bluuebunny/crossref_metadata_2025 huggingface dataset:
Metabolic and hormonal adjustments during hemorrhage in cats after interference with the sympatho‐adrenal system
Authors: ANDERSSON P.‐O. , FARNEBO L.‐O. , FREDHOLM B. B. , HAMBERGER B. , HOLST J. , JÄRHULT J.
Published: December 2008

The relative contribution of the splanchnic sympathetic innervation and the adrenal medulla for metabolism and hormone secretion during two different levels of hemorrhagic hypotension was investigated in 3 groups of anesthetized cats, viz. intact, adrenalectomized and splanchnicotomized (adrenalectomy + cutting of splanchnic nerves). In intact cats, hemorrhage caused very marked elevations of arterial plasma glucose, adrenaline, noradrenaline, dopamine, lactate, CAMP, glycerol and glucagon concentrations whereas plasma insulin fell to only 20% of control values. Adrenalectomy attenuated the glucose, adrenaline, noradrenaline and cAMP responses whereas the normal insulin inhibition was abolished. Splanchnicotomy further reduced the hemorrhagic glucose and glycerol responses and, possibly, also that of glucagon. It is concluded that the adrenergic system as a whole is important for the adjustments of the release of glucose, CAMP, glycerol, insulin and glucagon that occur during hemorrhage in cats. The adrenal medulla seems to be of particular importance for the regulation of cAMP release.
Effect of spinal sympathetic blockade upon postural changes of blood flow in human peripheral tissues
Authors: SKAGEN KNUD , HAXHOLDT OLGA , HENRIKSEN OLE , DYRBERG VIGGO
Published: December 2008

The effect of head‐up tilt upon subcutaneous and skeletal muscle blood flow in the crus was studied before and during epidural blockade in 10 subjects. Relative changes in blood flow were estimated by the local 133Xe washout technique. In subcutaneous tissue head‐up tilt induced a decrease in blood flow of about 40% and there was no difference in the vascular response to head‐up tilt before and during epidural blockade. In skeletal muscle tissue essentially the same was found as head‐up tilt decreased blood flow by about 26% the response being uninfluenced by epidural blockade. In 3 patients local nervous blockade was induced by Lidocaine in 133Xe labelled subcutaneous tissue on one side. During epidural blockade and tilt blood flow increased by 12% whereas blood flow decreased by 30% on the control side. Thus epidural blockade had no influence on the vasoconstrictor response in subcutaneous tissue and skeletal muscle to head‐up tilt whereas local blockade was able to prevent the response. Local mechanisms including the local veno‐arteriolar reflex appear to play an important role for the observed maintenance of arterial blood pressure in the tilted position during central sympathetic blockade.
The dependence of the latency relaxation on temperature in single muscle fibres of the frog
Authors: HAUGEN P.
Published: December 2008

The time course of the latency relaxation was studied at various temperatures in the range 0–26°C. Over the entire range the time of onset of the drop in tension, t1, was independent of sarcomere length. At temperatures above 12–15°C the falling phase had a point of inflexion, while at lower temperatures there was an interval during which the tension fell at a constante rate. The time when the rate of drop in tension had passed its maximum value t1,2, the time to the maximurn drop in tension t2, and the time when the tension crossed the resting level t3, all showed linear dependence on sarcomere length in the range from 2.1 to 2.7–3.4 μm. In this range the durations of the intervals t1.2‐t1, t2‐t1, and t3‐t1 were nearly proportional to the distance from the Z‐line to the end of the zone of overlap between the thick and the thin filaments. This could be explained as the activation being a longitudinal process starting from the Z‐line. The slopes (dt/dS) of the linear portions of the time variables t1,2, t2, and t3 in a time‐sarcomere length (S) diagram all had the same dependence on temperature giving a Q10 of 1.75. Under the assumption that the activation process followed a diffusion of calcium from the Z‐line region to the zone of overlap a diffusion coefficient was estimated. At room temperature it had a magnitude of about 1/20 of that for calcium chloride in water. It had a dependence on temperature corresponding to an Arrhenius activation energy of about 37 kJ/mol which is about twice the activation energy for a simple diffusion of calcium in water. The results can be interpreted in terms of the time course of the latency relaxation mainly reflecting a longitudinal diffusion of calcium ions in the sarcoplasm.
Effects of halothane‐nitrous oxide inhalation anesthesia and lnactin on overall renal and tubular function in Sprague‐Dawley and Wistar rats
Authors: HOLSTEIN‐RATHLOU N.‐H. , CHRISTENSEN P. , LEYSSAC P. P.
Published: December 2008

Renal function, plasma renin concentration (PRC) and prostaglandin (PG) excretion rate was studied in groups of Sprdgue‐Dawley (SPRD) and Wistar (WIST) rats anesthetized with either Halothane‐N2O or Inactin. Conscious rats were used as controls. A. In Halothane‐N2O anesthesia inulin clearance (CIN) and absolute proximal reabsorption rate (APR) was moderately decreased (by about 20%). while renal plasma flow (RPF), urine flow and solute excretion remained unchanged as compared to conscious rats. There was a linear relationship between the reciprocal of the proximal occlusion time (OT) and CINin Halothane anesthesia indicating that the proximal luminal diameter was constant and independent of CIN. B. In Inactin anesthesia CINwas similarly reduced but APR was more depressed (by about 35%). RPF and solute excretion rate decreased only in SPRD rats, while urine flow was significantly reduced in both strains. l/OT was invariant to changes in CINindicating luminal diameter variations in proportion to CIN. Urinary PGE2‐and PGF2αexcretion rates and PRC were moderately elevated in operated animals of both strains regardless of the anesthetics used. It is concluded that renal functional parameters in surgically prepared rats are more severely depressed by Inactin than by Halothane‐N2O anesthesia. The gas anesthesia is equally well tolerated by both strains of rats.
Suppression of postganglionic sympathetic discharges by pentobarbital in endotoxic cats
Authors: HALINEN M. O. , HAKUMÄKI M. O. K. , SARAJAS H. S. S.
Published: December 2008

