been made of the response in vagal and sympathetic cardiac efferentation to i.v. injection, in Bainbridge type experiments on dogs anesthetized with i.v. chloralose. Cardiac vagal efferent activity was recorded from the cervical vagus, and sympathetic cardiac efferentation from the postganglionic cardiac fibres. An increase in sympathetic cardiac discharge, along with diminution in the vagal cardiac discharge, with associated tachycardia, has been detected in the Bainbridge reflex of dogs. A positive linear correlation was observable between the heart rate and the ratio of sympathetic and vagal number of impulses. The acid‐base balance of the experimental animal was controlled.
In Vitro Work Load and Rat Heart Metabolism: II. Effect on amino acid transport
Authors: Ahrén K. , Hjalmarson Å. , Isaksson O. 
Published: December 2008

Abstract In vitro pressure overload was found to accelerate protein synthesis in the isolated working rat heart (Hjalmarson and Isaksson 1972 a). Since membrane transport of amino acids is considered to be one rate‐limiting step in protein synthesis, the amino acid transport in the isolated rat heart was investigated using the non‐utilizable amino acids α‐aminoisobutyric acid (AIB) and 1‐aminocyclopentane carboxylic acid (cycloleucine). Increased pressure load (afterload) accelerated amino acid uptake after a perfusion period of 15 ruin, and a 50—100% increase in the intracellular to extracellular distribution ratio of the amino acids was seen after 60 min of perfusion. This accelerated uptake was not inhibited by cycloheximide, suggesting that the work load effect was not dependent upon a continuous synthesis of proteins. The accumulation rate continued to be stimulated for some time after normalization of the work load and coronary flow, indicating that the work load effect was not directly linked to coronary flow. Increased preload did not stimulate amino acid uptake. Hearts from hypophysectomized rats showed a decreased concentrative uptake but the amino acid uptake was still accelerated by pressure overload. It is suggested that an increased uptake of amino acids could be of physiological significance in relation to the increased protein synthesis under these conditions.
The Release of Protein in the Course of Catecholamine Secretion from Bovine Adrenals Perfused in Vitro
Authors: Serck‐Hanssen Guldborg 
Published: December 2008

AbstractThe release of protein from chromaffin granules during catecholamine secretion has been studied in bovine adrenals perfusedin vitro. In response to acetylcholine an increased output of catecholamines as well as protein from the glands occurred. Secretion caused a reduction in protein content of chromaffin granules corresponding to the amount of amines released. The quantity of protein released during secretion from the large granule fraction, the fraction containing the chromaffin granules, was of a magnitude compatible with secretion of the total content of water‐soluble protein in the chromaffin granule. These observations are consistent with an all‐or‐none release mechanism for the adreno‐medullary chromaffin granules.
Choline Acetyltransferase in the Normal and Parasympathetically Denervated Parotid Gland of the Dog
Authors: Ekström Jörgen , Holmberg Jan 
Published: December 2008

AbstractThe reduction of the activity of the acetylcholine‐synthetizing enzyme, choline acetyltransferase, has been used as an indicator of the effectiveness of the denervation obtained by various operative procedures in the parotid gland of the dog. After division of the auriculo‐temporal nerve about 30 % of the normal enzyme activity still remained in the gland A reduction of the activity to about 10 % was obtained when both this nerve and the recently described secretory nerves on the internal maxillary artery had been cut. When in addition to these two sets of nerves, the facial nerve was severed as well, the choline acetyltransferase activity was not measurable. Electrical stimulation of the facial nerve was found to provoke a slight secretion from the gland.
Histochemical Studies of Uterine Innervation after Neurectomies
Authors: Kanerva Lasse , Mustonen Tapio , Teräväinen Heikki 
Published: December 2008

AbstractThe distribution of nerves of the uterus containing acetylcholinesterase (AChE) and catecholamine (CA) was studied with light microscopic histochemical techniques after sympathectomy, parasympathectomy, and removal of the paracervical ganglion in the rat. A rich plexus of AChE‐containing nerves was present both in the myometrium and around the uterine blood vessels. Nerve fibres exhibiting CA fluorescence were abundant around the blood vessels, but only sparse in the myometrium. Sympathectomy resulted in the disappearance of CA‐containing perivascular nerve fibres but left intact the extravascular myometrial nerve fibres: those containing CA and those containing AChE. Parasympathectomy caused a slight decrease in the perivascular AChE‐containing fibres. On the other hand it had no effect on the myometrial AChE‐ or CA‐containing nerve fibres. Bilateral destruction of the paracervical ganglion resulted in the complete disappearance of AChE‐ and CA‐containing fibres, both around the blood vessels and in the myometrium.
Enhancement by Indomethacin of Cold‐Induced Hypersecretion of Noradrenaline in the Rat in vivo ‐ by Suppression of PGE Mediated Feed‐back Control?
Authors: Stjärne Lennart 
Published: December 2008

