bluuebunny/crossref_metadata_2025_split huggingface dataset:
3H‐Noradrenaline Release and Mechanical Response in the Field Stimulated Mouse Vas Deferens
Authors: Farnebo Lars‐Ove , Malmfors Torbjörn 
Published: December 2008

AbstractIsolated mouse vas deferens was preincubated with3H‐noradrenaline (3H‐NA) and then mounted in a small glass chamber where it was superfused with buffer and stimulated by an electrical field. Tritium overflow into the buffer and mechanical activity was followed.Almost all the radioactivity taken up and retained in the vas deferens, and about 75 % of the tritium overflow during stimulation was due to3H‐NA. Stimulation for 30 sec at 4–16 Hz caused a biphasic contraction of the vas deferens with an initial rapid twitch and a second tetanus‐like phase of contraction. The stimulation‐induced tritium overflow during stimulation at 16 Hz for 30 sec was 1.8 %(i.e.1.8 % of the total tritium content of the vas deferens was overflowing in response to stimulation). The fraction of the tritium content of the vas deferens overflowingperimpulse at different frequencies of stimulation was the same at 1–16 Hz and was around 3.5 xlO“5. Upon stimulation for various time periods (10–120 sec) the stimulation‐induced overflow was found to be proportional to time. The mechanical response, on the other hand, decreased upon prolonged stimulation.No contractions were elicited in vas deferens from mice pretreated with 6‐OH‐dopamine. Atropine did not affect the response to stimulation. No contraction and no stimulation‐induced overflow was obtained when tetrodotoxin was added to the superfusing buffer. Inhibition of neuronal uptake of NA by desipramine potentiated the contraction caused by stimulation, but the stimulation‐induced overflow was almost unchanged. The a‐receptor blocking drugs phentolamine and phenoxybenzamine decreased the second phase of contraction and increased the stimulation‐induced overflow. Papaverine inhibited the contraction and increased the stimulation‐induced overflow. Stimulation of a‐receptors by methoxamine potentiated the contraction and decreased the stimulation‐induced overflow.From the drug‐experiments it is concluded that a decreased effector response is accompanied by an increased3H‐NA release, while an increased effector response is accompanied by a decreased3H‐NA release. The results indicate the existence of a transsynaptic regulatory mechanism for NA release.
Synthesis of Noradrenaline in Isolated Rat Iris during Field Stimulation
Authors: Farnebo Lars‐Ove , Lidbrink Peter 
Published: December 2008

AbstractIsolated rat irides from untreated rats or rats pretreated with the tyrosine hydroxylase inhibitor H44/68 or the dopamine‐β‐hydroxylase inhibitor FLA63 were incubated in physiologic buffer for 30 min and then superfused by buffer for 60 min in small chambers. Some of the irides were stimulated by an electrical field at 10 Hz for 60 min. Endogenous NA was enzymatically determined or the irides were examined with the fluorescence histochemical method of Falck and Hillarp. Irides that were not stimulated contained about 5 ng noradrenaline (NA) per iris. Stimulation reduced the NA content of irides from untreated or FLA63 pretreated rats to about 60%of the unstimulated control. Stimulation caused an altered distribution of NA with a less pronounced cumulation of NA to the varicosities of the adrenergic nerve terminals. Addition of tyrosine to the superfusing buffer did not diminish the stimulation‐induced decrease of NA. In irides from rats pretreated with H44/68, stimulation reduced the NA content to about 25%of the unstimulated control. A great reduction of the fluorescence intensity of the majority of the nerve terminals was observed. The difference found in stimulation‐induced depletion of endogenous NA between irides of untreated and H44/68 pretreated rats is most likely due to synthesis of NAin vitroin the irides of untreated rats.
Drug‐Induced Changes in the Release of3H‐Monoamines from Field Stimulated Rat Brain Slices
Authors: Farnebo Lars‐Ove , Hamberger Bertil 
Published: December 2008