Pentobarbital (7–9 mg/kg) profoundly suppressed the sympathetic postganglionic cardiac and splenic discharges in endotoxic cats under chloralose anesthesia. Concurrently, the pre‐existent tachycardia was replaced by bradycardia, and the blood pressure fell further. The findings are interpreted to imply a pentobarbital‐induced syrnpatolysis.
Left ventricular hypertrophy improves cardiac performance in spontaneously hypertensive rats
Authors: LUNDIN S. , FRIBERG P. , HALLBÄCK‐NORDLANDER M.
Published: December 2008

Cardiac function was studied in spontaneously breathing, adult spontaneously hypertensive rats (SHR) and Wistar‐Kyoto normotensive rats (WKY). By rapid intravenous blood infusion, the relation between left ventricular end‐diastolic pressure (LVEDP) and stroke volume (SV) was determined while the cardiac nervous control was pharmacologically blocked. Since SV is greatly influenced by the level of afterload (mean arterial pressure, MAP), SV was also determined at increased MAP (constriction of abdominal aorta) and at decreased MAP (vasodilation by hydralazine). At low LVEDP levels, a righward shift of the Frank‐Starling relationship was observed in SHR. This rightward shift seems mainly to depend on the increased MAP present in SHR since it was less prominent if MAP was lowered to normotensive levels in SHR. Maximal SV during volume infusion was similar in SHR and WKY, despite a much higher MAP in SHR. When peak SV was instead compared at similar MAP levels for both (either at ‘normotensive’ or ‘hypertensive’ levels) it was always significantly greater in SHR, and was increased largely in proportion to their increased left ventricular weight. This indicates that the left ventricular hypertrophy present in SHR is, at least at this stage, a physiological adaptation of the heart to increase its performance, in order to maintain a normal SV and hence cardiac output, despite an increased arterial pressure.
Effect of denervation on acetylcholine synthesizing activity and nicotine‐like binding sites in rat hind limb muscles
Authors: AQUILONIUS STEN‐MAGNUS , ASKMARK HÅKAN , ECKERNÄS SVEN‐ÅKE , NORDBERG AGNETA
Published: December 2008

The acetylcholine synthesizing (ACh‐s) activity and the binding of the nicotinic ligands 3H‐α‐bungarotoxin (α‐Btx) and 3H‐d‐tubocurarine (d‐TC) were analysed in rat hind limb muscles 1–32 days after denervation. Muscles of the contralateral leg served as controls. ACh‐s activity was considerably lower in tibialis anterior as compared to the extensor digitorum longus and the peroneus longus muscles. After denervation there was a rapid decrease in ACh‐s activity in parallel to a considerable increase in α‐Btx binding. The binding of d‐TC was essentially unchanged following denervation indicating the special characteristics of the newly formed receptors. ACh‐s activity can be differentiated into one specific (choline acetyltransferase) and one unspecific component.
Impairment during marked hypotension of the plasma volume control in hemorrhage
Authors: LUNDVALL JAN , GUSTAFSSON DAVID
Published: December 2008

During hypovolemia extravascular fluid is transferred across the capillaries into the circulation in order to restore blood volume. Several studies have shown that this process. which mainly occurs in skeletal muscle, effectively can compensate for the blood loss. The present investigation performed in the cat strongly indicates, however. that this vital compensatory mechanism is inactivated in situations of pronounced hypovolemia leading to hypotension levels of 30–40 mmHg, i.e. when the need for refill of the circulatory system is most in demand. It is suggested that the cessation of fluid transfer from skeletal muscle to blood during marked hypotension is causally linked to the evoked pronounced reduction of blood flow, due partly to the much reduced perfusion pressure and partly to the marked vasoconstriction. Pronounced vasoconstriction in the hemodynamically important vascular bed of skeletal muscle is obviously an essential part of the necessary resistance response evoked in the systemic circulation in order to avoid circulatory collapse already in the early phase of a large blood loss. However, the chances for the organism to survive is minimized if the vasoconstriction leads to impairment of the mechanisms for plasma volume regulation.
Quantitative measurements of the alcohol concentration and the temperature of breath during a prolonged exhalation
Authors: JONES A. W.
Published: December 2008

After healthy men drank a moderate dose of alcohol their breath‐alcohol concentrations and breath‐temperatures were quantitatively determined as a function of expired‐volume. All test were made in the post‐absorptive phase of ethanol metabolism and breath samples were analysed by gas‐liquid chromatography. The temperatures of breath rose steadily from start to end of exhalation with a mean of 34.48°C after a forced vital capacity (FVC) maneuver. The standard deviation of a single measurement of breath‐temperature in randomly selected subjects was ±0.402°C. No statistically significant increases in the temperature of breath were noted after an expired volume of 70% FVC. At average expired‐breath volumes of 13.5%. 26.2%. 52.2%. 71.7% and 94.2% FVC the breath‐temperatures were 33.3°C. 33.5°C. 33.9°C. 34.1°C and 34.4°C whereas breath‐alcohol concentration were 79.7%. 85.9%. 90.5%. 95.9% and 98.8% of the 100% FVC alcohol levels. When I corrected for the lower temperatures of breath in the early stages of expiration, the concentrations of alcohol were 86.6%. 90.8%. 93.5%. 96.5% and 98.5% of the 100% FVC levels. These results show that at least 70% of a man's vital capacity must be discarded before a breath‐concentration plateau for ethanol develops. But even after a discard breath‐volume of 10% FVC the concentration of alcohol reaches 80% of the level in end‐expiratory breath. I suspect that ethanol dissolves in the mucous‐membranes of the upper respiratory tract and equilibrates with breath in the airway dead‐space and in the mouth.
Exchange of isethionate between blood and tissues in adult and 7‐day‐old mice
Authors: KUMPULAINEN E. , PESONEN I. , LÄHDESMÄKI P.
Published: December 2008