AbstractWhile indomethacin treatment did not alter the urinary excretion of noradrenaline in the rat at room temperature, it consistently and significantly augmented the urinary hyperexcretion of noradrenaline induced by exposure to cold; the excretion of adrenaline remained initially unchanged. The effect of indomethacin increased progressively with time during the experimental period of about one week. The results imply that indomethacin, which is known to be able to block the formation of PGE in vivo as well as in vitro, augments the secretion of nor‐adrenaline from sympathetic nerves during sympathetic hyperactivity. Since the amount of noradrenaline secreted as a result of nerve stimulation is raised when PGE formation is depressed, in isolated tissues in vitro, the present result may imply that the sympathetic hyper‐secretion induced by indomethacin was secondary to suppression of PGE formation.
Extent of Engagement of Various Cardiovascular Effectors to Alterations of Carotid Sinus Pressure
Authors: Kendrick Ed , Oberg Bengt , Wennergren Göran 
Published: December 2008

AbstractReflex adjustments of blood pressure, heart rate, skeletal muscle and renal resistance vessels to changes in intrasinusal pressure were recorded and the respective sinus pressure—reflex response curves plotted. In this way one could evaluate whether the various individual reflex arcs, which together constitute the baroreceptor reflex control of the circulation, display “threshold” response and maximal sensitivities, respectively, at identical sinus pressures.—The curves describing the blood pressure, muscle and renal resistance vessel responses were found to follow identical courses, while the heart rate response curve was displaced to the right of the others. This discrepancy is, however, in all probability a mere consequence of the peculiar neuro‐effector characteristics in the heart. The individual components of the baroreceptor reflex, therefore seem to be recruited simultaneously when the sinus pressure is increased, and there is thus nothing to indicate that afferents from low and high “threshold” baroreceptors, respectively, are preferentially distributed to different neuron pools in the bulbar cardiovascular centres.—A displacement of the response curves to the right was observed whena) non‐pulsating sinus pressures were used instead of pulsating,b) sinus pressures alterations were induced by lowering the pressure from higher levels instead of elevating it,c) arterial PCO2 was increased.
Effect of Adrenaline on Amino Acid Transport in Perfused Rat Heart
Authors: Isaksson O. , Källfelt B. 
Published: December 2008

AbstractEffects of adrenaline on amino acid transport in the isolated perfused rat heart was investigated using the non‐utilizable amino acidsα‐aminoisobutyric acid (AIB) and 1‐aminocyclopentanecarboxylic acid (cycloleucine). Adrenaline, addedin vitro, caused a dose dependent increase in the uptake of AIB and cycloleucine, and a significant stimulation was seen after 15 min of perfusion. The minimal effective concentration was 5 × 10‐8M, and an effect was obtained when hearts were perfused with glucose or palmitate as substrate and when no exogenous substrate was added. Adrenaline increased the uptake in hearts arrested with high [K+] or tetrodotoxin, and the accelerated uptake was not dependent upon the chronotropic effect of adrenaline. Under conditions when adrenaline increased amino acid uptake, protein synthesis was either unaffected or decreased. The data of the present study show that adrenaline directly stimulates amino acid transport in the heart and it is concluded that increased uptake of amino acids could be an energy‐generating system for the heart during adrenergic stimulation.
Steady State Contribution of the Na, K‐Pump to the Membrane Potential in Identified Neurons of a Terrestrial Snail, Helix pomatia
Authors: Christoffersen G. R. J. 
Published: December 2008

AbstractThe presence of an electrogenic Na, K‐pump has been demonstrated in identified neurons of the snail, Helix pomatia by the observation of ouabain sensitive hyperpolarizations following increases of intracellular sodium concentration. A contribution of the pump to the resting membrane potential (RMP) has been measured at varying extracellular potassium concentration as the depolarizing effect of ouabain upon RMP. The contribution was found to have a value of – 7 mV at 4 mM external potassium and to decline with increasing and decreasing K‐concentrations. The electrogenic flux has been calculated by two independent methods from measurements of membrane resistance and the electrogenic contribution to the RMP. Agreement was found when the flux was computed both from modified constant field equations and from Ohm's law. The flux increased from zero at 0 mM external potassium concentration to –10 peq cm–2 s–1 at 6 mM and stayed at this level with rising concentrations of K. It is concluded that the decrease of the electrogenic contribution to RMP observed at low K‐concentrations is caused by inhibition of the electrogenic flux whereas the decline of the contribution seen at higher K‐concentrations is due to a diminution of the membrane resistance (increment of potassium permeability) rather than to a fall of the electrogenic flux.