bluuebunny/crossref_metadata_2025 huggingface dataset:
Local Reflex in Microcirculation in Human Cutaneous Tissue
Authors: Henriksen O. , Sejrsen P.
Published: December 2008

Blood flow in cutaneous tissue measured by the local133Xenon washout technique decreased about 35 per cent during venous stasis of 40 mmHg in three normal subjects. The response was unaffected by block of the nerve three cm proximally to the labelled area. When the tissue was infiltrated with lidocaine or with phentolamine, blood flow remained constant, indicating that the decrease in blood flow is due to an arteriolar vasoconstrictor response to increase in venous transmural pressure. Local venous stasis elicited a vasoconstrictor response in an adjoining area not affected by the stasis. The response was blocked by lidocaine applied to the side of stasis. In 2 chronically sympathectomized patients, the vasoconstrictor response was abolished in the denervated limbs hut present on the non‐operated side (1 patient with unilateral sympathectomy). The results indicate that the vasoconstrictor response to an increase in venous transmural pressure is due to a local nervous mechanism involving sympathetic adrenergic fibres, most likely a sympathetic axon reflex.
Formation and Action of Prostaglandin Endoperoxides in the Isolated Human Umbilical Artery
Authors: Tuvemo Torsten , Strandberg Kjell , Hamberg Mats , Samuelsson Bengt
Published: December 2008

The effects on the isolated human umbilical artery (HUA) of the recently isolated endoperoxide intermediates in prostaglandin (PG) biosynthesis, PGG2 and PGH2, were studied. Both endoperoxides were potent contractors of the artery strips, the threshold concentrations being 3 (1–4) ng/ml for PGG2 and 1 (1–2) ng/ml for PGH2, as compared with 200 (40–400) ng/ml for PGE2. The hemiacetal derivative of 8‐(1‐hydroxy‐3‐oxopropyl)‐9,12L‐dihydroxy‐5,10‐heptadecadienoic acid (thromboxane B2), a metabolite of PGG2, appeared in the bath medium indicating PG and thromboxane generation in the isolated HUA. The formation of thromboxane B2 was inhibited by indomethacin (8–40 μg/ml) and by eicosa‐5,8,11,14‐tetraynoic acid (ETA) (25 μg/ml). ETA also inhibited the contractile responses to both endoperoxides. The results support the view that local generation of PGs might be involved in the closure of the HUA at birth.
Inhibition by Acidosis of Adenosine 3‘,5’‐Cyclic Monophosphate Accumulation and Lipolysis in Isolated Rat Fat Cells1
Authors: Fredholm Bertil B. , Hjemdahl Paul
Published: December 2008

Lipolysis and cyclic AMP accumulation were studied in isolated rat fat cells at normal (7.4) and decreased (7.0, 6.6) pH. Acidosis inhibited lipolysis and cyclic AMP accumulation due to NA non‐competetively. Maximal lipolysis (3 μM NA) was inhibited by 25% at pH 7.0 and by 61 % at pH 6.6. Cyclic AMP accumulation 5 min after 3 μM NA was inhibited by 57% at pH 7.0 and by 83% at pH 6.6. Between 10 and 60 minutes of incubation NA‐stimulated lipolysis was linear at pH 7.4, whereas a progressively increasing inhibition was seen at lower pH. The FFA production was inhibited to the same degree as glycerol production by acidosis. The fraction of FFA associated with the cells was the same at all pHs. Thus, we have no evidence that acidosis inhibits lipolysis via accumulation of FFA intracellularly. NA‐induced accumulation of3H‐cAMP from3H‐ATP, endogenously formed by prelabelling the cells with3H‐adenine, was inhibited by acidosis both in the presence and absence of theophylline in the incubation medium (by 48 and 44% respectively at pH 7.0 and by 74 and 68 % at pH 6.6). Cyclic nucleotide phosphodiesterase in homogenates of fat cells was inhibited by decreasing the pH, whether measured at high or low substrate concentrations. Basal adenylyl cyclase activity in a cell membrane fraction from fat cells was affected to a minor degree, while NA‐stimulated activity was inhibited by decreased pH. The response to 3 μM NA at pH 6.6 was inhibited by 43% relative to control. The results show that acidosis inhibits NA‐induced cyclic AMP accumulation by interfering with the formation, rather than the inactivation of the nucleotide. Since NA‐induced lipolysis is a cyclic AMP‐mediated process it is suggested that at least part of the antilipolytic effect of acidosis is due to inhibition of cyclic AMP formation.
Cyclic AMP‐Dependent and Independent Inhibition of Lipolysis by Adenosine and Decreased pH
Authors: Hjemdahl Paul , Fredholm Bertil B.
Published: December 2008