[14C] lsethionate was injected intramuscularly into adult and 7‐day‐old mice and the distribution of the label in the blood, brain, heart, liver and spleen was determined. Endogenous isethionate in these tissues was determined and approximate exchange rates calculated from the endogenous isethionate tissue levels and specific radioactivities after certain time intervals. The concentration of isethionate was higher and its exchange rates between plasma and tissues faster in the adult mice than in the 7‐day‐old mice. A close correlation between isethionate transport rates and tissue levels in vivo was obtained in both age groups. The tissues eliminated isethionate rapidly, even faster in the adult than in the 7‐day‐old mice. The elimination of isethionate showed three different components, fast, intermediate and slow, in the heart, liver and spleen of the adult mice. but only two components. Fdst and slow, in the other cases.
Uptake and energy‐dependent extrusion of calcium in the rat uterus
Authors: BATRA SATISH
Published: December 2008

BATRA, S.: Uptake and energy‐dependent extrusion of calcium in the rat uterus. Acta Physiol Scand 1982, 114: 447–452. Received 24 Aug. 1981. ISSN 0001–6772. Department of Obstetrics and Gynecology. University of Lund and Leo Research Laboratories, Helsingborg, Sweden.

The ability of lanthanum (La) to displace extracellular calcium or/and block calcium efflux from smooth muscle cells of the rat uterus was examined. Presence of 10 mM La in the medium used for tissue wash following45Ta uptake (La method) increased45Ca efflux particularly in the early phase (60 min) indicating displacement of extracellular calcium. Lowering of temperature from 37°C to 2°C of the La wash resulted in about three‐fold increase in45Ca retention by the tissue. Depolarization of tissue induced by high KCI during La wash at 37°C had no effect on the retention of45Ca. However, depolarization during45Ca uptake significantly increased45Ca uptake by the tissue which was counteracted by the presence of Nifedipine in the medium. The inhibition of tissue metabolic activity by FCCP had different effects on45Ca retention depending on whether the tissues were washed at 37°C or TC. When active45Ca extrusion during tissue washing was blocked (2°C).45Ca content of the tissues exposed to FCCP was reduced by about 35%. When tissues were allowed to actively pump out45Ca (37°C).45Ca content of FCCP exposed tissues was increased by about 50%. It is concluded that about two thirds of the Ca extruded by the tissue is resistant to La blockage, and is dependent on the energy provided by tissue metabolic activity. During the use of the standard La method for measuring cellular calcium in the uterus, there is an underestimation due to unblocked45Ca loss.
Inhibition of gastric acid secretion in the Atlantic cod, Gadus morhua, by sulphated and desulphated gastrin, caerulein, and CCK‐octapeptide
Authors: HOLSTEIN B.
Published: December 2008

Gastric acid secretory effects of gastrin/CCK‐like peptides have been assayed in cods rendered “spontaneously” secreting by a continuous intestinal perfusion with diluted (33%) seawater. A high dose of pentagastrin induced a weak stimulation (31 %) of acid output, while gastrin 17–11, caerulein and CCK8 were inhibitory. Caerulein was the most potent peptide, with an estimated D50for inhibition of 0.013 nmol/kg h. Although displaying lower potencies, also the desulphated forms of gastrin‐17, caerulein and CCK8 were inhibitory. The results may be explained by release of an endogenous inhibitor, or by interaction with endogenous “codfish gastrin”. In the latter case two alternatives are considered: Either gastrin 17. CCK8, and caerulein possess lower efficacies than “codfish gastrin” and therefore act as partial agonists. Alternatively, “codfish gastrin” is itself an inhibitory principle (gastrin). the effect of which is mimicked by gastrin 17. caerulein and CCK8. The actions of gastrin and the gastrin‐like peptides in the cod indicate a structure‐activity relationship different from previously described systems, bot mammalian and submam‐malian.
Effect of vein pump activation upon muscle blood flow and venous pressure in the human leg
Authors: NIELSEN HENRIK VAGN
Published: December 2008

The effect of vein pump activation upon superficial venous pressure and blood flow in human skeletal muscle tissue was studied in 7 healthy subjects. Blood flow was measured in the anterior tibia muscle by the local133Xe washout technique. The subjects were placed on a steeply tilted couch in nearly erect position. The vein pump in gastroenemius‐soleus muscles was activated by heel‐raisings. and the anterior tibial muscle remained relaxed during this procedure. Blood flow in the resting anterior tibial muscle was constant before, during and after 20 heel‐raisings per min. A more heavy exercise with 40 heel‐raisings per min increased blood flow about 100%. This increase in blood flow was absent during venous stasis (40 mmHg), and in areas infiltrated with lidocaine. It is concluded, that intense dynamic exercise in gastrocnemius‐soleus muscles, in erect humans, increased blood flow considerably in another crural muscle remaining in the resting state. The present study strongly suggests, that the observed increase in blood flow, was associated with a decrease in regional subfascial venous pressure to below the threshold level of the local sympathetic veno‐arteriolar reflex.
Performance of the hypertrophied left ventricle in spontaneously hypertensive rats. Effects of adrenergic stimulation
Authors: NORESSON EDDY , THORÉN PETER , HALLBÄCK‐NORDLANDER MARGARETA
Published: December 2008

NORESSON, E., THORÉN, P. & HALLBÄCK‐NORLANDER, M.: Performance of the hypertrophied left ventricle in spontaneously hypertensive rats. Effects of adrenergic stimulation. Acta Physiol Scand 1982, 114:497–504. Received 22 May 1981. ISSN 0001–6772. Department of Physiology. University of Goteborg. Sweden.

