bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of intravenously administered catecholamines on cerebral oxygen consumption and blood flow in the rat
Authors: Berntman Leif , Dahlgren Nils , Siesjö Bo K.
Published: December 2008

In order to study effects of catecholamines on cerebral oxygen consumption (CMRo2) and blood flow (CBF), rats maintained on 75 % N2O and 25 % O2, were infused i.v. with noradrenaline (2, 5, or 8 μpg. kg‐1. min‐1) or adrenaline (2 or 8, μg. kg‐1.min‐1) for 10 min before CBF and CMRozwere measured. In about 50% of animals infused with 2–8,μg. kg‐1min‐1of noradrenaline, CMRoz(and CBF) rose. However, there was no dose‐dependent response, and CMRo2, did not exceed 150% of control. The effects of noradrenaline in a dose of 5 μg. kg‐l. min‐1on CMRo2, and CBF were blocked by propranolol (2.5μg.kg‐1). In animals infused with adrenaline (8 μg.kg‐1.min‐1) CMRo2, was doubled and, in many, CBF rose 4‐ to 6‐fold. It is concluded that, when given in sufficient amounts, catecholamines have pronounced effects on cerebral metabolism and blood flow, the effects of adrenaline on CMRo2, and CBF resembling those observed in status epilepticus.
The effect of vigorous physical activity at work on serum lipids with a special reference to serum high‐density lipoprotein cholesterol
Authors: Lehtonen A. , Viikari J.
Published: December 2008

Serum lipid concentrations of lumberjacks whose occupational physical activity is most vigorous were compared with those of electricians. The lumberjacks had significantly higher serum HDL‐cholesterol and significantly lower triglyceride and free fatty acid concentrations hut there were no significant differences in total cholesterol levels. The favourable effect of vigorous physical activity at work on lipid metabolism is, however, epidemiologically not seen, obviously due to negative risk factors in lumberjacks' life.
Isometric and dynamic endurance as a function of age and skeletal muscle characteristics
Authors: Larsson Lars , Karlsson Jan
Published: December 2008

The aim of the study was to investigate the influence of age on endurance of human skeletal muscle. An attempt was made to correlate muscular performance at various ages with some morphological and enzymatic characteristics of the muscle. Fifty healthy men, 22–65 years of age, with low daily physical activity (clerks) volunteered for the study. Isometric and dynamic endurance were determined under standardized conditions and measured in relation to maximum strength, thereby correcting for individual as well as age differences in maximum strength. Biopsies taken from the quadriceps muscle were used for muscle fibre classification, fibre area determinations, and measurements of some enzyme activities (Mg2+‐ stimulated ATPase, myokinase (MK), lactate dehydrogenase (LDH), LDH isozymes). Maximum isometric and dynamic strength decreased in the older groups while no significant change was seen in isometric or dynamic endurance. Significant correlations were observed between endurance and fibre type distribution, fibre areas, and LDH isozyme activities.
Hepatic triacylglycerol and fatty‐acid biosynthesis during hypoxia in vivo
Authors: Kinnula Vuokko L. , Savolainen Markku J. , Hassinen Ilmo
Published: December 2008

Hepatic fatty acid biosynthesis and the activity of phosphatidate phosphohydrolase, the rate‐limiting enzyme of triacylglycerol biosynthesis, were studied after hypoxic periods of 1 and 7 days under hypo‐bark conditions at 40.8 kPa. Phosphatidate phosphohydrolase activity increased 2‐fold in the soluble fraction of the liver after one day at 40.8 kPa, but had returned to normal by 7 days. This was accompanied by a significant increase in liver triacylglycerol and sn‐glycerol‐3‐phosphate. The phosphatidate phosphohydrolase activity increased continuously over 7 days in the pair‐fed controls, probably due to the restriction on food. Measured as in vivo incorporation of 3H2O into lipids, the hepatic fatty acid synthesis rate increased somewhat in acute hypoxia, but returned to normal values during 7 days of hypoxia. Plasma free fatty acids increased markedly after 24 h in the fasting controls (90 %) with a smaller increase in the hypoxic group (50%) due to peripheral lipolysis. Hepatic glycogen stores decreased in the hypoxic and fasting animals both after 1 and 7 days. It Is concluded that hypoxia induces the accumulation of fat into the liver at least partly as a consequence of an increase in phosphatidate phosphohydrolase activity in the soluble fraction of the liver.
Suppression of autonomic postganglionic discharges by pentobarbital in dogs, with or without endotoxemia
Authors: Halinen M. O. , Hakumäki M. O. K. , Sarajas H. S. S.
Published: December 2008

Initial effects of pentobarbital (8 mg/kg) on autonomic efferent and afferent discharge rates were studied in 26 dogs under morphine‐chloralose anesthesia. Half of the dogs were given endotoxinE. coli(1 mg/kg) before pentobarbital. The postganglionic cervical vagal efferentation of all the dogs decreased as did the postganglionic cardiac sympathetic efferentation. The heart rate of the dogs given endotoxin decreased, while an increase in heart rate with abolition of respiratory arrhythmia, was observed in dogs without endotoxin. The aortic pressure of the former dogs dropped while it fell only slightly in the latter ones. The aortic arch baroreceptor activity decreased while the changes of left atrial B‐type receptor activity were not significant. The changes of the left atrial and central venous pressures were slight hut thosc of the pulmonary arterial pressure generally paralleled the changes in the aortic pressure. Pentobarbital, accordingly, seems to exert both sympatholytic and vagolytic effects. These explain the heart rate changes, as well as the impaired cardiac contractility it evokes. The obvious impairment of cardiovascular control mechanisms by pentobarbital should be seriously considered in investigations into the cardiovascular control.
Effect of lowering of the temperature on the tissue levels of cAMP, cGMP, PGE and PGF2β, in spontaneously beating rat atria preparation
Authors: Parantainen J. , Metsä‐Ketelä T. , Vapaatalo H.
Published: December 2008