AbstractRat cerebral cortex slices preincubated with3H‐noradrenaline (NA) or3H‐5‐hydroxy‐tryptamine (5‐HT) and neostriatal slices preincubated with3H‐dopamine (DA) were stimulated by an electrical field and the overflow of radioactivity determined. The effect of drugs on overflow and release from central NA, DA and 5‐HT nerve terminals was studied. Inhibition of monoamine uptake with desipramine, cocaine or chlorimipramine increases the stimulation‐induced overflow and the results indicate that at least 35%of the released monoamines may be taken up again into the monoamine nerve terminals. Activation of NA, DA and 5‐HT receptors with clonidine, apomorphine and LSD‐25 respectively seems to decrease transmitter release. Blockade of NA and DA receptors with neuroleptic drugs increases the stimulation‐induced overflow, probably due to an increased release from the NA and DA nerve terminals. It is known that drugs used in the present investigation have a nerve impulse dependent influence on the rate of synthesis and turnover of monoamines in the central nervous system, which is generally considered to be secondary to changes in nerve impulse frequencyviaanervousfeed‐back mechanism. However, it seems probable from the present results that the turnover changes foundin vivoafter these drugs may at least partly also be due to alocaleffect at the central monoamine synapse, possiblyviaa negative feed‐back mechanism.
Relationships between Force and Velocity of Shortening in Rabbit Papillary Muscle
Authors: Edman K. A. P. , Nilsson E. 
Published: December 2008

AbstractThe instantaneous relationship between isotonic load and velocity of shortening was studied in rabbit papillary muscles using a quick‐release technique which involved critical damping of the lever. The force‐velocity curve was determined from the experimental data by means of the least squares method using a computer program. The curve exhibited a true hyperbolic shape and virtually the same values of the constantsaandbin Hill's equation were obtained when the analysis was carried out during the rising or falling phase of an isometric contraction. The experimental basis of the discrepant results reported in previous studies has been scrutinized. Variability in active state intensity and contractile element length between individual force‐velocity determinations may account for the non‐hyperbolic shape of the force‐velocity curve obtained in an analysis of after loaded contractions. Quick releases performedwithoutcritical damping of the lever movements were found to have a depressant effect upon the myocardial activity resulting in a distortion of the force‐velocity curve at intermediate and small loads. The distortion of the curve was more pronounced when the analysis was carried out during relaxation than during the rising phase of the contraction. The deactivating effect is most likely attributable to the rapid fluctuations in speed of shortening of the contractile unit caused by inertial oscillations of the lever system after an underdamped quick‐release.
Effects of Hypoxia and Glucocorticoids on the Histochemically Demonstrable Catecholamines of the Newborn Rat Carotid Body
Authors: Hervonen Antti , Kanerva Lasse , Korkala Olli , Partanen Seppo 
Published: December 2008

AbstractThe histochemically demonstrable catecholamines of newborn rat carotid bodies were studied using the formaldehyde induced fluorescence (FIF) method. The effects of both heavy anoxia and repeated injections by glucocorticoids were registered. The newborn rat carotid body consisted of bright yellow fluorescing cells. During the following 2 weeks the intensity of this fluorescence decreased distinctly while fluorescent network of adrenergic nerve fibres developed. The fluorescent nerves were in close contact with the chief cells of the carotid body. Hydro‐cortisone or prednisolone treatment prevented the loss of fluorescence normally occurring. Anoxia caused a marked decrease in the FIF in the majority of glomus cells in 9—16 day old rats.
Effect of 6‐Hydroxydopamine on the Ganglion Cells and the Small Intensely Fluorescent Cells in the Superior Cervical Ganglion of the Rat
Authors: Eränkö Liisa , Eränkö Olavi 
Published: December 2008

AbstractNewborn rats were injected daily for 8 days with 6‐hydroxydopamine, (6‐OH‐DA) 50 mg/kg b. w. Disappearance of over 90 % of the ganglion cells from the superior cervical ganglion and the coeliac ganglion was observed 3 weeks after discontinuation of the injections. The surviving ganglion cells were larger than normal and exhibited less intense than normal catecholamine fluorescence but showed normal or slightly decreased activity of acetylcholinesterase and nonspecific cholinesterase. Electron microscopically, hypertrophy of the endoplasmic reticulum and the Golgi apparatus were observed. 6‐OH‐DA caused, besides destruction of ganglion cells, an increase in the relative number of the small intensely fluorescent cells. However, this increase was due to loss of ganglion cells from between the small cells, and the total number of small intensely fluorescent cells counted from complete series of sections through the ganglia was the same in controls as that in animals injected with 6‐OH‐DA. It is concluded that the small intensely fluorescent cells are resistant to chemical sympathectomy, and differ in this respect from ordinary ganglion cells.
Effect of Hydrocortisone on Histochemically Demonstrable Catecholamines in the Sympathetic Ganglia and Extra‐adrenal Chromaffin Tissue of the Rat
Authors: Eränkö Liisa , Eränkö Olavi 
Published: December 2008