The performance of isolated hearts from adult male spontaneously hypertensive rats (SHR) and matched normotensive controls (NCR) was investigated in an antegrade perfusion system, where preload and afterload could be varied independently. During electrical pacing of the heart to constant heart rate. increases in afterload, but not in preload, considerably raised cardiac contractility, measured as left ventricular max dP/dt. At after‐loads equalling their respective in vivo ones. max dP/dt was similar in SHR and NCR. This indicates that the SHR hearts by myocardial hypertrophy are so well adapted to their raised afterload that an increased inotropic state of the heart is not required. Upon adrenaline addition, SHR and NCR did not differ concerning either “chronotropic sensitivity”, i.e. per cent increase in heart rate of the spontaneously beating heart or in “inotropic sensitivity”, measured as increase in max dP/dt. However, in this in vitro situation adrenaline increased stroke volume only when the hearts worked at reduced inotropism, induced by lowered temperature (30°C). At maximal inotropic stimulation by adrenaline and occluded outflow, the SHR hearts produced higher systolic pressures than the NCR ones. This reveals an increased maximal contractile capacity of the hypertrophied SHR left ventricle, rather than a reduced one as sometimes suggested.
Contractile properties of two varieties of twitch muscle fibres in Xenopus laevis
Authors: LÄNNERGREN J. , LINDBLOM P. , JOHANSSON B.
Published: December 2008

The contractile properties of twitch muscle fibres in the iliofibularis muscle of Xenopus laevis with characteristic differences in light‐microscopical appearance have been studied under isometric and isotonic conditions. Type 1 fibres (large. pale) have a short contraction time (te), a shoulder in the relaxation phase, and a high twitch‐tetanus ratio. In type 2 fibres (medium‐to‐large with abundant mitochondria and lipid droplets) te is longer, half‐relaxation time equals te, and the twitch‐tetanus is lower. The capillary density is about 4 times higher for type 2 than for type 1. Computer‐fitted hyperbolic force‐velocity curves gave the following Hill constants (20°C) for type 1 (2) fibres: Po*/Po 1.03 (l.15), a/Po* 0.48 (0.26), b 3.51 (133) Io/s; extrapolated Vmax (0–0.8Po) was 7.60 (6.27) Io/s. Lowered temperature (10°C) increases the curvature of the P‐V relation in type 1 fibres, little effect was seen in type 2. Increased Pco2 depressed the isometric tension in both types; in type I fibres the P‐V relation became less curved, in type 2 fibres no change in curvature was observed. The results suggest that type 1 and type 2 fibres might contain myosin isozymes with slightly different temperature‐ and pH‐sensitivities.
Neuromuscular function and mechanical efficiency of human leg extensor muscles during jumping exercises
Authors: BOSCO C. , ITO A. , KOMI P. V. , LUHTANEN P. , RAHKILA P. , RUSKO H. , VIITASALO J. T.
Published: December 2008

The influence of prestretch amplitude on the mechanical efficiency was examined with 5 subjects, who performed 5 different series of vertical jumps, each of which differed with respect to the mechanics of the knee joint action during the prestretch (eccentric) phase of the contact on the floor. Electromyographic activity was recorded from the major extensor muscles during the entire work period of 1 min per series. In addition, expired air was collected during the test and recovery for determination of energy expenditure. Mechanical work was calculated from the vertical displacement of the body during the jumps. The results indicated that high net efficiency of 38.7% was observed in condition where amplitude of knee bending in eccentric phase was small. In large range motion the corresponding net efficiency was 30.1%. In jumps where no prestretching of extensor muscles ocurred the net efficiency was 19.7%. The high efficiency of small amplitude jumps was characterized by low myoelectrical activity of the leg extensor muscles during the positive (concentric) work phase. In addition, the small amplitude jumps had shorter transition time in the stretch‐shortening cycle, high average eccentric force and high stretching speed. Therefore the results suggest that the restitution of elastic energy, which was also related to the length change and stiffness of the muscles during stretch, plays an important role in regulating the mechanical efficiency of work.
The effect of nicotinic and muscarinic receptor blockade on cholera toxin induced intestinal secretion in rats and cats
Authors: CASSUTO JEAN , JODAL MATS , LUNDGREN OVE
Published: December 2008

The effects of hexamethonium (cholinergic nicotinic receptor antagonist) and atropine (cholinergic muscarinic receptor antagonist) on cholera toxin induced secretion were investigated in denervated segments of the small intestine of rats and cats. While there was no effect of atropine, hexamethonium markedly inhibited choleraic secretion and turned it into a net fluid absorption in many animals. This observation further strengthens our hypothesis that the enteric nervous system is involved in cholera secretion.
Commentary on the reduced urinary noradrenaline excretion following cold stress and exercise in physically trained rats
Authors: APPELGREN BJÖRN , ERIKSSON STEFAN , SJÖSTRAND NILS O.
Published: December 2008