Tissue levels of cAMP, cGMP, PGE, and PGF2βwere measured in spontaneously beating rat atria preparation at 20°C and 37°C. At 20°C the formation of cAMP increased in correlation with the markedly increased amplitude and reduced frequency. The other biochemical parameters were not significantly affected by the low temperature.
Effects on fluid balance induced by non‐febrile intracerebroventricular infusions of PGE2, PGFZ2β, and arachidonic acid in the goat
Authors: Leksell L. G.
Published: December 2008

Prostaglandins (PG) E2, F2α(30 ng/kg.min‐1) and arachidonic acid (150 and 300 ng/kg.min‐1) were infused for 30 min into the lateral cerebral ventricle of conscious hydrated and non‐hydrated goats. Like previously shown as concerns PGE1. PGE2was found to inhibit the water diuresis and cause some increase in the renal sodium excretion in the hydrated animal, and to elicit thirst in the non‐hydrated goat. The effects of PGE2were enhanced when hypertonic (0.25 M) NaCl was simultaneously infused into the ventricle. The antidiuretic effect of PGF2α, was less pronounced, and drinking only occasionally occurred when this PG was infused into the non‐hydrated animal. Only a weak, post‐infusion reduction of the water diuresis was observed when arachidonic acid was administered into the hydrated goat. Neither the PG:s, nor arachidonic acid affected the temperature regutation of the animals. The possibility is discussed that the lack of febrile response was due to the choice of platinum‐iridium as material for the cerebral irnplantations. It is suggested that PGE, might have interacted with CSF Na+in stimulating juxtaventricular receptors involved in the control of fluid balance. The experiments do not support the concept that PG:s of the E series constitute a cerebral humoral link in pyrogen‐induced fever.
The effects of ureteral occlusion and renal venous constriction on kidney kallikrein‐kinin and prostaglandin systems in dogs
Authors: Olsen Uffe Bang
Published: December 2008

Olsen, U. B. The effects of ureteral occlusion and venal cenous constriction on kidney kallikrein‐kinin and prostaglandin systems in dogs. Acta physiol. scand. 1978. 104. 443–452.

The intrarenal pressure was raised to 40–50 mmHg by ureteral occlusion or by renal venous constriction in anesthetized dogs loaded with 10% mannitol in saline and with a urine flow of approximately I ml/min/ kidney. Both manoeuvres produced vasodilation and decreased urine creatinine excretion (GFR). Ureteral occlusion was associated with a marked antinatriuresis, which contrasted the variable decrements in sodium excretion during renal venous constriction. Ureteral occlusion did not affect urine excretion of kallikrein or kinins, whilst renal venous constriction decreased urinary kallikrein excretion, yet markedly increased urinary kinin excretion. Ureteral occlusion and renal venous constriction comparably increased urine prostaglandin (E‐like) excretion by a presumably pressure dependent mechanism. Inhibition of prostaglandin synthesis by indomethacin abolished the vasodilation during renal venous constriction and this was accompanied by marked reductions of urinary creatinine (GFR) and kallikrein excretions. whilst the kinin excretion was enhanced as observed before the administration of indomethacin.
Phosphorylation of endogenous proteins by endogenous protein kinase of density gradient—purified plasma membrane vesicles of Ehrlich cells
Authors: Ronquist Gunnar , ÂGren Gunnar , Lindqvist Inger
Published: December 2008

A phosphorylation of endogenous acceptor protein(s) has been demonstrated to occur in membraneous vesicles prepared from Ehrlich ascites tumour cells. The reaction was catalyzed by endogenous protein kinase in the présence of exogenous (γ32P)ATP. A considérable increase of the spécifie protein kinase activity took place when the plasma membrane préparation was subjected to a further gradient centrifuga‐tion in Dextran T 150. This was done in the présence of a slightly alkaline phosphate buffer containing Mg‐ions which resulted in the formation of a well defined vesicular préparation at density 1.035 in the gradient. The apparent Km and Vmax for the reaction with vesicles and exogenous (γ32P)ATP were deter‐mined and found to be 0.022 mM and 0.23 nmol × mg‐1× 10 min‐1, respectively. Neither cyclic AMP nor cyclic GMP did stimulate the protein kinase‐catalyzed reaction. Instead, a clear inhibition of the reaction by the cyclic nucleotides was unexpectedly registered. Adenosine at 0.5 mM also inhibited the reaction. Calcium ions were inhibitory at ail concentrations tested in the présence of a fixed (γ32P)ATP/Mg2+ ratio. When Mg‐ions were stoichiometrically replaced by Ca‐ions practically no activity was observed.
Progesterone effects on the evolution of myometrial activity in vivo in the non‐pregnant rabbit
Authors: BATRA S. , ÅKERLUND M. , LAUDANSKI T.
Published: December 2008

