bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of intravenous infusion on heart rate, sympathetic and vagal efferentation and left atrial and aortic baroreceptor activity in dogs
Authors: HAKUMÄKI MARTTI O. K.
Published: December 2008

The influence of 42 i.v. infusions of saline on heart rate, sympathetic and vagal cardiac efferent activity and on the aortic baroreceptor and left atrial B‐type nerve impulse activity was studied in 32 morphine‐chloralose anesthetized dogs. The responses in heart rate were tachycardic in 31 infusions and bradycardic in 11 infusions. In tachycardia, sympathetic activity increased in a majority of the cases but also decreases and nonsignificant changes were observed. Vagal efferentation decreased in most of the cases but also nonsignificant changes or increases in activity occurred. Sympathetic efferentation mainly decreased in bradycardic responses while vagal efferentation diverged in different directions in its nerve activity rate. The ratio of sympathetic to vagal impulses significantly correlated to the heart rate in most of the cases in tachycardia but not in bradycardia. It is concluded that sympathetic and vagal cardiac efferentation plays a significant role in heart rate regulation in volume load‐induced tachycardia but in bradycardia only the changes in sympathetic cardiac efferentation are important in respect to heart rate changes. The aortic baroreceptor and left atrial B‐type receptor activity rate increased both in tachycardia and bradycardia. Changes in the activities of these receptors do not explain the different heart rate responses. It is supposed that bradycardic responses result from changes in cardiac contraction associated with some reflex mechanism suppressing the excitatory influence of the activity of atrial receptors on sympathetic cardiac efferentation.
Tryptophylglycine dipeptide in ACTH/MSH cells of the human hypophysis: its identification and studies on its antinociceptive effects in mice
Authors: PARTANEN SEPPO , KAAKKOLA SEPPO , KÄÄRIÄINEN ILPO
Published: December 2008

The ACTH/MSH cells of the pars distalis and pars intermedia of the mammalian hypophysis contain peptides with amino‐terminal tryptophan which exhibit a strong fluorescence after treatment with modified formaldehyde vapour methods and with glyoxylic acid in the tissue sections from freeze‐dried specimens. By homogenization of the hypophyses in ethanolic glyoxylic acid and subsequent heating the peptides can be converted to highly fluorescent β‐carboline derivatives; these can then be extracted with glacial acetic acid, separated by silica gel thin‐layer chromatography and identified in UV light. Amino‐terminal tryptophyl peptide from adult human hypophysis extracted and treated in this way gave the structurel‐tryptophylglycine after acid hydrolysis. This structure was subsequently confirmed by producing a fluorescent derivative from authenticl‐tryptophylglycine using the same reaction conditions as for the tissue homogenate. This derivative moved in the same way in thin‐layer chromatography as fluorescent amino‐terminal tryptophyl peptide extracted from human hypophysis. Thereafter a study was made of the antinociceptive effects of authenticl‐tryptophylglycine administered subcutaneously in mice both alone and together with morphine.l‐tryptophylglycine had no antinociceptive effects alone and neither did it change morphine antinociception. Also it had no apparent effects on the behaviour of mice. Thus, ACTH/MSH cells contain a dipeptide whose physiological function differs from the effects of ACTH, MSH and endorphins.
Comparison of effects of pentobarbital and ethanol on the neuronal activity in the posterior parietal association cortex
Authors: HYVÄRINEN J. , LAAKSO M. , ROINE R. , LEINONEN L.
Published: December 2008

The problem of this study was whether the effects produced by alcohol in the posterior parietal association cortex are specific to this drug or shared by other centrally acting depressant drugs such as barbiturates. The effect of graded doses of pentobarbital on multineuronal impulse activity was recorded with transdural microelectrode technique in 30 expts. in Brodmann's area 7 of five stump‐tailed monkeys (Macaca speciosa). The results were compared with those from 32 expts. performed with alcohol and published separately. The dosage of the two drugs was determined on the basis of the monkeys' sensori‐motor coordination which was assessed with a rating scale of reaching accuracy for food rewards. There were several recording sites where the actions of the two drugs were similar at similar behavioural levels of intoxication. However, in the distribution of effects among various functional types of recording sites a significant difference was found between pentobarbital and alcohol. Alcohol commonly diminished cellular activity related to motor behaviour (reaching, grasping) and only rarely responses to somesthetic stimuli, whereas the effects of pentobarbital were the opposite being most common on somatosensory responses and least common on activity related to motor behaviour. Also responses to visual stimuli were more sensitive to pentobarbital than to alcohol. The actions of pentobarbital and alcohol on responses evoked by sensory stimulation differed significantly (P < 0.01). We conclude that significant differences exist in the mechanisms of action of alcohol and barbiturate on the associative systems of the brain.
Increase in local cerebral blood flow induced by circulating adrenaline: involvement of blood‐brain barrier dysfunction
Authors: ABDUL‐RAHMAN ALI , DAHLGREN NILS , JOHANSSON BARBRO B. , SIESJÖ BO K.
Published: December 2008

