bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tension and cycb'c GMP changes in potassium depolarized rabbit colon muscle
Authors: Andersson Rolf G. G. , Djáurv Lars 
Published: December 2008

AbstractPotassium depolarization of rabbit colon muscle elicited a contraction consisting of 2 distinct phases, an initial rapid phasic contraction and a tonic contracture. The tonic contraction was, in contrast to the phasic contraction, dependent on the extracellular calcium for its development. There was a correlation between the tension development and the increase of the cyclic GMP level in the K+‐depolarized muscle. Experimental conditions which abolished the tonic contracture,vizglucose omission and treatment with Ca2+‐antagonists (verapamil, SKF 525A) also inhibited the cyclic GMP response. The changes of the cyclic GMP levels were Ca2+‐dependent. K+‐ions also changed the cyclic AMP content an effect which was atropine sensitive. From the experimental data obtained in this investigation we suggest that the co‐variation of the tension and the cyclic GMP level in the depolarized colon muscle might depend on oscillations in a common intracellular factor, probably Ca2+.
The effect of secretin on bile production, splanchnohepatic hemodynamics and liver function in cats
Authors: Larsen Jens Anker , Krarup Niels 
Published: December 2008

AbstractThe effect of secretin on bile flow, biliary clearance of 14C‐erythritol and bile composition was studied in fasting, chloralose anesthetized cats. Secretin (2 U · kg‐1·h‐1) increased bile flow by 85% and increased the rates of excretion of Na+, Cl‐ and HCO‐3. Bile flow increased from values below to values above the erythritol clearance, which did not change significantly. It is therefore concluded that secretin altered ductular transfer of fluid from a net reabsorption to a net secretion of a bicarbonate rich fluid. Secretin did not affect the sphlanchno‐hepatic hemodynamics or the overall function of the liver and Indomethacin did not significantly alter the response to secretin.
Sympathetic control of metabolic and hormonal responses to exercise in rats
Authors: Galbo H. , Richter E. A. , Christensen N. J. , Holst J. J. 
Published: December 2008

AbstractThe importance of the sympatho‐adrenal system for the pancreatic hormonal response to exercise and, furthermore, the role of glucagon and catecholamines for the hepatic glycogen depletion during exercise were studied. Rats were either surgically adrenomedullectomized and chemically sympathectomized with 6‐hydroxydopamine or shamtreated. Two weeks later the rats had either rabbit‐antiglucagon serum or normal rabbit serum injected. Subsequently the rats either rested or swam with a tail weight for 75 min. Immediately afterwards cardiac blood was drawn and liver and muscle tissue collected. In control rats in spite of an increase in blood glucose concentrations during exercise plasma insulin concentrations were unchanged, while glucagon concentrations increased. In sympathectomized rats, compared to control rats, glucagon concentrations increased less, and insulin concentrations were higher, although glucose concentrations were lower during exercise. Sympathectomy completely abolished the exercise‐induced decrease in liver and muscle glycogen concentrations, whereas neither glycogen depletion nor plasma catecholamine concentrations were influenced by the administration of glucagon antibodies. These findings indicate that the sympatho‐adrenal system enhances glucagon secretion as well as muscular and hepatic glycogen depletion but inhibits insulin secretion in exercising rats. The increase in glucagon concentrations, however, does not enhance hepatic glycogen depletion at the work load used.
Influence of indomethacin and of prostaglandin E1 on total and regional blood flow in man
Authors: Nowak Jacek , Wennmalm ÅRke 
Published: December 2008

AbstractThe central and regional circulatory effects in man of the prostaglandin synthetase inhibitor indomethacin and of prostaglandin E1 (PGE1) were studied. Systemic blood pressure, cardiac output, and renal and splanchnic blood flow were measured at rest, following infusion of indomethacin (50 mg i.v.), and during infusion of PGE1 (4–8 μg X min‐1 i.v.) after the administration of indomethacin. An increase in the total systemic resistance (+ 20%), as well as in the renal (+ 30%) and splanchnic (+ 16%) vascular resistances developed rapidly following the administration of indomethacin. Infusion of PGE1 completely restored the resistance in the renal and splanchnic regions, and in addition markedly increased the blood flow in non‐visceral tissues. We suggest that the circulatory effects by indomethacin are elicited via the drug's inhibitory effect on prostaglandin synthetase in the vessel walls, and that vasodilating products of PG synthetase affect the regional blood flow distribution in man.
Measurement of cerebral blood flow in the fetal lamb with a note on the flow‐distribution
Authors: Blomstrand Svante , Karlsson Kirsten , Kjellmer Ingemar 
Published: December 2008