In order to study the influence of progesterone on the myometrial activity ovarian secretion of progesterone was stimulated by intravenous injection of human chorion gonadotrophin (HCG, 75 IU) in 9 nonpregnant rabbits. 4 rabbits, used as controls, were given only saline. Plasma progesterone concentration in blood samples taken at frequent intervals (2–4 h) during the recording was measured by radioimmunoassay. In the controls, the myometrial activity and the plasma levels of progesterone did not change. After 1 h of HCG administration the amplitude of contraction began to decrease and the frequency began to increase after 3 h. After about 5 h the changes in amplitude and frequency were generally fully developed. This pattern of myometrial activity persisted throughout the recording period (12 h) and was also present in recordings made after 24 and 48 h of HCG injection. A maximal increase in plasma progesterone concentration (5.0 ng/ml) had already occurred by 2 h after the HCG injection and gradually decreased thereafter. It is concluded that an elevation in the level of progesterone in non‐pregnant rabbits resulting from increased ovarian output (through HCG) has a pronounced and immediate depressing effect on the character of myometrial activity which is indicative of a shift from nonpregnant to pregnant type.
Effects of indomethacin on regional blood flow in conscious rabbits—a microsphere study
Authors: BILL ANDERS
Published: December 2008

In an attempt to reveal the importance of prostaglandins in the control of regional blood flow 20 mg/kg b.wt. indomethacin was giveni.v.in conscious resting rabbits. Regional blood flow determinations were made before and 20 min after the injection using the labelled microsphere technique. The blood flow in the stomach wall was reduced by 0.75 ± 0.17 g·min‐1·g‐1from a level of 1.64 ± 0.24 g·min‐1·g‐1. In jejunum the corresponding figures were 0.44 ± 0.12 and 1.26 ± 0.17 and in the brain 0.29 ± 0.10 and 1.24 ± 0.10. The blood flow in the liver via the hepatic artery increased by 0.20 ± 0.02 g·min‐1·g‐1from a level of 0.13 ± 0.02 g·min‐1·g‐1. In the retina there was a reduction in blood flow by 2.75 ± 1.03 mg·min‐1from a starting level of 15.1 ± 2.3 mg·min‐1. In a number of other tissues investigated there were no significant effects of the drug. The results suggest that under resting conditions prostaglandins play a role in the control of blood flow in the gastrointestinal tract, the brain and the retina—tissues which are likely to be rather active under such conditions.
Plasma catecholamines, cyclic AMP and metabolic substrates in hemorrhagic shock of the rat. The effect of adrenal demedullation and 6‐OH‐dopamine treatment
Authors: FREDHOLM BERTIL B. , FARNEBO LARS OVE , HAMBERGER BERTIL
Published: December 2008

Plasma catecholamines, cyclic AMP and metabolic substrates in hemorrhagic shock of rats was studied in 4 groups of animals: 1) Control rats, 2) rats with adrenal demedullation, 3) rats with 6‐OH‐dopamine induced chemical sympathectomy, and 4) rats with combined demedullation and sympathectomy. The rats were bled to a systemic blood pressure of 35 mmHg.

The basal plasma level of noradrenaline (NA), adrenaline (A) and dopamine (DA) in control animals was each about 1 nmol/1. After hemorrhage for 1 h the A levels had reached 50 nmol/1 and there was little further rise after 4 h. The rise was eliminated by demedullation but unaffected by sympathectomy. NA levels rose continuously in the control and in the sympathectomized rats. At 1 h the level was about 4 nmol/1 and at 4 h about 20 nmol/1. The demedullated rats showed a 3‐fold increase in circulating NA, while little or no change was seen in the combined demedullated and sympathectomized rats. DA levels did not change in any of the groups during the first hour, but were markedly elevated after 4 h of hypotension.

Cyclic AMP and glucose levels in plasma showed a rapid increase 1 h after hemorrhage and thereafter returned to or below basal values. Demedullation largely prevented the increase, while sympathectomy had no effect. The increase in lactate and pyruvate levels were diminished but not eliminated by either sympathectomy or demedullation. Glycerol levels were unchanged and FFA decreased in all groups of rats.

The results show that the adrenal medulla is the dominating source of plasma catecholamines in hemorrhagic shock in rats. The initial increase in plasma glucose and cyclic AMP appear to be largely mediated by adrenal A. The subsequent fall in these parameters and derangement of circulatory homeostasis are not, in the present shock model, primarily due to a failure of catecholamine secretion, but rather to a decreased responsiveness of peripheral tissues to catecholamine stimulation.
Respiratory and circulatory responses to sustained positive‐pressure breathing and exercise in man
Authors: Bjurstedt H. , Rosenhamer G. , Lindborg B. , Hesser C. M.
Published: December 2008

To investigate the effects of sustained positive‐pressure breathing (PPB) on the adaptation of respiratory and circulatory functions to exercise, 8 healthy volunteers were exposed to PPB of air at 15 and 30 cm H2O in the supine position at rest and while performing leg exercise at 50% of individual maximal working capacity. PPB was both subjectively and objectively better tolerated when combined with exercise than it was at rest. PPB at 30 cm HaO resulted in marked hyperventilation with alkalosis in the resting condition, but did not significantly affect respiratory minute volume, blood gases or acid‐base balance during exercise. Cardiac output and left ventricular work were reduced by about one fifth and one third, respectively, both at rest and during exercise. In contrast to the case at normal airway pressure, exercise‐induced increase in cardiac output was accompanied by an increment in stroke volume during PPB. Although mean arterial pressure (relative to atmospheric) was elevated by PPB at rest and during exercise, the driving pressure in systemic circuits (arterial minus central venous pressure) was reduced in both conditions. It is concluded that dynamic exercise counteracts deleterious effects of PPB by normalizing respiratory function and by improving cardiac filling by activation of the leg muscle and the abdominal pumps.
Uptake and release of adenosine in isolated rat fat cells
Authors: FREDHOLM BERTIL B. , HJEMDAHL PAUL
Published: December 2008