NA‐stimulated lipolysis and cAMP formation in isolated rat fat cells is inhibited by acidosis. In the present report we have examined the quantitative relationship between lipolysis and cAMP formation at normal and reduced pH and the possible involvement of adenosine, an endogenous inhibitor of cAMP formation. Adenosine antagonized cAMP accumulation and to a considerably lower degree lipolysis, effects potentiated by acidosis. Theophylline, an antagonist of adenosine effects, stimulated lipolysis and cAMP‐accumulation, and potentiated responses to NA. Adenosine deaminase (ADA) had theophylline‐like effects. Acidosis inhibited lipolysis and cAMP accumulation induced by ADA and theophylline to a larger extent than those induced by NA. It is suggested that adenosine modulates fat cell cAMP production and may contribute to the antilipolytic effect of acidosis. There was a curvilinear relationship between cAMP elevation and glycerol production in fat cell suspensions, which was different at pH 7.4 and at pH 6.6. The amount of cAMP needed for half‐maximal activation of lipolysis increased from 1.3 (pH 7.4) to 3.1 pMol × 10‐5cells (pH 6.6). The maximal glycerol production was reduced from 1 300 to 900 nMol × 10‐5cells. The antilipolytic effect of acidosis is apparently due partly to an inhibition of cAMP formation and partly to inhibition of subsequent step(s) in the activation sequence.
Rubrospinal Effects on Ventral Spinocerebellar Tract Neurones
Authors: Baldissera F. , ten Bruggencate G.
Published: December 2008

Stimulation of the contralateral red nucleus evoked monosynaptic EPSPs in 14 of 82 ventral spinocerebellar tract neurones. In some of these cells the monosynaptic EPSP was followed by a disynaptic IPSP. The remaining cell population received di‐ or polysynaptic PSPs from the rubrospinal tract, either EPSPs or IPSPs or both. Convergence of the rubrospinal tract onto interneurones of the segmental pathways projecting to VSCT cells was demonstrated. Rubrospinal volleys facilitated disynaptic Ia IPSPs evoked in VSCT neurones from both flexors and extensors, as well as disynaptic Ib IPSPs. Facilitation of the Ia interneurones was disynaptic whereas facilitation of Ib interneurones was monosynaptic. Disynaptic rubrospinal EPSPs and IPSPs were facilitated by volleys in ipsi‐ as well as in contralateral cutaneous and high threshold muscle afferents. The complex pattern of projections from the rubrospinal tract onto VSCT neurones and the related reflex pathways gives further support to the hypothesis that these tract cells convey information on transmission through interneurones of the spinal segmental mechanisms.
Signal Characteristics of EMG at Different Levels of Muscle Tension
Authors: Komi Paavo V. , Viitasalo Jukka H. T.
Published: December 2008

Electromyographic activity of m. rectus femoris at submaximal and maximal voluntary contractions was quantified by conventional integration technique and also be a more “qualitative” procedure of automated motor unit averaging and frequency spectrum analysis. By relating the EMG parameters to produced muscle tension it was observed that the integrated EMG increased in a slightly nonlinear fashion with the increase in muscle force. The other EMG variables also showed clear changes as a function of muscle tension. The averaged motor unit potential (AMUP) and its specific parameters (number of spikes, amplitude, rise time and amplitude‐rise time ratio) showed such changes with muscle tension that they may be useful in estimation of the recruitment pattern of the different types of motor units.
Myocardial Blood Flow in the Diving Seal
Authors: Blix Arnoldus Schytte , Kjekshus John K. , Enge Ivar , Bergan Anstein
Published: December 2008

Grey seals exhibit a marked drop in heart rate, a slight decrease in ventricular contractility, and an essentially unchanged stroke volume upon diving. In the present study, we have demonstrated that the resulting drop in cardiac output is associated with a 90% reduction of coronary blood flow. Such reduction of myocardial blood flow takes place despite a significant increase in effective coronary driving pressure, and is indicative of a 800% increase in coronary vascular resistance. This means that the circulatory adjustments displayed by the diving seal (i.e. a reduction of the workload on the heart) are so effective that myocardial blood flow can be reduced to 10% of the pre‐dive value without loss of cardiac function and blood pressure. It is suggested that even partial simulation of such a circulatory state might be a successful approach in the treatment of ischemic injuries in the heart of man.
The Nature of the Training Response; Peripheral and Central Adaptations to One‐Legged Exercise
Authors: Saltin B. , Nazar Kristina , Costill D. L. , Stein E. , Jansson Eva , Essén Birgitta , Gollnick P. D.
Published: December 2008

13 male subjects were studied and placed in 3 groups. Each group exercised one leg with sprint (S), or endurance (E) training and the other leg oppositely or not at all (NT). Oxygen uptake (Vo2), heart rate and blood lactate were measured for each leg separately and for both legs together during submaximal and maximal bicycle work before and after 4 weeks of training with 4–5 sessions per week. Muscle samples were obtained from the quadriceps muscle and assayed for succinate dehydrogenase (SDH) activity, and stained for myofibrillar AT Pase. In addition eight of the subjects performed after the training two‐legged exercise at 70% Vo2 max for one hour. The measurements included muscle glycogen and lactate concentrations of the two legs as well as the blood flow and the a‐v difference for O2, glucose and lactate.