The influence of intravenous infusion of adrenaline (8 μg · kg‐1· min‐1) upon local cerebral blood flow (CBF) in paralyzed and artificially ventilated rats was measured autoradio‐graphically with14C‐iodoantipyrine as the diffusible tracer. At this dose, adrenaline invariably increased local CBF even though blood pressure was close to normal at the time of the CBF measurement. In average, local CBF increased to 400% of control. In 6 of 9 animals the increase in flow was inhomogenous with randomingly distributed areas of very high flow rates. Experiments withi.v.administration of Evans blue prior to infusion of adrenaline showed that areas of Evans blue extravasation appeared in 3 of 4 animals. Although areas of extravasation often corresponded to areas of high flow rates the former were much more circumscribed. Furthermore, very high flow rates were found in areas showing no sign of blood‐brain barrier dysfunction. It is concluded that the increase in CBF was at least partly due to a pressure‐mediated passage of adrenaline across the blood‐brain barrier but that such a passage can occur in the absence of macroscopically visible extravasation of protein.
Inhibition of fast axonal transport and microtubule polymerization in vitro by colchicine and colchiceine
Authors: EDSTRÖM ANDERS , HANSON MATS , WALLIN MARGARETA , CEDERHOLM BO
Published: December 2008

The effects of colchicine and colchiceine on fast axonal transport in frog sciatic nerves were studied in vitro. Colchiceine inhibited the transport to about the same extent as colchicine. Preincubation at low temperature potentiated the inhibitory effect of either drug. The polymerization of purified brain tubulin was inhibited by colchiceine at 5–10 times higher concentrations than colchicine. The similarity of the effects obtained with colchicine and colchiceine indicates that both drugs arrest axonal transport by interfering with microtubule function. Colchicine and colchiceine did not affect the levels of high energy phosphates (ATP and CrP) in frog nerves indicating that a reduced energy supply was not responsible for the arrested transport.
Increased hepatic glycogen synthetase and decreased phosphorylase in trained rats
Authors: GALBO H. , SAUGMANN P. , RICHTER E. A.
Published: December 2008

Rats were either physically trained by a 12 wk swimming program or were freely eating or weight matched, sedentary controls. Trained rats had a higher relative liver weight and total hepatic glycogen synthetase (EC 2.4.1.11) activity and a lower phosphorylase (EC 2.4.1.1) activity than the other groups of rats. These changes may partly explain the demonstrated training‐induced increase in glucose tolerance. None of the findings could be ascribed to differences in food intake or body weight.
Tachycardia during egg‐hypothermia in incubating ptarmigan (Lagopus lagopus)
Authors: GABRIELSEN GEIR , STEEN JOHAN B.
Published: December 2008

Incubating birds regulate the egg temperature by varying their posture and the distance between eggs and brood patch. In the present study, we show that this homeostatic process is further assisted by varying the brood patch blood flow according to the temperature of the eggs. When female ptarmigan resume incubation of cooled eggs (e.g. after a period of foraging), they immediately develop pronounced tachycardia (4 times normal in wild, 2–3 times in captive birds). Tachycardia is maintained, although at decreasing intensity, until the eggs have obtained normal temperature. The eggs are heated 30 to 50% slower in females where tachycardia is inhibited by a β‐receptor blocking agent.
Pre‐and postjunctional beta‐adrenoceptor mediated effects on transmitter release and effector response in the isolated rat portal vein
Authors: DAHLÖF CARL , LJUNG BENGT , ABLAD BENGT
Published: December 2008

Pre‐and postjunctional control mechanisms of the portal vein of spontaneously hypertensive rats (SHR) were characterized. Emphasis was placed on the influence of the presynaptic beta‐adrenoceptor mediated mechanism for regulation of neuronal noradrenaline (NA) release (studied as tritium overflow) and its consequences for the contractile response under in vitro conditions. It was found that isoprenaline increased, whereasdl/‐propranolol decreased the release of neuronal NA during transmural nerve stimulation, while effector responses remained unaltered.d‐Propranolol and the beta‐1 selective adrenoceptor antagonist, metoprolol, did not affect these two variables. It is concluded that the presynaptic beta‐adrenoceptors in the rat portal vein are mainly of the beta‐2 type and mediate facilitation of neuronal transmitter release and that concomitant changes of the effector responses of this tissue are below the level of detection under the present experimental conditions.
The postnatal development of the inferior oblique muscle of the cat
Authors: HANSON JERKER , LENNERSTRAND GUNNAR , NICHOLS KIRSTIN C.
Published: December 2008

Transversal sections of the inferior oblique muscle from kittens of various ages and from adult cats were stained for myofibrillar ATP‐ase at Ph 9.4 and 4.35, succinic dehydrogenase (SDH) and fat. The same muscles had previously been submitted to studies of contractional and fatigue properties. With ATPase the fibers could be differentiated into types I, II and II C. The percentages of each fiber type remained approximately the same from birth onwards. In the inner, global layer of the muscle, type I fibers showed a linear increase in size, but types II and IIC fibers an accelerated growth after age 20 weeks. In the outer, orbital layer, where no type I fibers were seen, types II and IIC fibers showed the same growth pattern as in the global layer. The fiber content of SHD and fat was low at birth but increased after two weeks of age. Type I fibers were poor and type IIC fibers rich in SDH and fat. Type II fibers showed varying amounts of these substances. Provided that type 1 fibers are slow, type II fast and type II C intermediate in speed of contraction, like in other muscles, the findings on fiber growth and SDH content seem to support the idea that slow, fatigue resistant components in eye muscles reach maturity earlier than fast components.
Chemical methods for fractionation of odorants produced by char smolts and tentative suggestions for pheromone origins
Authors: SELSET ROLF
Published: December 2008