AbstractHydrocortisone acetate was administered intraperitoneally to newborn rats daily for 5 days, 40 mg/kg b.w. They were killed on the 6th day. Adult rats were given the same dose daily for 14 days and killed on the 16th day. Catecholamines were demonstrated by formaldehyde vapour induced fluorescence. In the 6‐day‐old rats treated with hydrocortisone there was a distinct increase in the size of the extra‐adrenal chromaffin bodies, in the number of fluorescent cells in them and in the intensity of the fluorescence of these cells, as compared with the controls. Hydrocortisone treatment also caused about a tenfold increase in the number of the small intensely fluorescent (SIF) cells in the superior cervical ganglion, the coeliac ganglion and the lumbar prevertebral ganglia of the young rats. The newly formed SIF cells were scattered single or in clusters of a few cells throughout the ganglia, including sites in which no SIF cells were normally present before hydrocortisone treatment. In the adult rats, hydrocortisone did not cause any dramatic changes in the sympathetic ganglia. The SIF cells were present in clusters in the same way as in the control ganglia but there was a tendency towards an increase in the number of SIF cells in the clusters. It is concluded that hydrocortisone causes in young rats a greatly increased formation of the SIF cells from poorly differentiated, weakly fluorescent stem cells, while proliferation of already existent SIF cells is less pronounced.
General Characteristics of Sympathetic Activity in Human Skin Nerves
Authors: Hagbarth K.‐E. , Hallin R. G. , Hongell A. , Torebjörk H. E. , Wallin B. G. 
Published: December 2008

AbstractSynchronized bursts of efferent sympathetic impulses, appearing either spontaneously or triggered by various peripheral stimuli, were recorded with microelectrodes inserted percutaneously into skin nerve fascicles in alert, adult subjects. The signals were abolished by sympathetic ganglion blocking agents and by Lidocaine nerve blocks proximal to the recording site. Many of the sympathetic discharges were succeeded by skin resistance changes and plethysmographic vasoconstrictor responses within the innervation zone of the fascicle impaled. The sympathetic activity was not pulse synchronous as in muscle nerves and the spontaneous sympathetic volleys occurred largely independently of spontaneous blood pressure variations, indicating a relative lack of baroreflex control of the vasoconstrictor outflow to the skin. A loose coupling was observed, however, between the resting respiratory rhythm and the spontaneous sympathetic bursts in the skin nerves.
Manoeuvres Affecting Sympathetic Outflow in Human Skin Nerves
Authors: Delius W. , Hagbarth K.‐E. , Hongell A. , Wallin B. G. 
Published: December 2008

AbstractSympathetic activity was recorded from human skin nerves during the execution of a variety of different manoeuvres. The neural activity (composed of vasoconstrictor and sudomotor impulses) was regularly affected by emotional, thermal and respiratory stimuli. Mental stress, body cooling and increased respiratory movements all increased the sympathetic outflow, whereas the activity decreased during moderate body warming and when the. subject was calm and relaxed. Manoeuvres known to cause changes in baroreceptor activity usually did not affect the sympathetic outflow to the skin. When comparing neural and effector organ responses during the different manoeuvres the changes in sympathetic activity correlated well with changes in skin vascular resistance (either measured simultaneously or as reported in the literature). A comparison of the sympathetic responses recorded from human skin‐ and muscle nerves was also made. It was concluded that most manoeuvres had different effects in the two nerve types, thereby confirming earlier indirect evidence for selective regional control of the sympathetic outflow.
Reflex Relaxation of the Stomach Elicited from Receptors Located in the Heart. An Analysis of the Receptors and Afferents Involved.
Authors: Abrahamsson Hasse , Thoren Peter 
Published: December 2008