Radioactively labelled adenosine and adenine were rapidly taken up by isolated rat fat cells, and incorporated into nucleotides, of which ATP dominated. The overall process had an apparent Kmof 1–5 μM. During incubation, especially in the presence of lipolytic agents, there was a reduction in labelled ATP with a compensatory increase in ADP, AMP, cAMP and nucleosides. The build‐up of adenosine during incubation was inhibited by theophylline, which inhibits 5′‐nucleotidase. Radioactivity released from perifused fat cells consisted mainly of nucleoside material, of which adenosine predominated. Lipolytic stimulation caused no significant increase in nucleoside outflow from perifused cells, whereas oxygenation was capable of reducing this outflow. It is concluded that adenosine is formed by fat cells as a consequence of ATP breakdown. Stimulation of lipolysis during activation of the sympathetic nerves leads to reversible ATP breakdown and adenosine release. Adenosine might therefore act as a modulator of lipolysisin vivounder these conditions, even though it does not serve as a feed back regulator in the proper sense.
Cardiac receptors with non‐medullated vagal afferents in the rat
Authors: THORÉN PETER , NORESSON EDDY , RICKSTEN SVEN‐ERIK
Published: December 2008

The characteristics of 22 atrial receptors in 15 normotensive adult male Wistar rats were investigated. AH the receptor afferents were included in the C‐fibre group with conduction velocities from 0.4 to 1.2 m/sec. No atrial medullated receptors or ventricular C‐fibre endings were found. Two receptors were located in right atrium and 2 receptors throughout left atrium. Upon elevation of the left atrial pressure the receptor discharge was markedly elevated with thresholds from 2.5 to 9 mmHg in mean left atrial pressure. Ten of the atrial receptors displayed a clear cardiac rhythmicity upon activation and the discharge correlated with the v‐wave, indicating distension as the cause of receptor activation. The maximal firing rate in most receptors was very high (up to 70 Hz), but 8 receptors had maximal firing rates below 25 Hz. These low frequency receptors had higher threshold and showed a more irregular firing. Thus, there is a substantial population of atrial receptors with vagal non‐medullated afferents in the rat heart and the thresholds for many of these receptors are so low that they are likely to be active during normal conditions.
The effect of water temperature on the hormonal response to prolonged swimming
Authors: GALBO H. , HOUSTON M. E. , CHRISTENSEN N. J. , HOLST J. J. , NIELSEN B. , NYGAARD E. , SUZUKI J.
Published: December 2008

The relationship between thermoreception, hormonal secretion and muscular activity was studied. 6 men swam 60 min in 21, 27 and 33°C water at a speed requiring 68 % of Voa max (determined in 27°C water). Rectal temperature increased in 33°C (1.3 ± 0.2°C, mean and S.E.) and 27°C (0.7 ± 0.1°C) expts. but decreased in 21°C expts. (0.8 ± 0.3°C). Changes in esophageal and muscle temperatures parallelled changes in rectal temperature. Plasma noradrenaline was higher in 33°C than in 27°C expts. and growth hormone, Cortisol and glucagon concentrations increased in 27°C and 33°C expts. only. Insulin concentrations were uniformly depressed during swimming at the different water temperatures. In 21°C expts. noradrenaline and adrenaline concentrations were higher than in 27°C expts. VO2, carbohydrate combustion and peak lactate were slightly lower in 33°C expts. Plasma glucose decreased slightly and FFA and glycerol concentrations increased identically in all expts. Heart rate increased continuously during swimming in 27°C and 33°C expts., but not in 21°C expts. In conclusion the rise in body temperatures normally observed during exercise enhances the exercise induced increases in the plasma concentrations of noradrenaline, Cortisol, growth hormone and glucagon. Decreased body temperatures may elicit catecholamine secretion as a direct consequence of thermoreception. Shivering may account for previously observed decreases in insulin secretion during cold stress but not for increases in Cortisol and growth hormone.
The influence of calcium on morphology and histamine content of isolated intact rat mast cell granules
Authors: ANDERSON PER , RÖHLICH PÁL , UVNÄS BÖRJE
Published: December 2008

Histamine is released by “sequential exocytosis” in mast cells. The exocytosis involves fusion of the plasma membrane with the perigranular membrane and further fusions of adjacent perigranular membranes. To study a possible direct effect of Ca2+on granule membrane fusions, mast cell granule suspensions were prepared from sonicated rat mast cells. With the sonication method used, more than 60% of the granules obtained were found to be homogeneous, electron dense and surrounded by a perigranular membrane, when observed in the electron microscope. These granules correspond to normal, histamine‐containing granules found in untreated mast cells and are therefore named “intact” granules. The other granules were swollen, less electron dense and without a perigranular membrane. These “changed” granules are formed during the histamine release process. Aliquots of the granule suspension were incubated in 0.34 M sucrose buffered with 10 mM HEPES, pH 7.0, containing different concentrations of CaCl2, MgCl2(10 mM, 1 mM, 100 μM, 10 μM) or NaCl (10 mM). Only with the highest concentration (10 mM) of Ca2+or Mg2+was it possible to visualize an apposition of the perigranular membranes of “intact”, normal granules. No elimination of the individual membrane structures could be observed at the place of membrane contact. Thus, we found no signs of membrane fusions. The histamine content was lower in the suspensions incubated with lower concentrations of these ions or with 10 mM NaCl. Ca2+and Mg2+in high concentrations seemed to stabilize the perigranular membranes instead of initiating histamine release. Therefore, changes in the Ca2+‐ion concentration per se do not explain the membrane fusions seen in mast cells during “sequential exocytosis”.
Fasting and prolonged exercise increase vasoactive intestinal polypeptide (VIP) in plasma
Authors: GALBO H. , HILSTED J. , FAHRENKRUG J. , De MUCKADELL O. B. SCHAFFALITZKY
Published: December 2008