Chemical procedures for fractionation of fish material containing odorants are described. These methods were developed with the aim of retaining the odorous activity of the material. Some of these methods were used to fractionate the intestinal contents of 1½ year old smolts of a population of anadromous char (Salmo alpinus L.). The fractions were prepared, (a) for behavioural experiments to study possible attraction effects on mature char of the same population during the migration season, and (b) for testing in physiological experiments to elucidate the olfactory potency of the different fractions. The nature and origin of the attractive substances are discussed.
Electrical field stimulation of myometrial strips from non‐pregnant and pregnant guinea‐pigs
Authors: ELMÉR M. , ALM P. , THORBERT G.
Published: December 2008

Myometrial tissue strips from term pregnant and non‐pregnant guinea‐pigs were studied in vitro by electrical field stimulation, and the adrenoceptor sensitivity to exogenously applied noradrenaline was determined. The induced response was characterized by various sympatholytic and nerve blocking drugs. In previously contracted strips from non‐pregnant animals field stimulation provoked a relaxation, probably mediated via postganglionic adrenergic nerve terminals and myometrial β‐receptors. In strips from myometrial tissue surrounding fetuses, no response was seen after field stimulation. Relaxation induced by exogenous noradrenaline was more pronounced and provoked at lower concentrations in pregnant than in non‐pregnant tissue. However, in non‐fetus‐carrying uterine horns in unilateral pregnancies field stimulation still induced a relaxation, and the sensitivity to exogenous noradrenaline was less than in the contra‐lateral fetus‐carrying horn. The physiological findings were compared with the endogenous level of uterine noradrenaline transmitter and the presence of adrenergic nerves, demonstrated by the Falck‐Hillarp fluorescence technique. It is suggested that the altered effects at term pregnancy are due to a pregnancy induced postganglionic denervation of the adrenergic terminals in the fetus‐carrying uterine horn. This is accompanied by an increased postsynaptic adrenoceptor sensitivity to the transmitter in analogue with a denervation supersensitivity after adrenergic denervation. Functionally, the present results verify the recent structural and biochemical findings of an adrenergic nerve degeneration in fetus‐carrying myometrial tissue during pregnancy, probably representing a very special neuroendocrine neuron‐target relationship.
Alterations in membrane electrical properties during long‐term denervation of rat skeletal muscle
Authors: SELLIN LAWRENCE C. , THESLEFF STEPHEN
Published: December 2008

Some membrane electrical properties of the extensor digitorum longus muscle of the rat were examined up to 21 days after denervation. The resting potential was significantly more depolarized at 3 days after denervation than it was at later times. The rate of rise (dV/dt) of the action potential decreased throughout the time course of the study but approached a steady value between 14 and 21 days after denervation. In addition, the dV/dt of tetrodotoxin (TTX)‐resistant action potentials increased up to and including 7 days after nerve section, but declined thereafter. When expressed as % of control, the dose‐response to TTX was similar throughout denervation. It is suggested that the large depolarization observed early in denervation may be related to the turnover of membrane constituents occurring at this time. The results also suggest that denervation produces a reduction in the number of fast TTX‐sensitive Na+ channels with the appearance of a new population of slow TTX‐resistant channels. However, long term denervation results in a reduction in the density of both types of channels.
Release of gastrin and somatostatin into the gastric lumen of healthy subjects and patients with duodenal ulcer and achlorhydria
Authors: WISÉN O. , UVNÄS‐WALLENSTEN KERSTIN , EFENDIĆ SUAD , JOHANSSON CATJA
Published: December 2008

Gastrin and somatostatin were measured in alkaline gastric instillates in normal subjects, patients with duodenal ulcer disease in quiescent state and in patients with achlorhydria. Both peptides were released into the lumen. The gastrin‐somatostatin ratio (G/S) in healthy subjects was approximately three. Duodenal ulcer patients had significantly lower G/S ratio due to lower gastrin and higher somatostatin levels whereas in patients with achlorhydria, the G/S ratio did not differ from normal subjects.
Functional properties of neurones in the posterior part of area 7 in awake monkey
Authors: LEINONEN LEA
Published: December 2008

The posterolateral part of the parietal association cortex (area 7 of Brodmann) was investigated in three awake, behaving macaque monkeys using transdural microelectrode recording technique. Only one of the 114 cells isolated remained unidentified. Of the cells 79% responded to somesthetic (39%) or visual (23%) or both somesthetic and visual (17%) stimulation. The somesthetic receptive fields were large, covering, for instance, the whole arm or hand. Most receptive fields were on the upper extremities. Half of the somesthetically drivable cells had bilateral receptive fields. The visually drivable cells responded only to stimuli moving in a certain direction. The effective stimuli for most of the cells responding both to visual and somatosensory stimulation were: touching of the skin and visual stimuli moving towards the cutaneous receptive field. Of the cells 20% were active only during the monkey's own movements, most often during grasping and manipulation with fingers. The results indicate that the area studied is specialized in the control of hand movements, e.g. grasping, grooming and somesthetic recognition of the forms of objects.
Sodium nitroprusside induced cGMP accumulation in isolated frog skin epithelium. Effect on CAMP, hydroosmotic and natriferic response to antidiuretic hormone
Authors: JOHNSEN ANDERS H. , NIELSEN ROBERT
Published: December 2008