Urinary catecholamine excretions of rats trained by swimming or running were compared with those of cold‐acclimated rats and controls i.e. sedentary warm‐acclimated rats. During cold stress the trained rats excreted less noradrenaline (NA) than did controls. In fact rats trained by swimming excreted less NA than did cold‐acclimated rats. while rats trained by running excreted about the same amount as did cold‐acclimated rats. 2 h of swimming increased the urinary catecholamine (CA) exretions of all groups but trained rats excreted less NA than did controls and cold‐acclimated rats. which had excretions of similar magnitude. The NA excretions of the two trained groups never deviated statistically from each other. It is concluded that concerning NA requirement in order to maintain homeostasis, training produces “cross tolerance” to cold stress but cold‐acclimation does not produce “cross tolerance” to acute exercise. Furthermore the positive effect of training on NA excretion during the stress of cold or that of acute exercise seems essentially to be an effect of increased locomotor activity as such regardless of the type of training. It is also suggested that increased levels of locomotor activity of the rat may be of importance for seasonal acclimation of the species by increasing its tolerance to cold.
Postischemic renal failure. Intrarenal blood flow and functional characteristics in the recovery phase
Authors: KARLBERG LARS , KÄLLSKOG ÖRJAN , NORLÉN BO JOHAN , WOLGAST MATS
Published: December 2008

Intrarenal blood flow, nephron function and whole kidney function were studied in the recovery phase of acute renal failure induced by 45 min of warm ischemia. Analyses were made 24 h, 7 days and 28 days after the ischemic insult. At 24 h the total renal blood flow was 4.0 ml min‐1 g‐1, decreasing to 1.2 within one week. After four weeks it was normalized to 3.4 ml ˙ min‐1˙ g‐1. The intrarenal blood flow distribution, studied with the 86‐Rb extraction method, showed the same pattern of response, with no signs of a persistent heavy reduction in the deeper parts, as was found 10 min after recirculation (Karlberg et al. 1982a). The contralateral, nonischemic kidney responded with hyperemia in all areas 24 h after the trauma, but after 7 days the values were normal. The function of the superficial nephrons was studied with the micropuncture technique. In the initial phase mainly obstructed nephrons were found, but after four weeks the nephrons were essentially normal. After 24 h the postischemic kidneys were anuric but at 7 days urine production had started and the GFR was 0.1 ml min‐1; this improved to 0.55 ml min‐1 after 4 weeks.
Effect of diet on the utilization of blood‐borne and intramuscular substrates during exercise in man
Authors: JANSSON EVA , KAIJSER LENNART
Published: December 2008

20 subjects were studied at rest and during a 25 min submaximal exercise (65% of VO2 max) on two occasions, the first preceded by a fat rich diet and the second by a carbohydrate rich diet. Oxygen uptake, respiratory exchange ratio (R) and arterial‐femoral venous differences for glucose, lactate, β‐hydroxybutyrate and FFA (based on the fractional extraction of 3H‐palmitate) were measured at rest and during exercise. Changes in intramuscular glycogen, triglyceride and lactate concentrations were determined in muscle biopsies taken before and immediately after exercise form m. quadriceps femoris. R was lower after the fat than after the carbohydrate diet and simultaneously the FFA extraction by the exercising leg was higher. The muscle triglycerides did not changes significantly during exercise after either diet. The glucose extraction was insignificantly greater after the fat diet. The glycogen reduction was numerically smaller after the fat diet, but the difference was uncertain and difficult to evaluate due to a large variation after the carbohydrate diet. However, muscle lactate accumulation and release by the exercising leg was smaller after the fat diet, indicating a slower rate of muscle glycogenosis. It is concluded that a fat rich diet increases the relative contribution of fat to the oxidative metabolism, that this increase, to a great extent, is covered by plasma FFA and that the concomitant decrease in carbohydrate utilization concerns muscle glycogen rather than blood glucose.
Myotonia in the rat diaphragm preparation caused by the sulfhydryl inhibiting para‐substituted mercuribenzoates
Authors: RÖED ASBJÖRN
Published: December 2008

The sulfhydryl (SH) inhibiting para‐substituted mercuribenzoates like pOHMB caused a myotonia which appeared as a smooth myotonic profile during recording of the response to twitch stimulation (0.1/s) of isolated rat diaphragm preparations. The maximum myotonic tension varied from about 10% to 200% of the twitch tension at pOHMB addition, and the myotonic repetitive action potential activity varied from a few to more than one hundred action potentials in different cells of the same preparation. The myotonia did not appear after pretreatment with the SH‐reducing agent dithiothreitol, and both dithiothreitol and N‐ethyl‐maleimide inhibited the myotonia. The myotonia increased with temperature, appearing at about 32°C. Increased twitch frequency and tetanic stimulation decreased the myotonia. No change of threshold was observed in myotonic preparations. The myotonia was depressed in K+ ‐free solution, and it was blocked by K+ concentrations exceeding 1.5× normal. The myotonia was reduced when the NaCl was replaced by sucrose or choline chloride. In Ca2+‐free solution the time to maximal myotonic tension and the variability of the maximal myotonia were reduced. Ca2+ concentrations above normal inhibited the myotonia. No myotonia was observed in the slow twitch soleus muscle. pOHMB also caused a twitch depression during indirect and direct stimulation. The depression was observed in soleus muscle and in the diaphragm below 30°C. The depression was thus independent of the myotonia.
A serial study of fluid balance during pregnancy, lactation and anestrus in goats
Authors: OLSSON K. , BENLAMLIH S. , DAHLBORN K. , ÖRBERG J.
Published: December 2008