6 young men had venous blood drawn during 4 experiments. The concentration of VIP in plasma increased markedly (from 1.8 (0–4.5) to 22.3 (7.8–43.8) pmol‐1−1, mean and range) during 3 h of mild bicycle exercise but not at all during an equivalent period of rest or during short term submaximal and maximal exercise. During 59 h of fasting, VIP increased from 3.6 (0.6‐6.6) to 10.2 (6.6–13.8) pmol‐1−1 (p < 0.05). The concentration of glucose in plasma decreased significantly during the prolonged exercise as well as during fasting. The known metabolic actions of VIP and the demonstrated increases in its plasma concentration during negative energy balance indicate that VIP is “a polypeptide of substrate need”.
Evidence for a cholinergic secretory innervation of the guinea–pig endometrium
Authors: HAMMARSTRÖM MARGARETA , SJÖSTRAND NILS O.
Published: December 2008

Uterine mucus secretion was studied by measuring carbohydrate release from everted guinea–pig uteri placed in organ baths. Field stimulation of the organ resulted in a significant increase in carbohydrate out–put, this increase was inhibited by tetrodotoxin, scopolamine and previous destruction of the paracervical ganglia. Previous section of the hypogastric nerve reduced the response to field stimulation, while interruption of the costouterine connexion or the pelvic nerve was without overt effect. Stimulation of the hypogastric nerve increased uterine carbohydrate secretion. Pelvic nerve stimulation produced no significant effect. Carbachol increased the carbohydrate secretion to the same extent as did field stimulation. Isoprenaline and methoxamine were without significant effect. It is suggested that certain endometrial cells have a cholinergic sympathetic secretory innervation with pre– and postganglionic fibers running in the hypogastric nerve.
The effect of noise on cochlear blood flow in the conscious rabbit
Authors: HULTCRANTZ ELISABETH
Published: December 2008

The cochlear blood flow was measured with the microsphere method in unanesthetized rabbits, prior to and during noise–exposure. Different sound pressure levels were used: 100 dB, 115 dB and 120 dB. Some of the animals had the cervical sympathetic trunk cut unilaterally. The effects of the delivered noise on the organ of Corti were studied in other rabbits with scanning electron microscopy. In spite of ultrastructural changes indicating damage of sensory cells after 115 dB and 120 dB exposure no changes of the total cochlear blood flow could be observed. After unilateral section of the cervical sympathetic trunk the cochlear blood flow was less on the intact side (25 %) already prior to noise exposure and the difference was not significantly affected by noise. Different sizes of microspheres were used: 8.2, 8.4, 8.7, 9.2 μAm. The 8.2 and 8.4 μ m–spheres seemed well fitted for measurements of cochlear blood flow but passed the cerebral capillaries to a high extent. Control experiments using both 8.2/8.4 μ m–spheres and 15 μ m–spheres were performed and the degree of passage in different tissues was estimated.
Prostacyclin‐dependent coronary vasodilation in rabbit and guinea pig hearts
Authors: WENNMALM ÅKE
Published: December 2008

Isolated hearts from rabbits or guinea pigs were perfused according to Langendorff and the coronary flow was recorded continuously. In addition, the rabbit heart transmyocardial effluent's content of platelet anti‐aggregatory (prostacyclin‐like, PCLA) activity was assayed biologically at regular intervals. Perfusion was performed with a solution gassed with 95% O2in CO2, switching at intervals to a solution gassed with 12% O2and 5% CO2in N2. Perfusion with a hypoxic solution elicited reproducible increases in coronary flow. After pretreatment with indomethacin (5times 10‐5M), this increase was completely abolished and in several cases it was reversed to a marked reduction in coronary flow. The transmyocardial effluent contained, during perfusion with normoxic solution, no detectable or only negligible amounts of PCLA. During hypoxia the efflux of PCLA into the transmyocardial effluent increased markedly. This increase was completely abolished wheri indomethacin (5 × 10‐5M) was added to the solution perfusing the heart. The results strongly suggest that increased coronary vascular formation of prostacyclin plays a key role in the coronary vasodilation induced by hypoxia in rabbit and guinea pig hearts.
Effects of diethyl‐stilboestrol on single fibres of frog skeletal muscle
Authors: KHAN A. R.
Published: December 2008

The effects of diethyl‐stilboestrol (DES), one of the most potent estrogens, were studied on single muscle fibres of the frog. In relatively low concentrations (5 μM), DES greatly potentiates the twitch response of the fibre without significantly affecting the amplitude of the tetanus response. The twitch potentiation is accompanied by an increase in time to peak tension and a marked prolongation of the relaxation phase. In tetanic response the half decay time after the last stimulus is also prolonged by DES. DES causes no changes in the resting or action potential of the muscle fibre. The S‐shaped curve relating peak contracture tension and caffeine concentration is shifted towards lower caffeine concentrations by DES. Dantrolene greatly suppresses the DES potentiated twitch. It is concluded that DES potentiates the twitch response and prolongs the relaxation time by inhibition of the calcium re‐uptake by the sarcoplasmic reticulum.
The effect of surgical sympathectomy and of neonatal treatment with 6‐hydroxydopamine and guanethidine on particle‐bound noradrenaline and35S‐sulphomucopolysaccharides
Authors: BLASCHKE ELEONORA , UVNÄS BÖRJE
Published: December 2008