The cGMP content of isolated frog skin epithelia has been measured, and the basal level was found to be 14.3±1.7 fmol/mg dry weight. 0.1 mM sodium nitroprusside induced a 10‐fold increase in the cGNP level within 5 min after which it rose more slowly. The maximum increase in cGMP level was obtained with 1 mM sodium nitroprusside, giving a 20–50‐fold increase. 1 mM sodium nitroprusside per se had no effect on osmotic water flow or active sodium transport. On the other hand, the osmotic water flow response to arginine vasotocin was somewhat enhanced in skins which had been pretreated with 1 mM sodium nitroprusside; thus the water flow responses to 1 and 31 ng/ml arginine vasotocin were on the average 31 and 14% higher in skins exposed to sodium nitroprusside than in control skins. Sodium nitroprusside had no effect on the increment in sodium transport rate elicited by arginine vasotocin. Sodium nitroprusside alone increased the cAMP level slightly; the enhanced cAMP level, reached after 30 min incubation with 40 ng/ml arginine vasotocin, was 20 % higher in the presence of 1 mM sodium nitroprusside. In conclusion: cGMP has no effect on osmotic water flow nor on active sodium transport and is not involved in the regulation of sodium transport by antidiuretic hormone. However, cGMP (or sodium nitroprusside) has a moderate effect on the hormone‐stimulated osmotic water flow.
Diurnal fluctuation in striatal choline acetyltransferase activity and strain difference in brain protein content of the rat
Authors: NORDBERG AGNETA , WAHLSTRÖM GÖRAN
Published: December 2008

Choline acetyltransferase (CAT) activity was measured in two brain regions of rat at different times of the day. A diurnal fluctuation of the CAT activity was found in the striaturn with a high activity during the light period and a low activity during the dark period. In the hippocampus+cortex the CAT activity remained constant. A marked difference in the brain protein content was found between two strains of Sprague‐Dawley rats. This finding emphasizes the importance of expressing enzyme activity both per g tissue and g protein especially when comparing data between different research groups.
Mechanism of action of pentobarbital on the contractile system of isolated frog muscle fibres
Authors: KHAN A. RAUF
Published: December 2008

The effects of pentobarbital‐sodium were studied on single muscle fibres of frog skeletal muscle. In a concentration of 0.5 mM, pentobarbital potentiated the twitch response without significantly affecting the tetanus amplitude. The increase in twitch amplitude was accompanied by a marked increase in the rate of force development. The relaxation phase of both twitch and tetanus was prolonged. These mechanical changes were associated with an increased duration of the action potential. Pentobarbital also increased the amplitude and the rate of force development during the twitch after suppression by dantrolene. The S‐shaped curve relating peak contracture tension and log caffeine concentration was shifted to the left by pentobarbital. It is suggested that pentobarbital affects the contractile activity of the muscle fibre; (1) by increasing the rate of release of calcium from its storage sites, (2) by prolonging the duration of the action potential and (3) by inhibiting calcium resequestration by the sarcoplasmic reticulum (SR).
Topical application of penicillin into hippocampal in vitro slices: A methodological study using benzyl (14C) penicillin
Authors: OLOFSSON S. , RIDDERHEIM P.‐Å. , SILFVENIUS H.
Published: December 2008

A gas pressure system is employed for topical application of pico/nanolitre volumes of 9 mmol/1 benzyl (14C) penicillin into guinea‐pig in vitro transverse hippocampal slices. Control of pressure pulse parameters enables ejectates, computed after liquid scintillation, from 10 μm, 5 μm and 2 μm pipettes with high reliability of ejection. A detailed study was done on the ejection performance of 5 μm and 2 μm pipettes. It shows that for the 5 μm tips, with the chosen ejection parameters, feeding pressure=0.5 MPa, feeding pulse duration 50 ms, a 99% ejection incidence was obtained (n= 200). The mean volumes ejected were 0.12 and 0.5 nl (n= 50) for one and four pulses delivered respectively. The corresponding ejectate means obtained from five 2 μm pipettes given a feeding pressure of 1.5 MPa, and a feeding pulse duration of 70 ms, were 0.04 and 0.13 nl. Statistical evaluation of the individual pipette ejection performances gave characteristic regression slopes within each pipette group. A comparison between visually controlled injection into oil and injection into slice, showed a close correspondence. The applicability of the ejection method is discussed in relation to functional studies on the conversion of single neurones into “epileptic” ones.
Effect of vagotomy and glucose administration on gastric acid secretion in the Atlantic cod, Gadus morhua
Authors: HOLSTEIN B. , CEDERBERG C.
Published: December 2008

Cods were prepared for measurement of gastric acid secretion. Cannulae were implanted for drainage of the stomach and for separate perfusion of the stomach and intestine. Fishes, intestinally perfused with diluted sea‐water (33% SW) exhibited high rates of acid secretion. This “basal” secretion was abolished (96% inhibition) by bilateral vagotomy. Perfusion of the stomach with isosmotic glucose (5.5%) diminished the amount of titratable acid in the gastric effluence, and induced oral ingestion of water. Only part of the decrease could be explained by neutralization by ingested sea‐water. Perfusion of the intestine with 5.5% glucose, containing sea‐water to raise the osmolality to that of 50% SW, depressed gastric acid secretion compared to 50% SW‐perfused controls, without significantly affecting oral intake of water. I.m. administration of glucose, increasing plasma glucose to the same level as intraluminal administration, did not affect acid secretion or oral water ingestion. The study demonstrates the existence of a potential intestinal mechanism for inhibition of gastric acid secretion, and indicates that vagal activity is independent of the blood glucose level in the cod.
The ultrastructure of the gastric glands and its relation to induced secretory activity of cod, Gadus morhua (Day)
Authors: MATTISSON ARTUR , HOLSTEIN BJÖRN
Published: December 2008