AbstractThe cerebral blood flow was measured in the acutely exteriorized fetal lamb by 133Xenon washout and microsphere distribution techniques. The measurements were performed at different blood gas levels. Regional cerebral blood flow was calculated from the microsphere distribution for five different parts of the brain. This gave estimates for blood flow in both the grey and white matter of the hemispheres, which were in close agreement with the cerebral blood flow estimated by the 133Xe washout technique. The microsphere distribution shows that the fetal cerebral hemisphere has a low blood flow compared to the basal parts of the brain, and that this difference is increased during hypoxia and hypercarbia.
Histochemical and biochemical changes in human skeletal muscle with age in sedentary males, age 22–65 years
Authors: Larsson Lars , Sjödin Bertil , Karlsson Jan 
Published: December 2008

AbstractBiopsies for histochemical and biochemical analyses were taken from the vastus lateralis muscle of 55 untrained, healthy male subjects from 22 to 65 years of age. Fibre type distribution changed towards a decrease in the percentage of type II fibres, both in type IIA and type IIB fibres, whereas type IIB/IIA fibre ratio and type IIC percentage did not change with increasing age. It was found that the type IIB/flA fibre ratio was inversely related to type I fibres, i.e. subjects rich in type I fibres had a relatively smaller proportion of type IIB fibres. Fibre area determinations revealed a selective decrease in type II fibre area. Consequently, the type II/I fibre area ratio and relative type II fibre area decreased. No changes in the specific activities of Mg2+ stimulated ATPase and myokinase were observed, while the activity of lactate dehydrogenase (LDH) was higher in the youngest groups than in the oldest. LDH isozyme pattern shifted towards a decrease in percentage distribution of the muscle specific isozymes and a corresponding decrease in muscle specific activity while the activity of the heart specific isozymes did not change.
Isometric strength performance and muscle fibre type distribution in man
Authors: Tesch Per , Karlsson Jan 
Published: December 2008

AbstractMaximal isometric one‐leg strength (MIS) was determined in 31 physical education students displaying a wide range in muscle fibre type distribution (21–79% fast twitch (FT) muscle fibres) in their vastus lateralis muscles. A linear positive correlation was found between MIS and the relative distribution of FT fibres (p < 0.001). This should mean that not only muscle mass involved but also the quality of muscle will be decisive for the ability to develop high isometric strength.
Reinnervation of partially denervated rat soleus muscle
Authors: Thompson Wesley 
Published: December 2008

AbstractThe reinnervation of partially denervated rat soleus muscles by their interrupted, regenerating motor axons has been examined in adult white rats. If reinnervation occurred after the remaining, intact motor axons had sprouted to their full, maximal extent, then the regenerating axons formed synapses preferentially with denervated muscle fibers and not with fibers innervated by sprouts. The sprouted motor units retained their size as if no reinnervation had occurred. On the other hand, if reinnervation occurred early during the sprouting process, the sprouting motor units were never able to attain their maximal size. Further, some muscle fibers became innervated by both sprouted and regenerating axons. These “hyperinnervated” fibers lost their dual innervation within a few weeks. The sprouted axons seemed to be the nerve fibers preferentially eliminated from these hyperinnervated fibers, since during the loss of hyperinnervation the sprouted motor units decreased in size while the motor units formed by the regenerating axons did not change in size. It is proposed that the occurrence of hyperinnervation is influenced by the amount of time sprouting axons have to consolidate their synapses with muscle fibers. Further, it is proposed that on muscle fibers which can become hyperinnervated, the sprouted motor neurons are at a disadvantage in the competition for maintenance because of their larger unit sizes.
Delayed drinking in response to electrical and thermal stimulation of the medial forebrain
Authors: Rundgren Mats 
Published: December 2008