The improvement in Vo2 max, the lowered heart rate and blood lactate response at submaximal work levels were only found when exercising with a trained leg (E or S). Part of the variables studied were markedly more changed with E as compared with S‐training. Although muscle fibre composition did not change a pronounced muscle adaptation took place with the training with enhancement of the SDH activity of the S and E legs while the NT‐leg did not change. Blood flow and oxygen uptake were similar in NT and S–E legs while femoral vein oxygen content was slightly lower in the trained as compared to the NT‐leg. Glycogen utilization was lowest in the trained leg with similar glucose uptake in all legs regardless of training status. Moreover, lactate was only continuously released from the NT‐leg. It is concluded that training induces marked local adaptations which not only affects the metabolic response to exercise but also are of importance eliciting an improved cardiovascular function.
Studies of Cerebral Osmoreceptors in Anesthetized Dogs: The Effect of Intravenous and Intracarotid Infusion of Hyper‐Osmolar Sodium Chloride Solutions during Sustained Water Diuresis
Authors: Bie Peter
Published: December 2008

The function of the suggested hypothalamic osmoreceptors was investigated in dogs during light chloralose anesthesia. The dogs were subjected to an i.v. load of 40 ml/kg b.wt. of a hypo‐osmolar solution of sodium chloride and glucose. This degree of hydration was kept constant by a specially constructed servo system based on the weight of the animal. During water diuresis the renal free water clearance remained essentially constant for several hours (mean about 0.2 ml/kg b.wt.‐min). Renal sodium excretion was low (mean 0.82 μmol/kg b.wt. · min) and decreased continuously throughout the experimental period. I.v. infusion of hyper‐osmolar sodium chloride solution (1.33 mmol/kg b.wt. in 30 min) was followed by prolonged parallel increases in free water clearance and sodium excretion, without any detectable change in the excretion of osmoles and potassium. The renal response to bilateral infusion of hyper‐osmolar NaCl (1.33 mmol/kg b.wt. in 30 min) into the common carotid arteries was identical to the response to i.v. infusion. The estimated increase in the osmolality of the carotid blood was 2.2 %. In seven out of eight experiments intracarotid infusion of NaCl (1.33 mmol/kg b.wt. in 8 min) did not elicit any reduction in free water clearance. On the contrary, an increase was found similar to that obtained after i.v. infusion. The estimated increase in the osmolality of the carotid blood was 8.4%. The present results question the validity of the currently held view that hypothalamic osmoreceptors play an important role in the control of the osmolality of plasma.
Convergence on Interneurones Mediating the Reciprocal Ia Inhibition of Motoneurones III. Effects from supraspinal pathways
Authors: Hultborn H. , Illert M. , Santini M.
Published: December 2008

Supraspinal effects were investigated in interneurones identified as mediating the disynaptic reciprocal Ia inhibition of motoneurones (referred to as “Ia inhibitory interneurones”). It was revealed that volleys in the vestibulospinal tract may evoke mono‐ and disynaptic EPSPs in interneurones monosynaptically excited from extensor muscles, i.e. extensor coupled Ia inhibitory interneurones. Flexor coupled interneurones instead received disynaptic inhibition. Volleys in the rubrospinal tract evoked a dominating polysynaptic excitation, usually mixed with inhibition, in flexor as well as extensor coupled interneurones. Disynaptic rubrospinal EPSPs and IPSPs were also revealed. The pyramidal tract also gives rise to a dominating polysynaptic excitation, usually mixed with inhibition, in flexor as well as extensor coupled Ia inhibitory interneurones. Rubrospinal and pyramidal volleys were shown to facilitate transmission in various segmental reflex pathways to the Ia inhibitory interneurones. A detailed comparison reveals a striking parallelism of segmental and supraspinal effects on α‐motoneurones and Ia inhibitory interneurones connected to the same muscles. This considerably strengthens the hypothesis of an “α–γ‐linkage in the reciprocal inhibition”.
Transfer of I125‐Albumin from Blood into Brain and Cerebrospinal Fluid in Newborn and Juvenile Rats
Authors: Amtorp Ole
Published: December 2008

Human fetuses, rabbit fetuses and newborn rats have a relatively high concentration of protein in cerebrospinal fluid (csf) as compared with the adult. The present study was undertaken in an attempt to evaluate whether this high protein concentration in newborn rats is caused by a high permeability of the blood‐brain‐csf barrier to protein or by a low production rate of csf. The results suggest that the high concentration of protein in csf in newborn rats is due to a low rate of production of csf rather than to an increased transfer of protein across the blood‐brain‐csf barrier.
Release of Adenosine‐like Material from Isolated Perfused Dog Adipose Tissue Following Sympathetic Nerve Stimulation and its Inhibition by Adrenergic α‐Receptor Blockade
Authors: Fredholm Bertil B.
Published: December 2008