Light and electron microscopic studies have been performed on different parts of cod stomach. The studies have been concentrated on the gastric glands of the gastric mucosa. The glands consist of only one cell type. This cell contains an apically located, comprehensive tubular system as well as zymogen granules and therefore probably secretes both acid and zymogen. The high degree of development of certain organelles and their mutual localization shows a structural organization which appears suitable for an effective secretion. What appears to be intermediate organelle forms are common. When acid secretion is increased by continuous intramuscular infusion of histamine or of carbachol the most marked structural changes are increases in the size of the gland lumen and in the cell membrane facing the lumen. Histamine in particular causes the appearance of numerous long and slender cell processes in an enlarged gland lumen. When the acid secretion, increased by histamine, had reached a plateau, metiamide was infused. This histamine H2‐receptor antagonist caused a decrease in acid secretion as well as in the size of the gland cell surface to values characteristic of untreated cod.
Effects of physical training on skeletal muscle metabolism and ultrastructure in 70 to 75‐year‐old men
Authors: ÖRLANDER JAN , ANIANSSON AMELIE
Published: December 2008

The effects of a 12‐week program of physical training on skeletal muscle (vastus lateralis) characteristics in 5 old men were investigated. Heart rates during submaximal bicycle exercise were decreased after training, indicating an improved cardiovascular function. As judged from enzyme activity measurements, the anaerobic capacity as well as the mitochondrial oxidative capacity were increased by the training. Fatty acid oxidation capacity remained unchanged, while the glycolytic potential tended to be increased, suggesting a somewhat different pattern of adaptation as compared to that seen in young subjects. Volume fractions of mitochondria and lipid droplets were unchanged with training, supporting the view that in old men, increases in oxidative capacity take place within the existing mitochondrial volume. It was concluded, that the aging human skeletal muscle remains trainable, and that the training response is similar, but possibly not identical, to that seen in younger age groups.
Catecholamine metabolism in neonatal rat brain during asphyxia and recovery
Authors: HEDNER THOMAS , LUNDBORG PER
Published: December 2008

Infant rats were subjected to various degrees of asphyxia — 1‐day‐old rats were exposed to 100% N2for 20 min and 4‐day‐old rats were exposed to 94%N2‐6%O2for 30 min. The activity of tyrosine hydroxylase, the first and rate limiting enzyme in the catecholamine (CA) synthesis, was studied in vivo in whole brain and in various brain parts by measuring the accumulation of dihydroxyphenylalanine (DOPA) after inhibition of aromatic L‐aminoacid decarboxylase with NSD 1015. Measurements of the endogenous levels of tyrosine, dopamine (DA) and noradrenaline (NA) were also made during asphyxia and recovery. During asphyxia there was a decrease in DOPA accumulation in the whole brain of the 1‐day‐old animals and in the striatum, midbrain and brainstem regions of the 4‐day‐old rats. In the recovery phase both tyrosine and DOPA levels in the whole brain of the 1‐day‐old animals increased approximately 2‐fold 30 min after anoxia. In the regional brain study, a significant increase compared to controls was only noted in the striatum region. After 2 h, tyrosine and DOPA accumulation had reached normal or subnormal levels. In the 1‐day‐old rats there were no changes in whole brain DA or NA levels during anoxia and recovery except for an increase in DA levels noted after 6 h in the recovery phase. The disappearance rate of DA but not NA during hypoxia was retarded in the whole brain of the 4‐day‐old animals after H 44/68 (α‐methyltyrosine), indicating a reduced nerve impulse activity in central dopaminergic but not noradrenergic nerves. The catecholamine neurotransmitters DA and NA are ascribed a lot of important functions in the mature brain. As hypoxia or anoxia cause profound changes in the metabolism of these transmitters during the neonatal period, this might be relevant as a factor underlying early childhood behavioural or neurological disorders.
Constant flow‐ vs. constant pressure‐perfusion for studies of pulmonary vasoactive responses
Authors: BJERTNÆS LARS , HAUGE ANTON
Published: December 2008

We have compared the pulmonary vascular responses to a standardized hypoxic vasoconstrictor stimulus (F1,0,2=0.02) obtained during 1) constant volume inflow, with pulmonary arterial pressure as the dependent variable, and 2) constant inflow pressure, with flow as the dependent variable. Isolated rat lungs were perfused at different baseline transvascular pressures. The experimental arrangement allowed changes between the two types of perfusion. Hypoxia at constant pressure perfusion gave a higher percentage rise in pulmonary vascular resistance (PVR) at all pressure levels. This advantage was however, more than offset by the finding that a) vascular closure (total or partial) often occurred, particularly below arterial pressure of 3 kPa, making detection of graded responses impossible, and b) the control situation was rarely regained. Responses obtained during constant flow were less reduced by elevations in baseline transvascular pressure, and the control situation was rapidly and completely regained. The observation that hypoxic vascular closure may occur in the pulmonary vascular bed supports the hypothesis that high altitude edema is caused by precapillary occlusion of a major part of the vascular bed, thereby subjecting still perfused regions to very high pressures and flow.
The effect of insulin on skeletal muscle contractions and its relation to the effect produced by β‐adrenoceptor stimulation
Authors: HOLMBERG EVA , WALDECK BERTIL
Published: December 2008