AbstractWater intake in response to electrical and thermal stimulation of the medial forebrain was studied in the goat. When the frontal wall of the third cerebral ventricle was included in a field of bipolar electrical stimulation a dipsogenic response was obtained after discontinuation of the stimulation. Release of antidiuretic hormone (ADH) was apparently also elicited. The water intake was roughly proportional to the amount of current which had been applied during the stimulation period. Water consumption in response to stimulation attenuated the dipsogenic effect of subsequent stimulation, as did also pre‐stimulatory hydration by stomach tube. A 2 C elevation of he temperature of parts of the preoptic/anterior hypothalamic region for 40 min periods induced cumulative drinking starting after 2.5 to 18 min. There were great interindividual differences in the amount of water consumed in response to the thermal stimulation, possibly due to variations in thermo‐couple electrode placement. The dipsogenic effect of forebrain warming was inhibited by pre‐hydration, and by lowering of the environmental temperature. The delayed thirst responses are discussed in relation to stimulus‐bound drinking previously observed in the same and other species. It appears possible that the delayed drinking was a manifestation of artificially induced excitation of juxtaventricular “thirst” receptors.
Effects of sodium salicylate on plasma insulin concentration and fatty acid turnover in dogs
Authors: Vik‐Mo By Harald , Hove Knut , Mjøs Ole D. 
Published: December 2008

AbstractThe effects of intravenous sodium salicylate administration on plasma concentrations of insulin, free fatty acids (FFA) and glucose were studied in intact, anaesthetized dogs both during basal and isoprenaline stimulated lipolysis. In both situations sodium salicylate reduced the plasma concentrations of insulin. The reduction was associated with decreased plasma FFA concentrations and FFA turnover rate, while plasma glucose concentrations remained unaltered. The reduced plasma insulin concentrations effected by sodium salicylate is most likely secondary to the concomitant fall in plasma FFA concentrations due to inhibition of FFA mobilization from adipose tissue.
Regional changes in structural and functional integrity of myometrial adrenergic nerves in pregnant guinea‐pig, and their relationship to the localization of the conceptus
Authors: Thorbert By G. , Alm P. , Owman Ch. , Sjöberg N.‐O. , Sporrong B. 
Published: December 2008

AbstractPregnancy is accompanied by a reduction in uterine noradrenaline, and the study was undertaken to investigate associated structural and functional integrity of the sympathetic nerves in the organ. The formaldehyde‐induced fluorescence of adrenergic nerves was studied in different uterine regions before and after in vitro incubation or injection with α‐methyl‐noradrenaline in pregnant and puerperal guinea‐pig uterus at 6 time periods, from early pregnancy (about 20 days post coitum) to 3 months post partum. The changes were related to the position of the fetuses, which were often present in only one of the two uterine horns. There was a drastic loss of fluorescent adrenergic nerves in myometrial tissue from horns distended by fetuses. Attemps to restore this fluorescence by incubation or injection with α‐methyl‐noradrenaline were essentially ineffective. Tissues from uterine regions outside (and not distended by) fetuses (in the case of early pregnancy), from horns devoid of fetuses (in the case of unilateral pregnancy), and from the cervix also lost their noradrenaline‐fluorescent nerves, but this occurred at a much later stage of pregnancy. After treatment with α‐methyl‐noradrenaline, a fluorescent plexus of sympathetic nerves could be restored to a considerable extent in these latter tissues. In puerperal animals the horn that had been devoid of fetuses regained its endogenous fluorescence much faster, and ihe uptake of α‐methyl‐noradrenaline was more efficient, than in the horn which had contained fetuses. In this latter horn clear signs of restoration of endogenous adrenergic fluorescence and a clear uptake capacity was not found until 3 months after delivery. In the tubal end of the uterus, the reduction in the number of fluorescent nerves was only insignificant, and the region thus clearly differed from the rest of the uterus. It is concluded that (1) there are clear regional differences with regard to the disappearance of the noradrenaline transmitter in the uterus, (2) this disappearance in early pregnancy is related to the position of the conceptus, and (3) the changes involve de‐and regenerative phenomena as well as alterations in transmitter levels of intact neurons.
The postnatal development of the inferior oblique muscle of the cat: I. Isometric twitch and tetanic properties
Authors: Lennerstrand Gunnar , Hanson Jerker 
Published: December 2008