Following the intraarterial infusion ofsH‐adenine to isolated perfused canine subcutaneous adipose tissue, its adenine nucleotides are labelled. A continuous release of radioactivity, comprised of non‐nucleotide material, was observed. The rate of this release was markedly enhanced by sympathetic nerve stimulation. The major components of the enhanced release appeared to be inosine and adenosine. Adrenergic α‐receptor blockade (phentolamine or Hydergin®) abolished the enhanced nucleoside release, while glycerol release was enhanced. The release of radioactivity was decreased during mechanical blood flow reduction and enhanced afterwards. However, the magnitude of this enhancement of release after clamp was much less than following nerve stimulation. The results suggest that adenosine or a closely related compound is released from canine subcutaneous adipose tissue by sympathetic nerve stimulation and that the release is related to adrenergic α‐receptor stimulation. Since adenosine is a potent inhibitor of catecholamine induced lipolysis in this tissue the possibility of a regulatory role must be considered.
Effects of Ultraviolet Radiation on Pinocytosis inAmoeba proteus
Authors: Josefsson J.‐O. , Hansson S. E.
Published: December 2008

Ultraviolet (UV) irradiation (4000–10000 erg × mm‐2) decreased membrane potential and input resistance ofAmoeba proteusand induced formation of pinocytotic channels. Submaximal pinocytosis induced by UV light was additive to pinocytosis induced by K+or Na+and stimulated in the presence of EGTA. It was not inhibited by the presence of La+++or by pretreatment with dibucaine. In these respects and with respect to optimum pH and pCa, UV induced pinocytosis resembled potassium induced pinocytosis. Accumulation of K+in the amoeba membrane after a dose of radiation may explain the similarity between pinocytosis induced by UV light and potassium salts. Ca++present during the period of irradiation inhibited the effect of UV light. Instead Ca++applied after irradiation (1–20 mM) increased channel formation. This effect was stimulated by the presence of local anesthetic drugs. It is suggested that high doses of UV light may induce channel formation by releasing Ca++from the cell membrane into the cell (UV induced pinocytosis). Ca++may be released at the moment of absorption of UV light in the membrane as well as during the period of depolarization which follows irradiation. Low doses of UV light may permit extracellular Ca++to enter the cell and stimulate channel formation (calcium induced pinocytosis). Dithiotreitol (1 mM) applied after irradiation depressed both UV and calcium induced pinocytosis so these may be the result of the same structural change which involves the formation of disulphide bonds in the membrane.
Mechanical and Metabolic Effects of β‐Receptor Stimulators, the C‐Terminal Octapeptide of Cholecystokinin, and Prostaglandin E2on the Isolated, Depolarized Sphincter of Odd
Authors: Andersson K.‐E. , Andersson R. , Hedner P. , Persson C. G. A.
Published: December 2008

Similar to their actions on normally polarized, isolated sphincter of Oddi, the β‐receptor stimulators isoprenaline and terbutaline, and prostaglandin E2produced relaxation of the depolarized preparation. The relaxation was accompanied by an increase in the intracellular content of cyclic AMP. In contrast to its relaxing effect on normally polarized sphincter preparations, the C‐terminal octapeptide of cholecystokinin (C8‐CCK) contracted or had no effect on the depolarized sphincter. There was no change or a small decrease in the content of cyclic AMP in the muscle. It is suggested that the relaxing effects of β‐receptor stimulators and prostaglandin E2on isolated sphincter of Oddi, and the simultaneous increase in cyclic AMP‐content are mediated by processes independent of the electrical activity of the membrane. However, C8‐CCK mediated relaxation and increase in cyclic AMP is dependent on the membrane potential.
Effects of Gonadotrophins on the Cumulus Oophorus of Isolated Rat Graafian Follicles
Authors: Hillensjö Torbjörn , Dekel Nava , Ahrén Kurt
Published: December 2008

Graafian follicles were extirpated before the endogenous LH surge on the day prior to ovulation from PMS‐injected immature rats. They were incubated in chemically defined medium in presence or absence of gonadotrophins for 4–10 h. After incubation the oocyte‐cumulus complexes were recovered from the follicles and one group inspected by Nomarski interference contrast microscopy and one group was placed in saline containing hyaluronidase. In hormone‐free medium both the oocyte and the cumulus cells remained morphologically unchanged: a dictyate oocyte surrounded by a compact mass of cumulus cells. Hyaluronidase did not detach cells from the cumulus structure. However, in presence of LH or FSH morphological changes developed in both cell types: the oocyte resumed meiosis as revealed by germinal vesicle breakdown and polar body formation; the cumulus structure became dispersed and embedded in a viscous matrix. The individual cumulus cells displayed pseudopodia‐like processes of the cell surface. Treatment with hyaluronidase resulted in detachment of cells from the cumulus. The effects of LH described on the oocyte and cumulus cells were unimpaired in presence of cyanoketone or aminoglutethimide although these agents blocked the follicular relase of progesterone, estradiol and androstenedione as revealed by RIA. The results indicate that a close functional relationship exists between the two cell types of the cumulus oophorus, the oocyte and the cumulus granulosa cells. Both cell types are affected directly or indirectly by gonadotrophins and characteristical morphological changes develop synchronously in both cell types.
Pathways for Chloride and Sodium Transport across Toad Skin
Authors: Bruus K. , Kristensen P. , Larsen E. Hviid
Published: December 2008