The soleus, a slow‐contracting, and the extensor digitorum longus (EDL), a fast‐contracting muscle, from the guinea‐pig were prepared for measurement of isometric contractions in vitro. Insulin, 2.5–55 mu/ml, caused a dose‐dependent depression of twitches and subtetanic concentrations of the soleus muscle similar to and additive with that produced by the β2‐adrenoceptor agonist, terbutaline. The effect of terbutaline but not that of insulin was blocked by propranolol. Insulin had no apparent effect on the contractions of the EDL, whereas terbutaline increased the force of contraction. When depressed by KC1, however, insulin partially restored the twitch tension in both muscles. The possible role of effects on the Na+‐K+transport is discussed.
Stimulation of HCO3‐ transport by gastric inhibitory peptide (GIP) in proximal duodenum of the bullfrog
Authors: FLEMSTRÖM GUNNAR , GARNER ANDREW
Published: December 2008

Proximal duodenum isolated from the bullfrog actively transports HCO3−, into the lumen, a process which is inhibited by acetazolamide and indomethacin and stimulated by prostaglandins (Flemström 1979, 1980a). Duodenal mucosa in this animal is devoid of Brunner glands, indicating that active HCO3− transport is a property of the surface epithelial cells. HCO3− is secreted by duodenal epithelium also in the dog in vivo and acetazolamide decreases the rate of loss of intraduodenally instilled acid in this species (Harmon, Woods & Gurll 1978). These results suggest that epithelial HCO3− transport contributes to duodenal disposal of luminal acid. The ability of gastric inhibitory peptide (GIP) to inhibit gastric emptying and acid secretion (Pearce, Polak & Bloom 1977) should decrease delivery of H+ions into the duodenum. The latter may be indicative of an ulceroprotective function and made it of interest to examine the effects of GIP on duodenal epithelial HCO3− transport.
Non‐autonomic component in bradycardia of endurance trained men at rest and during exercise
Authors: LEWIS STEVEN F. , NYLANDER EVA , GAD PRAM , ARESKOG NILS‐HOLGER
Published: December 2008

Autonomic nervous alterations have generally been held responsible for the bradycardia of the endurance athlete. In order to determine whether there is also a non‐autonomic component in the bradycardia of long‐term training, we compared the intrinsic heart rate (HR) of highly trained bicyclists (heart volume: 995±155 ml) with that of untrained men (heart volume: 805±195 ml) at rest and during bicycle ergometer exercise at 50, 75 and 100% of maximal oxygen uptake (VO2 max.) Intrinsic HR was achieved by combined vagal and beta‐adrenergic blockade with atropine and propranolol or metoprolol (cardioselective) injected intravenously. Intrinsic HR was significantly lower in trained (T) than in untrained (UT) at rest and at all levels of exercise. The chronotropic reserve from resting HR to maximal HR was identical in the two groups. Nearly identical intrinsic HRs were achieved with atropine and either beta‐adrenergic antagonist. HR differences between T and UT were very similar in magnitude—approximately 13 beats/min—at rest and during exercise at a given percentage of VO2 max, with and without autonomic blockade. Evidence is thus provided for a non‐autonomic component in the bradycardia of well‐trained men which may be responsible for a parallel downward shift in the relationship between HR and percentage of VO2 max. The lower intrinsic HR in well‐trained men might be explained by, i.a. the cardiac enlargement.
Intraglandular transport of 125I‐glandular kallikrein in the rat submandibular salivary gland
Authors: ØRSTAVIK TORILL B. , GAUTVIK K. M. , NUSTAD K.
Published: December 2008

The transport of radiolabeled rat submandibular gland kallikrein was studied after local administration to the resting and activated rat submandibular gland. The iodinated kallikrein was electrophoretically, immunologically, and biologically indistinguishable from the intact enzyme. After intraductal and intraglandular application the radioactivity in venous effluent was quantitated and characterized. As judged by gel‐filtration 125I‐kallikrein in venous effluent eluted at a position similar to that seen when the iodinated enzyme was mixed with plasma, but earlier than the elution of 125I‐kallikrein in buffer. In plasma, therefore, glandular kallikrein is probably bound to macromolecules. The radioactive fractions in venous effluent did not contain free iodine. Maximum concentration of 125I‐kallikrein in venous effluent of resting glands was repeatedly reached about 20 min after intraductal administration. Moreover, the ductal epithelium represented the main permeation barrier since after intraglandular application the maximum venous 125I‐kallikrein concentration was reached almost immediately. In activated gland (parasympathetic and sympathetic nerve stimulation), the venous 125I‐kallikrein concentration was inversely related to glandular blood flow. We conclude that kallikrein present in the duct lumen or in the interstitium is able to reach the circulation, thereby making possible the local generation of plasma‐kinins.
Skin blood flow in humans as a function of environmental temperature measured by ultrasound
Authors: THORESEN MARIANNE , WALLØE LARS
Published: December 2008