AbstractThe postnatal development of the inferior oblique muscle in the cat has been studied with physiological and histochemical teckniques. This paper describes the changes with age in isometric twitch and tetanic response characteristics. The twitch amplitude increased and the twitch contraction time (ct) and half‐relaxation time (hrt) decreased almost linearly from birth to adulthood. The relation between the strength of nerve stimulation and twitch ct and hrt changed during development with a threshold slow response appearing at 10 weeks. Twitch responses in cats 6 weeks of age or older were of longer duration than in younger cats, in spite of the longer ct and hrt in young cats. Fusion frequency of the tetanic response reached a constant level in muscles 6 weeks or older. The maximum rate of tension rise remained the same from birth to 6 weeks of age and later increased markedly up to 20 weeks of age. The contracture induced by succinylcholine was the same in muscles of all ages. These data were related to previous findings on the postnatal development of fast and slow muscles and motor units in the hindlimb of the cat. A differentiation of the development of fast and slow eye muscle fibres is suggested. Slow fibres seemed to have completed their maturation at about ten weeks of age, while the development of fast fibre properties continued, probably up to the adult stage.
Maintenance of lactose secretion during acute insulin deficiency in lactating goats
Authors: Hove Knut 
Published: December 2008

AbstractInduction of alloxan diabetes in 5 lactating goats resulted in reduced milk yields in 3 of the animals, while the yield was unchanged in two. After treatment of the diabetic goats with insulin for 4–5 days–the last 24 h intravenously–lactose secretion returned to the control values before alloxan administration provided that normoglycemia developed. In 2 experiments infusion of a large dose of insulin caused hypoglycemia and a 20–30 per cent reduction in lactose secretion rates. In the course of 1 h after withdrawal of the insulin infusion, patent signs of insulin deficiency developed as evidenced by steadily increasing plasma glucose concentrations. Nevertheless, lactose secretion continued at the same rate as during insulin infusion for the 4 h studied after discontinuation of the insulin infusion. In the goats where lactose secretion was reduced due to insulin‐induced hypoglycemia, lactose secretion returned to control values when following discontinuation of insulin infusion the plasma glucose concentrations increased into normal and diabetic ranges. It is concluded that during insulin deficiency of short term duration, mammary lactose secretion was maintained at a normal rate. Since lactose is the major product of mammary glucose utilization, it is suggested that glucose uptake in the mammary gland was not reduced by short term insulin deficiency.
Morphology and contraction properties of cat lumbar back muscles
Authors: Carlson Hans 
Published: December 2008

AbstractThe gross morphology, innervation pattern and contraction properties of lumbar back muscles in the cat were investigated. The medially located multifidi and interspinales are formed by short bundles interconnecting adjacent vertebrae. Laterally located bundles composing longissimus and iliocostalis are attached to the spinous processes by a fascial layer and to the pelvic bone by a well developed intermuscular septum. Different spinal segments innervate the various sections along the muscles in such a way that the myotomes composing a muscle belly seem to be arranged after one another, in a row. The contraction time of a maximal isometric twitch is 34 ms for multifidi and interspinales and 29 ms for longissimus and iliocostalis. No large segmental variations of contraction times were found. The time course of twitch responses and a study of reflex contractions in middle and lower sections of lateral muscles indicate the presence also of a slowly contracting portion located to the longissimus. The initial muscle length is more decisive for the twitch amplitude of medial than of lateral muscles. In medial muscles summation of individual twitches starts at a stimulus frequency of 10–15 Hz and apparent fusion occurs at about 50 Hz. For lateral muscles corresponding values are 15–20 Hz and about 70 Hz. The contractile tension declines markedly in all muscles during a 10 min period of stimulation at 5 Hz.
Skeletal muscle fibre types, enzyme activities and physical performance in young males and females
Authors: Komi P. V. , Karlsson J. 
Published: December 2008