Five to six weeks after bilateral stellate ganglionectomy, noradrenaline (NA) levels in cats' atria were reduced to ∽ 20% of controls. In vivo uptake of3H‐NA and of35S‐sulphate into gradient fractions containing noradrenergic vesicles from the atria decreased to ∽30% and ∽40%, respectively. The uptakes of3H‐NA and35S‐sulphate were significantly correlated in both control and ganglionectomized cats, and the distributions of3H and35S on the gradients were parallel. The findings suggest that sulphomucopolysaccharides (SMPSs) may be localized in noradrenergic vesicles, possibly participating in the storage of NA. In 10‐week‐old rats treated neonatally with either 6‐hydroxydopamine (6‐OH‐DA) or guanethidine, levels of NA in the heart, spleen and salivary glands were decreased to <10% and to 10–20%, respectively; in the seminal ducts to 33% and 45%, respectively.3H‐NA uptake into noradrenergic‐vesicle‐enriched subcellular fractions from the heart, spleen and salivary glands of 6‐OH‐DA treated rats decreased almost to the extent of NA depletion but in the seminal ducts the decrease was less marked. Guanethidine treatment left the uptake unaffected, except for the spleen. The discrepancy between storage and uptake suggests that surviving neurons display during their outgrowth into tissues a high uptake capacity but lack full NA synthesis.35S‐sulphate incorporation into non‐lipid compounds, presumably SMPSs, in the noradrenergic‐vesicle‐enriched fractions appeared unaffected or increased over corresponding control levels, possibly due to high synthetic activity in the growing neurons.
Anaphylaxis in the monkey: hemodynamics and blood flow distribution
Authors: SMEDEGÅRD GÖRAN , REVENÄS BJÖRN , ARFORS KARL‐E.
Published: December 2008

Aggregate anaphylaxis was induced in eight ovalbumin‐sensitized monkeys (Macaca irus). Hemodynamics, blood flow distribution and myocardial performance were studied. Following challenge, severe circulatory shock developed. Systemic arterial and left atrial pressures decreased and pulmonary arterial and right atrial pressures increased. There was a tenfold increase in pulmonary vascular resistance, and cardiac output was markedly reduced (‐75%). A redistribution of the blood flow to vital organs (brain, heart and liver) occurred, at the expense of flow to other regions (muscles, kidneys, pancreas and spleen). There was also a redistribution of the blood flow within the myocardium, resulting in an unchanged right ventricular blood flow, despite a decrease in total myocardial blood flow. Right ventricular stroke work was reduced in spite of high filling pressures, whereas the decrease in left ventricular stroke work coincided with low filling pressures. It is concluded that the initial main cause of the low outflow state was an increased resistance in the pulmonary circulation followed by acute right heart failure.
Analysis of the length response to a force step in smooth muscle from rabbit urinary bladder
Authors: HELLSTRAND PER , JOHANSSON BÖRJE
Published: December 2008

Responses to isotonic quick release of AC‐stimulated smooth muscle strips from rabbit urinary bladder were analysed. Releases were performed at the peak of contraction and at a preset tension level in the contraction and relaxation phase. In other expts. responses at 37°C and 27°C were compared. The length response always consisted of 3 parts: (1) elastic recoil, (2) rapid length change (isotonic transient), (3) steady length change. Qualitatively, phases (1)‐(3) could be distinguished also in responses to isotonic quick stretch. The immediate elastic recoils, phase (1), were described by exponential stress‐strain relations. Stiffness was found to be somewhat lower during relaxation than during contraction. No effect of temperature on the elastic recoil was seen. The initial velocity in phase (2) was 2–3 times greater than the velocity 100 ms after release. By means of computer analysis of the length records during phases (2) and (3) two decaying exponential processes with widely different time constants could be separated. The time constant of the faster process was of the order of 15–30 ms at 37°C. It decreased with increasing force steps and with increasing temperature. The amount of shortening associated with this process was correlated with the size of the force step, reaching a maximum of about 1.2% of the muscle length. The shortening velocities in phase (3), measured 100 ms after release, were described by Hill's equation. Vmax in the rising part and at the peak of contraction were 0.7 and 0.6 L/s respectively at 37°C. Lower values were found during relaxation and at 27°C. We suggest that part of the elastic recoil in phase (1) occurs in structures associated with the individual cross‐bridges, that phase (2) is dominated by a change in the distribution of conformations of bridges in the attached position and that the shortening rate in phase (3) is determined by the entire cycle of events during turnover of bridges after the muscle has adapted to the new load. Observations on the force response to length steps and on shifts from isometric to afterloaded isotonic contraction and vice versa are consistent with this interpretation.
Adaptive changes in cerebral blood flow and oxygen consumption during ethanol intoxication in the rat
Authors: HEMM1NGSEN RALF , BARRY DAVID I.
Published: December 2008

Cerebral blood flow (CBF) and oxygen consumption (CMRO2) were measured during acute and long‐term ethanol intoxication in the rat. The purpose was to investigate whether the adaptive changes (development of tolerance) occurring in the CNS during ethanol intoxication were associated with changes in CBF and/or CMRO2. Consistent with other studies we found that acute severe ethanol intoxication (median blood alcohol concentration (BAC=5.4 mg/ml)) caused a significant decrease in CBF and CMRO2. After 3–4 days of severe intoxication (BAC of 6.6 mg/ml) these physiological variables were less affected indicating that functional tolerance had developed: CMRO2and CBF during acute ethanol intoxication were 9.3 ml/100 g/min and 60 ml/100 g/min respectively; after the long term intoxication period these variables reached 11.2 ml/100 g/min and 78 ml/100 g/min respectively, i.e. values not significantly lower than those of the control group. After induction of hypercapnia (PaCO2about 80 mmHg) CBF increased by 360% in the control group; in the acutely intoxicated group CBF increased by only 127% and in the long term intoxicated group by 203 % indicating that the cerebrovascular CO2‐reactivity had also adapted to the ethanol intoxication. It is concluded that adaptive changes of the CNS to chronic ethanol intoxication comprise alterations in CMRO2, CBF and cerebrovascular reactivity.
Structural and functional ontogenetic development of the rat portal vein after neonatal 6‐hydroxydopamine treatment
Authors: LJUNG BENGT , LUNDBERG JAN M. , DAHLSTRÖM ANNICA , KJELLSTEDT ANN
Published: December 2008