The voltage dependencies of Na and CI fluxes were investigated in the isolated toad skin. With Cl‐Ringer's on both sides Cl outflux varied very little with clamping voltage. The same was true for the influx of Cl at depolarizing voltages (ψi ‐ ψo < 0 mV). whereas hyperpolarization led to a marked increase in this flux. A net chloride influx under short circuit conditions indicated active transport of chloride. The outflux of Cl was a saturable function of outside Cl concentration. The outflux of urea was hardly affected by raising outside Cl concentration, and the effect of varying outside nitrate concentration on Cl outflux was likewise small. Both influx and outflux could be inhibited partially by acetazolamide. The outflux of Na varied with the clamping voltage as would be expected for an ion transported by electrodiffusion, and it was shown that amiloride had no effect on Na outflux, so it was concluded that the Na outflux route is paracellular. In the absence of Cl in the outside solution a small outflux of Cl persists. Also this flux varied with the clamping voltage according to laws for electrodiffusion. The variation of the ratio of sodium outflux to chloride outflux with clamping voltage indicated free passive diffusion of both these ions under the conditions mentioned. A comparison of the outfluxes of Na and Cl in skins bathed with gluconate Ringer's outside showed that the outflux route of these two ions was cation selective (PNa/Pcl= 1.88). When the paracellular leak pathway of the skins was opened by exposing the outside to hyperosmolar urea solutions, the ratio of the transport numbers was found to be TNa/Tcl= 1.71. The roles of the two ions in determining the steady state current‐voltage relationships were compared. At hyperpolarizing voltages most or all of the clamping current was carried by an inward Cl flux. By depolarization sodium influx plays an increasing role with increasing depolarization. Under short circuit conditions active chloride transport was found to contribute to the short circuit current.
Prostaglandin‐mediated Inhibition of Noradrenaline Release: Its Resistance to Variations in Rate of Prostaglandin Synthesis
Authors: Wennmalm ÅKe , Junstad Marianne
Published: December 2008

Isolated rabbit hearts were perfused according to Langendorff. The bilateral sympathetic nerve supply to the organ was stimulated at intervals, and the overflow of noradrenaline and of prostaglandins of the E series in the effluent was assayed, using fluorimetric and bioassay methods, respectively. The synthesis of prostaglandins in the organ was stimulated, either by perfusing the heart at a low pO2, or by infusing nicotinic acid. Hypoxia increased the coronary flow, provided the prostaglandin synthesis was not inhibited, probably as a consequence of hypoxia stimulation of the endogenous formation of prostaglandins. The release of NA in response to nerve stimulation was, however, unaffected by hypoxia. Nicotinic acid also stimulated prostaglandin formation, doubling the overflow of the lipid in response to nerve stimulation. In this series, too, the release of NA induced by nerve stimulation was unaffected by stimulation of prostaglandin synthesis. It is concluded that local variations in the rate of prostaglandin synthesis are unable to change the degree to which the release of sympathetic neurotransmitter is inhibited. Furthermore, it is suggested that the prostaglandin synthesis in rabbit heart takes place in compartments, separated functionally or morphologically.
Identification of the Mucopolysaccharides in Catecholamine‐Containing Subcellular Particle Fractions from Various Rat, Cat and Ox Tissues
Authors: Blaschke E. , Bergqvist U. , Uvnäs B.
Published: December 2008

Subcellular fractions containing adrenergic vesicles were obtained from bovine adrenal medulla and splenic nerve, rat and cat heart, and rat spleen. The fractions were washed free from lipids, digested with papain and the mucopolysaccharides (MPSs) then precipitated from the supernatant with ethanolic potassium acetate. The MPSs were identified by several different methods—microelectrophoresis on cellulose acetate in various media, cellulose column chromatography using elution solvents of increasing ionic strength, and treatment with specific enzymes followed by electrophoresis or column chromatography. The MPS precipitate from all the sources investigated contained dermatan sulphate or a dermatan sulphate‐chon‐droitin sulphate hybrid. In addition, the precipitate from rat spleen was found to contain chondroitin sulphate. Heparan sulphate was found in the precipitates from rat heart and spleen and hyaluronic acid in that from bovine splenic nerve. The finding of sulphomucopolysaccharides in the adrenergic vesicles, probably in a complex with protein, raises the question of the functional significance of such complexes. They might, by analogy with the ion‐exchange function of the heparin‐protein complex in mast cell granules, play a role in the storage and release of the amines.
Effect of Physical Training on LDH Activity and LDH Isozyme Pattern in Human Skeletal Muscle
Authors: Sjödin B. , Thorstensson A. , Frith K. , Karlsson J.
Published: December 2008