AbstractIn cats anesthetized with chloralose electrical afferent stimulation of the right cardiac nerve promptly elicited marked hypotension, bradycardia and relaxation of the stomach. Stimulation threshold and conduction velocity measurements indicated that the stimulated afferents were unmyelinated fibres. The circulatory and gastric responses were abolished by cervical vagal blockade on the stimulation side. Administration of nicotine intrapericardially or veratrum alkaloids i.v. produced similar circulatory and gastric responses as the electrical nerve stimulation. The effects of veratrum were markedly reduced upon application of a local anesthetic in the pericardial cavity. Reflex gastric relaxation was also elicited in response to occlusion of the ascending aorta or mechanical stimulation of the left ventricle. With occlusion of the pulmonary artery only slight gastric responses were obtained during the occlusion. Pronounced gastric responses were recorded upon occlusion of a coronary artery, the effect being abolished by section of the vagi in the neck. – It is concluded that marked reflex relaxation of the stomach can be elicited from heart receptors, probably located in the left ventricle and with unmyelinated afferents in the vagi. It is suggested that the described reflex gastric response may form part of a vomiting pattern.
Postnatal Development of the Mechanical Response of the Isolated Rat Vas Deferens to Nerve Stimulation
Authors: Swedin Göran 
Published: December 2008

AbstractIsolated vas deferens preparations from rats aged 2–22 days were stimulated transmurally in a superfusion bath. The first responses to postganglionic nerve stimulation appeared in preparations from animals 3 days of age whereas responses to exogenous noradrenaline (NA) and direct stimulation of the smooth muscle cells were obtained one day earlier. Preparations of all ages responded readily to low concentrations of exogenous NA (0.2–5.0, μg/ml) while acetylcholine (ACh) had to be added in much higher concentrations (10–100, μg/ml) to give equal direct responses.a‐receptor blockers (phentolamine or phenoxybenzamine, 0.2–2.0, μg/ml) totally inhibited the contractions of preparations from animals up to about 10 days of age, but thereafter the effect was changed into potentiation of the responses. Atropine (0.5–2.0, μg/ml) generally caused a slight decrease of contractions of preparations up to about 15 days of age, but at later stages it was without effect.It is concluded that the major part of the motor innervation of the rat vas deferens is adrenergic but that subtreshold amounts of ACh probably are liberated from some source within the organ on transmural stimulation. The most probable explanation for the greater sensitivity of the young vas deferens preparations to the specific receptor blockers seem to be a greater accessibility of the junctional receptors, perhaps in combination with relatively smaller amounts of transmitter liberated at these early ages.
Changes in Precapillary Resistance in Skeletal Muscle Vessels Studied by Intravital Microscopy
Authors: Eriksson E. , Lisander B. 
Published: December 2008

AbstractEriksson, E. and B. Lisander.Changes in precapillary resistance in skeletal muscle vessels studied by intravital microscopy.Acta physiol. scand. 1972.84.295– 305.The microcirculation of the cat's tenuissimus muscle was observed with particular regard to internal arterial diameters, linear flow rates and capillary flow distribution. Simultaneous recordings of systemic arterial blood pressure and blood flow in this and adjacent muscles were carried out. The effects of graded vasoconstrictor fibre stimulation or of intra‐arterial vasodilator drug administration could be directly studied in this muscle region. Although causing a slight blood flow increase, acute sympathetic denervation was not followed by any sustained diameter increase in the microvessels studied. Morphologically clearcut precapillary sphincters were not observed and during “rest” the denervated precapillary vessels displayed a fairly steady tone. Nevertheless, capillary flow patterns changed perpetually. Capillary contents were stagnant and flow even reversed sometimes due to transient trapping of passing leucocytes. Maximal drug‐induced dilations caused 50 % diameter increases in arteries of 15–100μ,with smaller changes in larger ones. Intense vasoconstrictor fibre activation lowered flow 6–8 times and reduced diameters in arteries of 15–200μwith a maximum at the 30μsize, where closure could occur. Luminal reductions were absent in immediate precapillary sections. During stimulation a marked leucocytosis was observed in the microvessels. It is concluded that in the muscle studied, lacking morphologicallly distinct precapillary sphincters, variations in capillary blood flow and in the perfused capillary surface area are brought about by luminal changes of end‐arterioles, to which white cell obstruction of microvessels may contribute. Further, the relative importance of the resistance of the different series‐coupled sections may vary considerably with the regional tone. Sections responsible for changes in resistance and in capillary flow distribution are evidently not distinctly separated morphologically.
The Oxygen Supply to the Retina, II. Effects of High Intraocular Pressure and of Increased Arterial Carbon Dioxide Tension on Uveal and Retinal Blood Flow in Cats
Authors: Alm Albert , Bill Anders 
Published: December 2008