The importance of the adrenergic vasomotor nerve supply for the vascular ontogenetic development has been studied in the isolated portal vein preparation from rats, at 5–6 weeks of age, who had either been chemically sympathectomized by a series of postnatal 6‐hydroxydopamine (6‐OHDA) injections or been receiving the solvent alone. It was found that 6‐OHDA treatment largely, but not completely, prevented the outgrowth of the terminal NA fluorescent ground plexus. Nevertheless, the media underwent a seemingly normal differentiation into two layers. Functionally, the portal vein from the 6‐OHDA treated animals displayed weak and non‐persistent myogenic spontaneous activity; sensitivity to exogenous noradrenaline (NA) was increased 3‐fold and maximum stress was increased by 25 % as compared to control. Responses to transmural field stimulation were only obtained at high impulse rates and the maximum response was attenuated. Considering the very sparse adrenergic innervation following 6‐OHDA they seemed surprisingly large, however, but since they were abolished by tetrodotoxin and by phenoxybenzamine responses are concluded to be neurogenic and adrenergic in origin. A singular attenuation of neurogenic responses by atropine was found in 6‐OHDA treated vessels but not in controls. It is concluded that the adrenergic vasomotor nerve supply seems to exert some trophic influence during ontogenetic development but that the morphologic vascular development is largely governed by other, non‐neurogenic mechanisms. As to functional development, 6‐OHDA induced sympathectomy causes impaired development of phasic myogenic activity whereas maximum stress is augmented as is the tissue sensitivity to exogenous NA.
Formation and action of prostacyclin in the isolated human umbilical artery
Authors: HAMBERG M. , TUVEMO T. , SVENSSON J. , JONSSON C.‐E.
Published: December 2008

The transformation of [l‐14C]arachidonic acid by homogenates of human umbilical arteries was studied. The major compund formed was the stable end product of PGI2, i.e. 6‐keto‐PGF1α (lactol form) as analyzed by gas‐liquid chromatography‐mass spectrometry. PGI2 was generated by incubating PGH2 with a lyophilized pig aorta microsome preparation. PGI2 concentrations around 10 ng/ml relaxed the human umbilical artery preparation significantly. Formation of PGI2 by umbilical arteries during pregnancy might be a mechanism for regulation of blood flow to the fetus.
Relationships between peak force, action potential duration and stimulus interval in rabbit myocardium
Authors: WOHLFART BJÖRN
Published: December 2008

Isometric force and membrane action potential were recorded simultaneously in rabbit papillary muscles (36.5o–37.5oC). One to three test stimuli were given at various intervals (0.20–10.0 s) after a series of control contractions at constant stimulation intervals (1.0–1.5 s). Optimum peak force always occurred when the preceding test interval was 0.80 s. When this interval was >0.80 s, time to peak force was a linear function of the action potential duration. Furthermore, under these conditions the action potential duration (AP1) and peak force (F1,) of the test contraction could be used to predict peak force (F2) of the subsequent contraction elicited after a fixed interval (0.80–1.50 s) according to the equation (regression plane):F2=BApAPt+BFF,+A.ConstantsBAPandflFare interpreted to provide information about calcium influx during the action potential and of the recirculation of calcium between contractions, respectively.F2deviated towards higher values than predicted from the equation when the preceding test contraction was triggered to occur at an interval &0.80 s. This may be due to an intensified calcium transport into the cell during the action potential after these short intervals. The action potential duration was inversely related to both the inotropic state of the muscle (representing a feed–back mechanism) and the preceding stimulation interval.
Myogenic microvascular responses to change of transmural pressure A mathematical approach
Authors: BORGSTRÖM PER , GRÄNDE PER–OLOF
Published: December 2008

The recently described static and dynamic myogenic responses in the sympathectomized skeletal muscle microvessels to a given transmural pressure (PT) change applied at different rates (dPTldt) (Grände & Mellander 1978), were further analysed in this study with a mathematical approach. The hypothesis that myogenic reactions are triggered by and related to wall tension was also tested. The mathematical model was based on a force–equilibrium in the microvessel wall including passive forces related to vascular transmural pressure, elasticity, and wall–viscosity, and active myogenic forces related to wall tension and its rate of change. Great resemblance was demonstrated between microvascular resistance curves obtained with the model and corresponding curves observed in vivo, indicating that the model quite adequately can describe myogenic microvascular resistance responses to transmural pressure stimuli. The results support the myogenic hypothesis in general and, in particular, the concept of an important rate–sensitivity in myogenic microvascular control and are compatible with the view that myogenic reactions are triggered by and related to change of wall tension. The model, in addition, provided data for certain microvascular variables which are difficult to assess by in vivo observations, e.g. Young's modulus of elasticity, wall tension, its rate of change, and internal vessel radius, and it offered a means to define more precisely the role of physical factors like effects of Poiseuille's and Laplace's laws in vascular resistance regulation.
Effects of duct ligation on choline acetyltransferase activity in salivary glands of rats
Authors: BANNS H. E. , EKSTROM J. , MANN S. P.
Published: December 2008