Total lactate dehydrogenase (LDH) activity and LDH isozyme pattern were studied in muscle biopsies obtained from m. vastus lateralis after 1) “aerobic” training performed as interval and extreme distance running, respectively (3 subjects); and 2) “anaerobic” training for two months, carried out as repeated maximal bursts of approximately 1 min running (6 subjects). After the “anaerobic training” no changes in LDH properties could be detected, although running performance improved. The extreme distance running resulted in a decrease in total LDH activity and an increase in relative activity of the heart specific isozymes. A relationship was also shown between the relative activity of these isozymes and the training distance covered. The relatively more aerobic conditions prevailing during distance running as compared to “anaerobic training” were proposed to decrease muscle specific subunits and/or increase synthesis of heart specific subunits in both muscle fibre types. This suggestion was supported by isozyme analysis of lyophilized and dissected single muscle fibres.
Hemodynamic Consequences of Resistance Vessel Rarification and of Changes in Smooth Muscle Sensitivity
Authors: Hallbäck M. , Göthberg G. , Lundin S. , Ricksten S.‐E. , Folkow B.
Published: December 2008

Alterations in resistance vessel design in form of an increased wall/lumen ratio appears to markedly influence the resistance control in primary hypertension (Folkow et al. 1973). The raised resistance has also been suggested to be a consequence of a rarification of resistance vessels or/and to an increased vascular smooth muscle sensitivity. Thus two series of paired experiments were performed on matched normotensive rats, utilizing the responses of their hindquarter vascular beds during constant flow perfusion. In the first series, the precapillary resistance vessels section was first “rarified” by graded microplugging, thereby raising resistance at maximal dilatation about 50 per cent. Then the vascular responses to noradrenaline were studied to characterize the dose‐response or “resistance curves”. In the second series the vascular smooth muscle sensitivity to noradrenaline of one of the hindquarters was changed by infusion of phentolamine. The resistance responses were then recorded and the ensuing “resistance curves” compared. These changes of resistance vascular architecture and vascular smooth muscle sensitivity, respectively, led to mutually different characters of the “resistance curves”. Both of these differ, however, in virtually all important respects from those curves characterizing vascular beds of spontaneously or renal hypertensive rats.
Renal Cortical Blood Redistribution after Bumetanide Related to Heterogenicity of Cortical Prostaglandin Metabolism in Dogs
Authors: Olsen Uffe Bang , Ahnfelt‐Rønne Ian
Published: December 2008

Bumetanide is shown to increase renal blood flow and to augment the proportion of the cortical blood flow to middle cortex. This redistribution still takes place even when renal blood flow is maintained constant by renal artery clamping. Indomethacin pretreatment inhibits the increase of renal blood flow as well as the cortical blood redistribution. In vitro examinations of canine kidney tissue slices suggest that outer cortex and papilla are sites of prostaglandin synthesis. No differences in prostaglandin E degradation are observed within the cortex. This suggests a relative autonomy for prostaglandins in the outer cortex, whilst inner cortical areas are dependent on medullary/papillary prostaglandin E supply. The renal hemodynamic effect of bumetanide is therefore thought to be a result of a stimulation of mainly medullary/papillary prostaglandin synthesis.
Effects of Secretagogues on Oxygen Consumption, Aminopyrine Accumulation and Morphology in Isolated Gastric Glands
Authors: BERGLINDH Thomas , Helander Herbert F. , ÖBrink Karl Johan
Published: December 2008

A recently developed method to isolate gastric glands from the rabbit gastric mucosa (Berglindh and Öbrink 1976) was used to study the effects of some common gastric secretagogues. Three parameters were investigated: 1) Respiratory activity; 2) Intraglandular accumulation of the weak base aminopyrine; 3) Quantitative morphology of the parietal cells. The following substances were tested: Histamine, cAMP, db‐cAMP, aminophylline, carbachol and pentagastrin. The strongest effect was obtained with db‐cAMP which dose‐dependently stimulated the respiration up to 200%, increased the aminopyrine accumulation 80% and altered the parietal cell morphology from a typically resting to a typically stimulated state. cAMP also stimulated the respiration but was about 10 times less effective on a molar basis than the dibutyryl form. Histamine, like db‐cAMP, stimulated the respiration in a dose‐dependent manner and strongly increased the aminopyrine accumulation. The morphological changes Were, however, not of the same magnitude as after db‐cAMP. Aminophylline, tested only for respiratory activity, stimulated the oxygen consumption moderately. Carbachol induced a transient increase in both the oxygen consumption and in the aminopyrine accumulation with a peak value after approximately 15 minutes for both, but gave no significant morphological alterations. Pentagastrin, finally, was incapable of inducing changes in any of the three parameters. Aminopyrine was also found to accumulate approx. 50 times in unstimulated, morphologically resting glands. This seems to indicate that there might be acid sites already in resting glands.
Glycerol Transport in Human Red Cells
Authors: Carlsen Anders , Wieth Jens Otto
Published: December 2008