We have measured the blood velocities in arteries supplying the skin in humans both in areas with arteriovenous anastomoses (AVA) and in skin areas without AVA in different temperature situations by means of a pulsed, bidirectional doppler ultrasound instrument. The instrument measures the time average of the instantaneous mean of the blood velocities present in a cross‐section of a vessel. So long as the cross‐sectional area of the vessel is constant, this average velocity is proportional to volume flow. We observe rapid and large fluctuations in blood velocities in arteries supplying skin areas with AVA in a comfortably warm environment. These fluctuations are substantially larger and more rapid than described by previous authors who have used plethysmograph methods. The blood velocities are more constant both at higher and lower environmental temperatures. There are no similar fluctuations in blood velocity in arteries supplying skin areas without AVA.
Possible role of nerve impulse induced sodium ion flux in a proposed multivesicular fractional release of adrenaline and noradrenaline from the chromaffin cell
Authors: UVNÄS B. , ÅBORG C.‐H.
Published: December 2008

Based on own observations concerning a two‐compartment storage of CA in the adrenal medulla and a cation exchange dependent release of CA from perfused chromaffin granules in vitro, and encouraged by recent reports from other laboratories about the importance of sodium ions for the CA release from the adrenal gland, we propose a modification of the current quantal theory of CA secretion. Instead of secretion of quanta, each quantum corresponding to the content of one vesicle, we envisage a concomitant fractional release of CA from multiple vesicles adjacent to the chromaffin cell membrane. The CA secretion should be the result of a cation exchange across the contact area between the plasma membrane and the granule membrane during the period of depolarization caused by the nerve impulse. The size of the released quanta should be determined by the nerve impulse induced sodium ion flux and the number of such ions which reach the CA binding ionic sites in the cation exchanger pool (the release pool) of the granules.
Decreased release of somatostatin into the portal vein following electrical vagal stimulation in the cat
Authors: UVNÄS‐WALLENSTEN KERSTIN , EFENDIC SUAD , ROOVETE ARVED , JOHANSSON CATJA
Published: December 2008

Electrical vagal stimulations were performed in anesthetized cats, in which the spleen and the intestine below the duodenum had been removed. The cats were provided with acute antral pouches which were perfused during the experiments. Insulin, glucagon, gastrin and somatostatin were measured in portal vein blood (consisting of blood from the stomach and the pancreas). The antral perfusates were analyzed for gastrin and somatostatin. Electrical vagal stimulation increased the release of insulin and glucagon into the portal vein. Gastrin was elevated in antral perfusates and portal vein blood, whereas somatostatin increased in the antral perfusates, but was reduced in portal vein blood. We assume that antral somatostatin, like gastrin, is released into the blood. The finding that portal vein somatostatin was decreased following vagal stimulation, indicates that the release of somatostatin from another large source of somatostatin, presumably the fundic region of the stomach or the pancreas, was decreased by vagal activation.
Transcapillary exchange and distribution of carbon‐11 labelled ethanol in the isolated perfused rat liver
Authors: KEINÄNEN M. , KUIKKA J. , HESELIUS S.‐J. , SLJOLINNA E.‐M. , SOLIN O. , LÅNGSTRÖM B. , NÄNTÖ V.
Published: December 2008

The distribution kinetics of ethanol in the isolated perfused rat liver at various flow rates and ethanol concentrations were studied by the indicator diffusion technique using 11C‐labelled ethanol. A double tracer solution with 99mTc‐labelled red blood cells as the vascular reference and 11C‐ethanol as the test substance was injected into the catheter connected to the portal vein. Time‐activity curves were monitored by a Nal(T1) scintillation detector above the outflow catheter. The following values were obtained: 0.95±0.01 for the maximal extraction (Emax), 3.0±0. 1xflow (r=0.98) for the capillary permeability surface area product (PScap), 18.7±12.5% for the vascular volume (V1) and 56.2±9.0% for the ethanol distribution volume (V2). The volumes were calculated from the products of mean transit time (MTT) and flow (f), and PScap was calculated from the equation PScap=‐fxIn(l‐Emax). The results show that the ethanol distribution in the liver is flow limited since Emax, was constant at various flow rates (0.67–2.55 ml/gxmin‐1). The distribution volumes obtained agree well with the values for liver vascular volume and water distribution volume reported in the literature.
Effects of nine different gastrointestinal polypeptides on vascular smooth muscle in vitro
Authors: HELLSTRAND PER , JÄRHULT JOHANNES
Published: December 2008

Nine polypeptides of gastrointeatinal origin were tested for their possible effect on vascular smooth muscle of the rat portal vein. The substances tested were bornbesin. caerulein. glucagon, insulin, pentagastrin. secretin, somatostatin. substance P and vasoactive intestinal polypeptide (VIP). Cumulative dose‐response relations of integrated mechanical activity (mean tension) were obtained with maximal concentrations of the various peptides of 1–10 μg/ml. Within this concentration range, only substance P and VIP showed clearcut effects; substance P causing contraction and VIP relaxation. The dose of substance P needed to produce contraction was high (ED50>IμM) so that the physiological importance of this response is doubtful. On the other hand. ED50for the relaxing effect of VIP was about 15 nM, which is in accordance with concentrations reported to produce significant vasodilatation in vivo. The results support the view that vascular effects which have been reported to occur in response to the other 7 peptides are mainly of indirect origin and not mediated via direct action on vascular smooth muscle.
Juxtaglomerular cell activity during hemorrhage and ischemia as revealed by quinacrine histofluorescence
Authors: ÅLUND M.
Published: December 2008