Water and salt balance was studied in the same goats during pregnancy, lactation and anestrus. All goats increased their water intake during the course of pregnancy, but individual differences were large. In general, twin pregnant (TP) goats drank more water than single pregnant (SP) animals (3.4±0.4; N=11 as compared to 2.5±0.3 litres/day; N=5) during the last weeks of pregnancy. During lactation the high water intake of TP goats persisted and the SP animals increased their intake to the same level as the TP goats. The water intake was reduced to about 2 1/day in both categories of animals during anestrus. Urine volume largely followed the changes in water intake in the individual animal. A continuous decrease in urine osmolality during the course of pregnancy occurred, but during lactation urine osmolality increased towards anestrus levels. TP goats generally retained more sodium than SP animals during pregnancy and during anestrus, whereas the figures were similar during lactation. Plasma Na, K and osmolality remained unchanged during pregnancy, lactation and anestrus, but a large fall in total plasma proteins and a moderate fall in hematocrit were observed during the course of pregnancy. Glomerular filtration rate of TP goats was elevated by about 35% during the 4th month of pregnancy, but did not differ from anestrus levels during the 3rd and 5th month or during lactation. Effective renal plasma flow was highest during the 3rd pregnancy month and then fell to reach lactation and anestrus levels during the 4th month of pregnancy. A few hours before parturition the animals became markedly dehydrated as shown by sudden increases in plasma Na, K, osmolality, total proteins and hematocrit. This water deficit was replenished within 26 h post‐partum.
Temperature responses of rats to treadmill exercise, and the effect of thermoregulatory capacity
Authors: HARRI M. , KUUSELA P. , OKSANEN‐ROSSI R.
Published: December 2008

The relationship between work intensity and body temperature was investigated in the rat in an attempt to clarify whether alterations in thermoregulatory capacity can modify the rate and extent of body warming during exercise. Repeated noradrenaline injections led to increased hyperthermic response to that amine. However, during exercise these animals did not attain higher colonic temperatures as did the animals avoiding noradrenaline treatment. If noradrenaline was injected 60 min prior to test‐exercise the body temperature of the rats rose to a higher level than without the drug. The extent of this rise was, however, independent of the previous noradrenaline‐treatment history. Beta blockade abolished the noradrenaline‐induced hyperthermia but not the exercise‐induced hyperthermia. Despite increased capacity for heat production, cold‐acclimated rats did not attain higher colonic temperatures during exercise than did the running‐trained, cold‐stressed or sedentary control rats. However, the higher tail skin temperature of the cold‐acclimated rats indicate that their heat production was enhanced but they maintained lower colonic temperature by dissipating the excess heat through the elevated blood flow to the tail and probably to other extremities. These results indicate that the rise in deep body temperature of the rats during work is proportional to work intensity and that the enhanced heat production capacity can be compensated for by increasing the heat loss activities.
Decrease of plasma somatostatin‐like immunoreactivity and increase of gastrin and insulin levels in peripheral venous blood of conscious dogs following infusions of pentagastrin. The possible role of vagal “gastrinergic” fibres as inhibitors of gastrointestinal somatostatin release
Authors: UVNÄS‐MOBERG KERSTIN
Published: December 2008

Somatostatin has been shown to exert inhibitory actions on gastric acid secretion, gastrointestinal motility and on the release of gastrointestinal and pancreatic hormones. Furthermore, somatostatin is produced and stored in endocrine cells in the corporeal and antral parts of the stomach and in the pancreas, indicating that endogenous somatostatin might take part in the control of gastrointestinal and pancreatic functions. (For a review on the subjects see Efendic, Luft & Uvnäs‐Wallensten 1982.)
The adrenergic influence on intestinal secretion in cholera
Authors: CASSUTO JEAN , SJÖVALL HENRIK , JODAL MATS , SVANVIK JOAR , LUNDGREN OVE
Published: December 2008

The intestinal secretion in cholera is evoked via the action of the cholera toxin on the intestinal mucosa. We have recently presented evidence for the involvement of the enteric nervous system in the induction of this type of secretion (Cassuto et al. 1981). We have also shown that electrical or reflex activation of the sympathetic fibres to the small intestine (Brunsson et al. 1979, Sjövall et al. 1982) increases net fluid absorption in the normal small intestine via an α‐adrenergic effect. These two observations led us to investigate the possible effect of adrenergic receptor stimulation on cholera secretion.
Neonatal β‐endorphin and sexual behavior
Authors: MEYERSON B. J.
Published: December 2008

β‐Endorphin (β‐END) has been found to decrease copulatory behavior in male rats (Meyerson & Terenius 1977). This effect appears within 10 min, lasts for about an hour and is also exerted after castration with subsequent testosterone substitution (Meyerson 1981). In addition, β‐END is known to influence neuroendocrine functions (for ref., see van Vugt & Meites 1980). Observations hitherto suggest that β‐END influences copulatory behavior rather by a direct central nervous action than as a secondary effect to altered endocrine secretion.
Responses of intradental nerve fibres to stimulation of dentine and pulp
Authors: NÄRHI M. V. O. , HIRVONEN T. J. , HAKUMÄKI M. O. K.
Published: December 2008