AbstractAlm, A. and A. Bill.The oxygen supply to the retina, II. Effects of high intraocular pressure and of increased arterial carbon dioxide tension on uveal and retinal blood flow in cats. A study with radioactively labelled microspheres including flow determinations in brain and some other tissues.Acta physiol. scand. 1972.84.306–319.15μand 35μmicrospheres labelled with8SSr and169Yb were used to determine the rate of blood flow through various intraocular tissues, optic nerve, brain, kidney cortex and small intestine in cats at normal and increased Paco2‐ One eye had its spontaneous intraocular pressure, the other eye had its pressure stabilized at a higher level. At normal Paco2 a reduction in perfusion pressure resulted in decreased vascular resistance in the iris, the ciliary body and the retina, but not in the choroid. In the retina the eye with reduced perfusion pressure had a significantly higher blood flow than the control eye. Increased PaCO2resulted in increased blood flow in all ocular tissues and all extraocular tissues studied except the kidney cortex. Reductions in perfusion pressure at high Paco2resulted in further decreases in vascular resistance in two eyes of seven only.The results suggest that about 21 % of the O2consumed by the retina is delivered by the retinal blood vessels, the rest by the choroid. Both myogenic and metabolic mechanisms seem to contribute to the adjustment of retinal vascular resistance after a change in perfusion pressure.
The Effect of Slight Hypothermia on Liver Function as Measured by the Elimination Rate of Ethanol, the Hepatic Uptake and Excretion of Indocyanine Green and Bile Formation
Authors: Krarup Niels , AnkerLarsen Jens 
Published: December 2008

AbstractKrarup, N. and J. A. Larsen.The effect of slight hypothermia on liver function as measured by the elimination rate of ethanol, the hepatic uptake and excretion of Indocyanine Green and bile formation.Acta physiol. scand. 1972.84.396–407.Liver function was followed by determination of the elimination rate of ethanol, bile flow, the hepatic uptake and excretion of Indocyanine Green and the excretion of bile acids and electrolytes. A fall in the body temperature 1–2oC from normal, was accompanied by a sudden decrease in the elimination rate of ethanol, bile flow and the hepatic uptake and excretion of Indocyanine Green of about 25 per cent. The effect of cooling on bile flow and the elimination rate of ethanol were significantly correlated. The cooling caused only minor effects on the excretion of bile acids and the biliary electrolyte composition. The findings may be explained by intrahepatic vascular changes resulting in a decrease in the number of perfused sinusoids and a corresponding reduction in the functional capacity.
Effect of Increased Afterload on the Inotropic State and Uptake of Free Fatty Acids in the Intact Dog Heart
Authors: Kjekshus J. , Mjøs O. D. 
Published: December 2008

AbstractKjekshus, J. and O. D. Mjøs.Effect of increased afterload on the inotropic state and uptake of free fatty acids in the intact dog heart.Acta physiol. scand. 1972.84.415–427.In anesthetized dogs treated with atropine and pentolinium tartrate–a ganglionic blocking agent–the possibility was tested that release of myocardial catecholamines contributes to the regulation of cardiac output during increased outflow resistance. When left ventricular systolic pressure was raised by an average of 100 mm Hg (from 99 to 193 mm Hg), cardiac output increased (+34 %) from 122 to 163 ml/min kg and maximum rate of rise of left ventricular pressure (dP/dt) (+ 50%) from 1.30 to 1.80 mm Hg 10‐3/s. Myocardial uptake of free fatty acids (FFA) showed an average increase of 221%(from 2.9 to 9.3 μEq/min 100 g), in spite of unchanged arterial FFA concentrations, indicating adrenergic activation of the heart. These responses were abolished following a similar rise in left ventricular systolic pressure (from 88 to 184 mm Hg) in reserpine‐treated dogs during ganglionic blockade. Changes in left ventricular end‐diastolic pressure, as well as myocardial oxygen consumption, were similar in both groups. The present study supports the conclusion that catecholamines are released from myocardial stores during augmented intraventricular pressure, thereby explaining the increase in cardiac output. However, in the catecholamine‐depleted heart, cardiac output is maintained by the Frank‐Starling mechanism alone.