Quinacrine (QC) binds with high affinity to the intracellular storage granules of juxtaglomerular cells (JG‐cells) in the afferent arteriolus of the glomerulus of the kidney. The present study tests whether QC bound to JG‐cells can be released. The cells were stimulated by renal ischemia and hemorrhagic shock combined with immobilization stress. 1 h after onset of renal ischemia QC‐JGI (modified Hartroft & Hartroft 1953) in 14C‐QC‐treated rats had decreased to about 40% in the ischemic kidney compared to a not ligated control kidney. The 14C‐contents in the ischemic kidney had decreased to 33% of that in the untouched control kidney. Hemorrhagic shock was obtained by bleeding into a reservoir for 15 min or 1 h. Rats who received QC or 14C‐QC 1 h before onset of bleeding showed no change in QC‐JGI (15 min shock) or 14C‐contents (1 h shock) as compared to controls. This was probably due to formation of new QC‐binding granules, which took up still circulating quinacrine thereby masking a release. If the time between the QC injection and the onset of shock was extended to about 15 h, when circulating amounts of QC are very low, a decrease of QC‐JGI (about 30% of controls) was seen in the kidneys of the shocked rats. The results are compatible with the possibility that QC in vivo bound to granules of JG‐cells could be released together with the content of the granules following stimuli known to induce renin release. Quinacrine‐binding therefore possibly provides a new method to study endocrine cells in the way it has been used in the present study as a marker of JG‐cell activity.
The effect of dibutyryl cyclic AMP and PGE2 on lysosomal enzyme release and lactate production in relation to bone resorption in vitro
Authors: LERNER ULF
Published: December 2008

The effect of dibutyryl cyclic AMP (dbcAMP) and PGE2 on the content and release of lysosomal and non‐lysosomal enzymes was studied in a bone organ culture system using half calvaria from 6–7–day‐old mice. In parallel the effect of dbcAMP and PGE2 on the release of calcium (Ca2+) and inorganic phosphate (P1), glucose consumption and lactate production was also followed. DbcAMP (2.5×10‐‐4 M) decreased the telease of β‐glucuronidase, β‐N‐acetyl‐glucosaminidase, acid phosphatase, Ca2+ and P1 during the first day of culture. During the 3rd and 4th day dbcAMP increased all these parameters. In contrast no changes in the release of lactate dehydrogenase (LDH) and alanine amino‐transferase (ALAT) were seen. Glucose consumption and lactate production was not stimulated by dbcAMP until the 3rd and 4th day. On the other hand, PGE2 (10‐‐7 M) stimulated the release of β‐glucuronidase, β‐N‐acetylglucosaminidase, Ca2+ and P1 as well as glucose consumption and lactate production already after 24 h and this stimulation was maintained throughout the culture period. No effect by PGE2 on the release of LDH and ALAT was registered. The activities of LDH in the bone explants after 96 h of culture were significantly augmented by both dbcAMP and PGE2. It is concluded that bone resorption stimulated by dbcAMP and PGE2, is associated with increased lysosomal enzyme release and lactate production.
Non‐ganglionic cholinergic excitatory pathways in the sympathetic supply to the feline stomach:An efferent system or afferents with excitatory axon collaterals?
Authors: DELBRO D. , LISANDER B.
Published: December 2008

Experiments were performed on chloralosed, adrenalectomized cats, paralysed with gal‐lamine and artificially ventilated. Gastric motility was recorded by the balloon method. Efferent stimulation of the cut greater splanchnic nerve, well proximal to the celiac ganglion, could either increase or decrease gastric tone. The excitatory responses called for higher stimulation intensities than the inhibitory ones but were as a rule observed at lower frequencies only (1–4 Hz). They could be abolished by atropine but were not prevented by bilateral vagotomy, hexamethonium nor guanethidine. The latter twodrugs rather reversed inhibitory responses to excitatory ones which exhibited a hyperbolic frequency‐response relationship with maximal effects already at 24 Hz. Heating of a nerve trunk selectively activates thin afferents of the delta group and C‐class. Heating of the greater splanchnic nerve caused an increase in gastric motility which, like that caused by electric stimulation, was not prevented by hexamethonium nor guanethidine; nor was it eliminated by cutting the nerve centrally, nor by vagotomy, while it was abolished by atropine. These results suggest that the excitatory gastric responses to efferent splanchnic nerve stimulation are due to antidromic activation of thin afferent fibres. Their functional significance remains obscure but their peripheral arborizations may convey ‘axon reflexes’ influencing gastrointestinal motility.
Convulsants (benzylpenic'illin and pentylenetetrazol) on potential clamped myelinated axons from the rat
Authors: BRISMAR T. , JEFFERYS J. G. R.
Published: December 2008

The effect of two convulsants, benzylpenicillin and pentylenetetrazol, was tested in potential clamp experiments on single rat myelinated nerve fibres. 10 mM concentrations did not affect the permeability properties of the nodal membrane. The convulsive action is therefore probably not mediated through changes in the excitability of central axons.