In the present work responses of intradental nerve fibres to stimuli that induce fluid flow in dentinal tubules as well as to direct mechanical irritation of the exposed pulp were studied on 9 young adult beagle dogs. Under pentobarbitone anesthesia 31 single functional intradental fibre units were dissected from the mandibular nerve. Stimuli were applied to the lower left canine tooth. Exposed dentine surface was irritated by scraping, air blasts and dry absorbent paper and the pulp mechanically with a von Frey hair. Ten fibre units responded to stimulation of dentine. Six of them were also tested with mechanical irritation of the pulp and were all responsive. Fifteen of twenty fibres responded to mechanical stimulation of the pulp. The mechanosensitive nerve fibres were all A‐type according to conduction velocities (mean 25.6±8.1 (SD) m/s). It is concluded that there exist mechanosensitive intradental A‐nerve fibres in the dog which are activated by stimuli that induce fluid flow in dentinal tubules. Nerve fibres of this type could be responsible for dentine sensitivity in man. Consequently, the present study gives support to the hydro‐dynamic hypothesis of dentine sensitivity. Moreover, mechanosensitive nerve fibres could also be responsible for the pain symptoms of pulpal inflammation, because pulpitis may also create suitable circumstances for their activation.
Mechanical restitution of the rat papillary muscle
Authors: RAGNARSDÓTTIR KRISTÍN , WOHLFART BJÖRN , JÓHANNSSON MAGNÚS
Published: December 2008

The experiments were performed on isometrically contracting rat papillary muscles paced at 1.0 Hz and at a temperature of 37°C. The contractile response of a test contraction continuously rose when the duration of the preceding stimulus interval was gradually increased from 0.2 s. A maximum value was seen at intervals of 60–120 s. This phenomenon was called mechanical restitution of the papillary muscle. The insertion of a priming beat before the test contraction in order to increase the amount of contractile calcium elevated the mechanical restitution curve but it did not change the maximum contractile force seen after 60–120 s intervals. Lowering the extracellular calcium concentration from 2.0 mM to 1.0 mM, however, depressed this maximum contractile force to about 50%. The mechanical restitution is thought to reflect inflow of activator calcium to a cellular store, from which it is later released in response to the action potential. By using two test contractions a simple method is described to estimate the recirculating fraction of activator calcium between beats in this preparation. In 11 preparations the recirculating fraction of activator calcium was 0.72±0.03 (mean ± SE). The results are consistent with the view that the same model of metabolism of activator calcium as previously proposed for rabbit papillary muscles is also applicable to the rat heart.
Effects of neurotensin on the transit of gastrointestinal contents in the rat
Authors: HELLSTRÖM P. M. , NYLANDER G. , ROSELL S.
Published: December 2008

In this study the influence of neurotensin on gastric emptying, transit of gastrointestinal contents and ileo‐cecal emptying was studied in the conscious rat. A bolus of radioactive marker was deposited in the gastrointestinal lumen and was monitored at different time intervals during its passage along the bowel. Gastric emptying was inhibited in a dose‐dependent manner by i. v. infusion of 6 and 12 (p<0.01) pmol × kg‐1× min‐1 of neurotensin. The transit of the gastrointestinal contents was retarded by 3 (p<0.001) and 6 (p<0.001) pmol × kg‐1 x min‐1. In addition, at 12 pmol × kg‐1× min‐1 the distribution of the radioactivity was spread out and the radioactive front migrated farther. Infusion of 6 pmol × kg‐1× min‐1 of neurotensin also produced spreading of the radioactivity in the intestine with proximal pooling and rapid migration of the front of the radioactive bolus (p<0.001). Ileo‐cecal emptying was inhibited by neurotensin at 6 pmol × kg‐1× min‐1, with pooling of the radioactivity proximal to the ileo‐cecal valve (p<0.001). These data indicate that neurotensin prolongs the transit time of the chyme in the stomach and small intestine. Thus, neurotensin may facilitate thorough digestion of the chyme in the small intestine and enhance the absorption of nutrients.
Reflex control of cat extrinsic and intrinsic tongue muscles exerted by intraoral receptors
Authors: HELLSTRAND ERIC
Published: December 2008

The effects of mechanical and noxious stimulation of the palatal and lingual surfaces on the activity of the extrinsic and intrinsic tongue muscles have been studied in cats. Stimulation of the hard palate produced mainly activation of extrinsic tongue muscles while inhibition was elicited by stimulating the soft palate. Longlasting pressure on the hard palate caused rhythmic tongue flapping by intermittent genioglossal activity. The intrinsic tongue muscles, m. transversus and m. verticalis, were activated by noxious stimuli applied to the hard palate, the effects apparently being mediated by high‐threshold afferents. Mechanical and noxious stimulation applied to the dorsal and ventral lingual surfaces of the tongue either activated or inhibited the extrinsic tongue muscles depending on the reflex area stimulated. The intrinsic tongue muscles were activated by noxious stimuli applied to the tongue surfaces. The anastomoses running between the hypoglossal and lingual nerves were found to mediate mainly nociceptive afferent impulses travelling from the hypoglossal to the lingual nerve. The intrinsic muscles were found to be controlled by anastomosal nociceptive afferents.
Enhancement of insulin secretion during selective blockade of α1, ‐ and α2‐adrenoceptors in the rat: Effects of somatostatin
Authors: AHRÉN BO , JÁRHULT JOHANNES , LUNDQUIST INGMAR
Published: December 2008