AbstractDifferences in skeletal muscle characteristics, metabolic profiles and functional performance between males and females were investigated using young (15–24 yrs) male and female twins as subjects. The comparison included such variables as anthropometry, muscle strength, mechanical power, maximum oxygen uptake, electrical activation of muscle, muscle fibre composition (m. vastus lateralis), and activities of several skeletal muscle enzymes. The results disclosed the following primary differences between males and females: In the various functional tests the performance of females was from 61.1 to 84.6% of that in males; distribution of slow twitch fibres in m. vastus lateralis of the females (49.1 ± 7.7%) was lower (p<.05) than that of the males (55.9 ± 11.9); activities of enzymes Ca2+ stimulated ATPase, CPK, phosphorylase and LDH ± were higher (p <.05‐.01) in the males, whereas the distribution pattern of LDH‐1 isozyme was higher (p <05) in the females. A pronounced difference between the two groups was an almost 100% longer rise time of isometric force in females. It is concluded that the males as compared to the females demonstrate higher aerobic and strength performance capacity, more efficient neuromotoric output during contraction, more slow twitch muscle fibres and more pronounced contractile and glycolytic profiles in the skeletal muscles.
Differentiation between pre‐ and postjunctional α‐receptors in guinea pig ileum and rabbit aorta
Authors: Wikberg Jarl 
Published: December 2008

AbstractElectric stimulation of proximal and terminal guinea pig ileum induced contractions which were mediated by stimulation of cholinergic neurons. After blocking β‐receptors, prejunctional α‐receptors mediating inhibition could be studied in these neurons. In proximal ileum the order of potencies of the following agonists was: clonidine (8)* < epinephrine (3) < oxymetazoline (2)< norepinephrine (1)< phenylephrine (0.02). The intrinsic activities of clonidine and phenylephrine were not maximal. In electrically stimulated terminal ileum practically identical results were obtained on the prejunctional α‐receptor except that phenylephrine was ineffective; the drug instead acted as a competitive blocker against norepinephrine. After blocking cholinergic receptors with atropine, excitatory α‐receptors located postjunctionally in the smooth muscle cells of terminal ileum could be studied. Under these conditions the order of potencies of the agonists was: oxymetazoline (40)< epinephrine (7) < phenylephrine (4)<norepinephrine (1)< clonidine (0.2). In contracting postjunctional α‐receptors in rabbit aorta the order of potencies was: oxymetazoline (5) < norepinephrine (1) < epinephrine (0.7) < phenylephrine (0.2) > clonidine (0.04). On the postjunctional α‐receptor in terminal guinea pig ileum phentolamine was 55 fold more effective in blocking the response of norepinephrine than it was on blocking the response on the prejunctional receptor of the same preparation. Phenoxybenzamine (4 times 10‐8M) was ineffective on the prejunctional α‐receptor of the cholinergic neuron, while it blocked the postjunctional α‐receptor of smooth muscle in guinea pig terminal ileum noncompetitively. It is suggested that the differences in the activities of clonidine and phenylephrine between prejunctional α‐receptors located to cholinergic neurons and postjunctional α‐receptors located to smooth muscle cells was due to a pharmacological difference between the receptors. The results obtained with the blockers support this suggestion.
Autoradiography on erythrokinesis and multihemoglobins in juvenile Salmo salar L. at various respiratory gas regimes
Authors: Härdig Jan , Olsson LarsÅke , Höglund Lars B. 
Published: December 2008

AbstractThe kinetics of erylhropoiesis in 5 6 month old Salmo salar L. was correlated to 4 combinations of environmental PO2 and pH/PCO2. Given single doses of 55Fe at the start of continuous flow bioassays, the incorporation was examined in circulating red blood cells (RBC) by autoradiography on blood smears. The proportions of immature, labelled immature and labelled mature erythrocytes were calculated on samples taken at intervals up to 52 days. Compared to control fish kept at a PO2 corresponding to 90% air saturation and pH PCO2 at 7.6/8 pH units/mmHg, oxygen depletion to 50% air saturation stimulated the proliferation of RBC stem cells and enhanced RBC maturation. Ceteris paribus, sustained hypercapnia at a PCO2 in the respiratory water raised to 23 mmHg (pH 7.1–7.2), stimulated proliferation but did not affect the output of mature RBC. Simultaneously lowered PO2 and raised PCO2 to the levels mentioned above obviously stressed the fish, as the effect of lowered PO2per se was not manifested. Radioactivity was traced to all clecdophorelically separable protein fractions from RBC hemolysates. The relevance of blood physiological criteria for probing the fitness or well being of fish in environmental respiratory stress conditions has been discussed.