The kinetics of 14C‐glycerol exchange was studied in human red cells. Glycerol appeared to be transported by two mechanisms: (i) by facilitated diffusion with permeability depending on glycerol concentration, and (ii) by an unspecific pathway, presumably representing the diffusion of individual glycerol molecules through the membrane with permeability independent of glycerol concentration. The latter permeability was 8 times 10‐8 cm/s at 20°C, it was independent of pH, and had an activation energy of 25 kcal/mol. The facilitated transport of glycerol was completely inhibited by Cu++, and the activation energy was low, about 10 kcal/mol. The transport system was competitively inhibited by H+, reacting with at least three hydrogen ions. The chemical specificity of the transport system was remarkably low: 1,3 propandiol, a structural analogue, as well as dimethylsulfoxide (a hydrogen bonding molecule with no structural resemblance to glycerol), inhibited glycerol transport competitively. Steins “dimerizer hypothesis” was revised according to our findings. A kinetic scheme describing the reactions of a transport controlling site with glycerol is presented in the Appendix. It is demonstrated in the article that the scheme accounts for our experimental results.
A Study of the Relationship between the Electrocardiogram and Hemodynamics in the Fetal Lamb during Asphyxia
Authors: Rosén K. G. , Hökegård K. H. , Kjellmer I.
Published: December 2008

Progressive changes in the S‐T interval of the fetal ECG were studied in 22 lamb fetuses, acutely exteriorized and submitted to graded hypoxia. The ECG changes were studied in order to correlate them with cardiovascular function, as measured by heart rate, mean arterial pressure, end diastolic pressure and combined cardiac output, estimated by the thermodilution method, as well as with blood gases and acid‐base status. Close correlations were obtained between Pao., pH and base deficit and the severity of ECG changes, graded according to a scoring system. Alterations in the ECG pattern consistently preceeded signs of failing cardiovascular function. Our previous findings indicated that the hypoxic ECG changes could be regarded as a sign of myocardial glycolysis. Accordingly, similar progressive ECG changes could be induced by isoprenaline injections. It is concluded that progressive changes of the S‐T interval of the fetal ECG contains information about fetal hypoxic stress before signs of failing cardiovascular function are seen.
Influence of Age, Growth, Castration and Testosterone Treatment on the Noradrenaline Levels of the Ductus Deferens and the Auxiliary Male Reproductive Glands of the Rat
Authors: Sjöstrand Nils O. , Swedin Göran
Published: December 2008

The total amount of noradrenaline (NA) in the male accessories increases with normal growth of the organs and also with the age of the rat. The ductus deferens of the old rat has about twice as high NA concentration as that of the young rat. Castration of the prepuberal rat or the puberal rat leads to retardation or cessation, respectively, of the increase in NA amount of the male genital tract. Only in the old rat does castration produce a definite decrease in NA amount of the tract. Castration always raises the NA concentration of the sex accessories. Testosterone treatment of the puberal rat or the old rat produces minor or no increase, respectively, in total amount of NA of the male sex accessories. Testosterone treatment of old prepuberally castrated rats produces a marked increase in NA content of the male organs. It is concluded that androgens have no substancial direct effect on the adrenergic innervation per se, but affects the transmitter levels of the male organs indirectly through changes in number, size and relative proportion of the target cells of the adrenergic nervesi.e. the smooth muscle cells.
A Perfluorochemical Oxygen Carrier (Fluosol‐43) in a Synthetic Medium Used for Perfusion of Isolated Rat Liver
Authors: Nováková Vera , Birke G. , Plantin L.‐O. , Wretlind A.
Published: December 2008

An emulsion of perfluorotributylamine (Fluosol‐43) was used as substitute for the gas‐carrying function of erythrocytes in a synthetic medium for perfusion of isolated rat liver. The efficiency and effect of this synthetic gas‐carrier were evaluated from measurements of the concentrations of rat albumin, the unsaturated vitamin B.,‐binding capacity of small‐molecular‐size vitamin B12‐binding proteins (UBBC of SBP), urea nitrogen, glucose, sodium, potassium, alanine amino transferase (ALAT) in the medium, and the incorporation of 14C‐lysine into the circulating proteins. Secretion of bile, portal pressure, PO2, PCO2 and pH in the affluent and the effluent mediums were also measured. The results demonstrate that the oxygen‐carrying capacity of the medium and the metabolic functions of the liver were higher, and the liver damage less, when the medium included Fluosol‐43 than without it. The albumin synthesis and the secretion of bile were as high as has been reported for perfusions with erythrocytes. This indicates that the oxygen carried by the Fluosol‐43 was utilised by the liver, and that the metabolic functions were not adversely affected during 4 h of perfusion by the medium containing Fluosol‐43.
A Possible Vagal Adrenergic Release of Serotonin from Enterochromaffin Cells in the Cat
Authors: Ahlman H. , Lundberg J. , Dahlstrom A. , Kewenter J.
Published: December 2008