Duct ligation was found to cause a decrease in the weights of submaxillary and parotid glands examined 3 weeks postoperatively. Choline acetyltransferase activity in ligated glands was compared with that in unligated contralateral glands. The enzyme activity was also measured in the glands from both sides of unoperated control animals. Interference in the assay of choline acetyltransferase by other acetylated compounds was avoided by introducing suitable control incubations. Ligated submaxillary glands showed a small decrease in the activity of choline acetyltransferase both when compared with contralateral glands and with glands of control rats. In parotid glands the enzyme activity was found to be lower only when ligated and contralateral glands were compared. Structural changes in the nerves and reduced traffic of impulses in them may have to be considered as explanations for the reduction in enzyme activity in duct–ligated glands.
Blood flow in proximal femur of the dog determined by the local 133Xe injection method
Authors: LAHTINEN T. , ALHAVA E. M. , HAKUMÄKI M. , SKELÄlNEN J. JÄÄ , VÄÄNANEN A. , KARJALAINEN P.
Published: December 2008

A new approach for measuring blood flow in bone is presented. It consists of the local injection of 133Xe into the proximal femur of adult beagles and the external measurement of isotope washout curves. The curves were analyzed using a two–compartment exponential model. The half–times for the tracer washout from the fast and slow compartment were 3.34±0.48 min and 33.6±11.7 min (mean ±1 S.D.) respectively. Blood flow was calculated using a measured blood to bone partition coefficient of 1.55 ml/g. The mean blood perfusion in proximal femur of the dog was 10.8±4.3 ml/100 g/min (mean ± 1 S.D.). This value agrees well with most estimates of bone circulation. Due to rapid disappearance of 133Xe the method is easy to repeat and is thus suitable for physiological studies of local blood flow in bones.
Influence of neural and humoral beta–adrenoceptor stimulation on dynamic myogenic microvascular reactivity in cat skeletal muscle
Authors: GRÄNDE PER–OLOF
Published: December 2008

Analysis of myogenic microvascular reactivity in terms of its recently described prominent dynamic component was performed before and during graded sympathetic stimulation and catecholamine infusion. Phenoxybenzamine and propranolol were used to differentiate between α– and β–adrenoceptor effects. The study first confirmed previous findings of a β–adrenergic inhibitory component in the neural control of microvascular resistance which attenuated the a–adrenergic constriction. The results concerning the interaction between adrenergic and myogenic control mechanisms corroborated the conclusion that the sympathoadrenal system, via its β–adrenergic link, exerts effective inhibitory action on myogenic excitatory reactions. As regards the neural control, its –adrenergic component seemed to quite precisely compensate for the reinforcing effect on the myogenic constrictor response which results from increased vascular tone per se (in this case caused by a–adrenergic constriction), interpreted as a physical ‘gain’ effect inherent in the inverse fourth power relationship between radius and resistance. The latter complicating factor, which implies non–linearity in integrated peripheral resistance control, was thus revealed only after β–blockade, but not on the vascular bed with intact adrenoceptors, where a given transmural pressure stimulus evoked an almost equally large myogenic constrictor response irrespective of the prevailing level of vascular tone. The β–inhibitory action of blood–borne noradrenaline was similar to the neural one, whereas that of adrenaline was more effective, causing decline of myogenic reactivity below control.
Effect of sensitization on spontaneous and phosphatidylserine–induced histamine release and on cyclic AMP and GMP levels in isolated rat mast cells
Authors: SYDBOM A. , FREDHOLM B. B. , UVNAS B.
Published: December 2008

Sprague Dawley rats were sensitized with 20/μg or 100 mg egg albumin (using pertussis vaccine as adjuvant). Mast cells isolated from the former group of animals showed a higher degree of histamine release upon challenge in vitro with egg albumin than those from the latter group. Using the lower amount of antigen for immunization mast cells from Hooded Lister rats showed an even higher degree of histamine release induced by antigen. An increased antigen–induced histamine release was associated with an increased spontaneous and phosphatidylserine–induced histamine release. Histamine release induced by phos–phatidylserine was found to be specific in so far as it was calcium dependent and theophyl–line–inhibited. The basal level of cyclic AMP in mast cells was significantly depressed by sensitization. There was a relationship between the cyclic AMP/cyclic GMP ratio and the degree of spontaneous, phosphatidylserine–induced and anaphylactic histamine release. The results suggest that sensitization induces an increased release of histamine not only to the specific antigenic stimulus but also to more unspecific stimuli. Concomitantly there is a fall in the cyclic AMP/cyclic GMP ratio. The relationship between these two phenomena is discussed.
Relationship between serum IgE levels and anaphylactic histamine release from isolated rat mast cells
Authors: SYDBOM A. , KARLSSON T.
Published: December 2008

Inbred Hooded Lister rats were immunized with egg albumin with B. pertussis vaccine used as an adjuvant. The serum levels of total IgE and IgE antibody (egg albumin specific) were determined by radioimmunoassay techniques before and after immunization. The basic level of total IgE in serum was 560 ± 110 ng/ml. After immunization a maximal peak at day 11 of 1940 ± 160 ng/ml was registered. Anti‐egg albumin IgE antibody showed a maximum around day 13 of 75 ± 11 units/ml. Pleural mast cells were isolated on Ficoll between day 14 and 20 after immunization. A significant negative correlation between the basic total IgE level and histamine release by antigen (egg albumin) was found and also a significant positive correlation of specific IgE antibody (determined at day 11) and histamine release. The correlation between IgE level and histamine release was slightly improved if instead the ratio of specific IgE antibody over total IgE was used.