The effects of somatostatin on plasma concentrations of insulin and glucose in the presence of the selective α1‐adrenoceptor blocking agent prazosin or the selective α2‐adrenoceptor blocking drug yohimbine were studied in vivo in anesthetized rats. Infusion of both prazosin (0.080 mg/min) and yohimbine (0.018 mg/min) increased plasma insulin levels within 10 min. Prazosin, but not yohimbine, caused a significant increment in plasma glucose concentration. Somatostatin (0.1 μg/min) promptly and extensively lowered plasma insulin concentrations during the infusion of both prazosin and yohimbine, suggesting that the inhibitory effect of somatostatin is not mediated via a direct action on α1or α2‐adrenoceptors. Plasma glucose concentration fell slightly during somatostatin administration. A marked increment in insulin release occurred in response to cessation of the somatostatin infusion, both during prazosin‐ and yohimbine‐treatment. We conclude that somatostatin efficiently inhibits insulin secretion during selective α1‐ and α2‐adrenoceptor blockade and, further, that the insulin off‐response after somatostatin treatment is potentiated by α‐adrenoceptor blockade. This study also indicates that blockade of α1‐ as well as of α2‐adrenoceptors leads to an increased insulin secretion.
Distribution of some non‐physiological amino acids (AIB, DAB, MeAIB) in mice
Authors: APPELGREN LARS‐ERIK , LINDQVIST INGER , NILSSON OVE , RONQUIST GUNNAR
Published: December 2008

The distribution of labelled 2‐aminoisobutyric acid (AIB), 2, 4‐diaminobutyric acid (DAB) and 2‐(methylamino)‐isobutyric acid (MeAIB) was studied by whole body autoradiography in mice. All the amino acids were rapidly cleared from the blood and were taken up in most of the organs in the body. The results suggest the presence of operating transport systems for these amino acids into the majority of different cell types in mice. In the central nervous system, small amounts could be registered and in the pancreas there was a marked difference between DAB, which was not taken up, and the other two amino acids which were heavily accumulated. In an early embryo only Me AIB was observed in a high concentration.
Secretion of 3H‐acetylcholine from guinea‐pig ileum myenteric plexus is enhanced by 8‐Br adenosine 3‘,5’‐cyclic monophosphate but not changed by 8‐Br guanosine 3‘,5’‐cyclic monophosphate
Authors: ALBERTS P. , STJÄRNE L.
Published: December 2008

The acetylcholine (ACh) stores of cholinergic neurons of the myenteric plexus of guinea‐pig ileum were labelled by preincubation with 3H‐(methyl)‐choline. The secretion of labelled transmitter evoked by electrical field stimulation at 1 Hz in the presence of eserine increased by 55% after addition of 0.5 mM 8‐Br adenosine 3‘,5’‐cyclic monophosphate (8‐Br cAMP). Atropine further enhanced the secretory response, but not more than in the absence of 8‐Br cAMP. 8‐Br guanosine 3‘,5’‐cyclic monophosphate (8‐Br cGMP, 0.5 mM) did not change the secretory response to 0.5 or 1 Hz stimulation, either at 1.8 mM or at 0.6 mM calcium, in the absence of eserine. Nor did 1 mM 8‐Br cGMP alter the effects of atropine or of oxotremorine. Activation of guanylate cyclase by 0.1 mM N‐methyl‐N‘‐nit‐ro‐N‐nitroso guanidine failed to alter the secretory response to 0.5 Hz stimulation in the absence of eserine, or to influence the depression of the secretion caused by oxotremorine. The phosphodiesterase inhibitor 3‐isobutyl‐1‐methylxanthine (1 mM) neither altered the secretory response in the presence of eserine, nor the enhancing effect of atropine. The results suggest that cyclic nucleotides are probably not critically involved as “second messengers” in the muscarinic “autoinhibition” of ACh secretion from cholinergic myenteric neurons of guinea‐pig ileum.
Protective value of sympathectomy of the ear in noise
Authors: BORG ERIK
Published: December 2008

Noise‐induced hearing loss was assessed in unilaterally sympathectomized rats exposed one month to 100 dB Leq(lin) noise. The systolic blood pressure of these animals was in the range of 110–140 mmHg. Auditory sensitivity was determined electrophysiologically by brainstem response audiometry to 1/3‐octave filtered clicks. The results showed that the loss of sensitivity was about 10 dB smaller (p<0.01) on the sympathectomized side. This observation may partially explain the individual differences in susceptibility to noise‐induced hearing loss and point towards protective measures and therapeutic possibilities through manipulation of sympathetic activity in the inner ear.
Peripheral nerve function in acute and chronic uremia in rats
Authors: TEGNÉR RICHARD , BRISMAR TOM
Published: December 2008

There is good evidence that uremic neuropathy is due to a dialysable toxin which causes a generalised and reversible slowing of the nerve conduction velocity (for review see Nielsen 1979). However, the toxin has not been identified and its mode of action is unknown. The present report describes the peripheral nerve function in acute and chronic experimental uremia.
Anoxia increases potassium conductance in hippocampal nerve cells
Authors: HANSEN A. J. , HOUNSGAARD J. , JAHNSEN H.
Published: December 2008

The effect of anoxia on nerve cell function was studied by intra‐ and extracellular micro‐electrode recordings from the CA1 and CA3 region in guinea pig hippocampal slices. Hyperpolarization and concomitant reduction of the nerve cell input resistance was observed early during anoxia. During this period the spontaneous activity first disappeared, then the evoked activity gradually disappeared. The hyperpolarization was followed by depolarization and an absence of a measurable input resistance. All the induced changes were reversed when the slice was reoxygenated. Reversal of the electro‐chemical gradient for Cl‐ across the nerve cell membrane did not affect the course of events during anoxia. Aminopyridines blocked the anoxic hyperpolarization and attenuated the decrease of membrane resistance, but had no effect on the later depolarization. Blockers of synaptic transmission, Mn++, Mg++‐ and of Na+‐channels (TTX) were without effect on the nerve cell changes during anoxia. It is suggested that the reduction of nerve cell excitability in anoxia is primarily due to increased K+‐conductance. Thus, the nerve cells are hyper‐polarized and the input resistance reduced, causing higher threshold and reduction of synaptic potentials. The mechanism of the K+‐conductance activation is unknown at present.