The intracellular concentrations of serotonin (5‐HT) in enterochromaffin cells (EC) in the cat small intestine have been studied by a cytofluorimetric method before and after long‐lasting efferent vagal nerve stimulation in the neck. Such stimulation induces a decrease of 5‐HT in EC of the gut as observed previously. Pretreatment with atropine could not block this decrease, suggesting a noncholinergic mechanism. Pre‐treatment with a β‐blocking agent, propranolol, or bilateral removal of the superior cervical ganglia could, however, block this 5‐HT decrease. Pretreatment with an α‐blocking agent, phenoxybenzamine, caused an increase in the 5‐HT content of EC both with and without nerve stimulation; the reason for this is obscure. The results indicate, that vagal nerve stimulation induces a neurogenic 5‐HT release from EC in the gut, and that adrenergic fibres, originating in the superior cervical ganglia, mediate this release probably via a β‐receptor mechanism. Whether or not an α‐receptor mechanism is also involved cannot be judged at present.
Intracerebroventsicular Glycerol: A Potent Inhibitor of ADH‐release and Thirst
Authors: Olsson K. , Larsson B. , Liljekvist E.
Published: December 2008

Olsson, K., B. Larsson and E. Liljekvist. Intracerebroventricular glycerol: A potent inhibitor of ADH‐release and thirst. Acta physiol. scand. 1976. 98. 470477.

Infusions of isotonic or hypertonic (0.3 or 0.5 M) glycerol into the lateral cerebral ventricle (60 min, 0.02 ml/min) of non‐hydrated goats invariably induced a conspicuous and sustained water diuresis. Corresponding infusions of 0.3 M glycero 1/0. 16 M NaCl were almost equally efficient in this respect. A more short‐lasting and less pronounced water diuresis was obtained in response to equivalent infusions of pure d‐glucose, and the response to 0.3 M glucose/0.16 M NaCl was variable. Intravenous injections of vaso‐pressin blocked the glucose‐induced diuresis, but only postponed the glycerol‐induced diuresis. Intracerebroventricular (IVT) infusions of 0.5 M glycerol caused a sustained, complete inhibition of the urge to drink in the 48 h dehydrated goat, whereas IVT glucose only attenuated dehydrative drinking. Twenty min after the infusions of glycerol the CSF [Na+] in the lateral ventricle was about 15% below normal. About 1056 reduction of CSF [Na+] was obtained 20 min after the IVT infusion of glycerol/NaCI. The corresponding infusion of pure d‐glucose reduced the CSF [Na+] by <5%. The glycerol and glycerol/ NaCl infusions caused a moderate reduction of renal Na+ + K+ excretion. The possibility is discussed that the observed effects of IVT glycerol is a manifestation of its efficiency to inhibit choroidal and/or juxtaventricular (Na+‐K+)‐ATPase activity.
Capillary Permeability in Cutaneous Tissue
Authors: Paaske William P.
Published: December 2008

Paaske, W. P.Capillary permeability in cutaneous tissue. Acta physiol. scand. 1976.98. 492–499.

Capillary permeability in cutaneous tissue was determined by the single injection, external counting method. A rabbit abdominal skin preparation was developed. After local vasodilatation, 5 μ1 (400 μCi)51Cr‐EDTA was administered intraarterially by a special bolus injection technique, and the response curve was recorded by external registration. The capillary diffusion capacity (the permeability‐surface area product) for51Cr‐EDTA amounted to 3.7 m1/100 g·min at a capillary extraction of 0.59 and a plasma flow of 4.8 m1/100 gemin. The permeability coefficient for51Cr‐EDTA in cutaneous tissue was calculated to 0.9.10‐5cm/s assuming a capillary surface area of 70 cm2/g.
Intrarenal Distribution of Blood Flow and Glomerular Filtration during Chronic Unilateral Ureteral Obstruction
Authors: Clausen G. , Hope A.
Published: December 2008

Paired hydronephrotic (HN) and hypertrophic (HT) rat kidneys were studied after 6 days with complete unilateral ureteral obstruction without exposing the kidneys. Total HN renal blood flow (RBF), estimated by total microsphere (MS) uptake and from local125I‐antipyrine (Ap) uptake, averaged about 3/sec (n=147) for the extensor digitorum communis muscle and 3.39±0.68 m/sec (n=142) for the femoral quadriceps muscle. 4 of control. HN kidney GFR was reduced to about 1/2 of control level as estimated from inulin clearance of HT kidney times the HN to HT ratio for mean single nephron filtration rate, determined by14C‐ferrocyanide. Whereas blood flow (Ap) was proportionately reduced in outer and inner cortex (OC and 1C), fractional flow to the outer medulla (OM) was doubled as compared to controls (p < 0.01). Filtration was well preserved in deep as compared to superficial glomeruli with a smaller deep nonfiltering fraction (p > 0.02). Thus the results oppose the current concept that HN is characterized by disproportionate circulatory damage to IC and OM with little or no filtration in deep nephrons. In HT kidneys average RBF (MS) and GFR rose by about 1/2. Whereas total blood flow (Ap) rose proportionately in OC and IC, it remained at control level in OM, indicating dissociation between the total RBF and GFR and the effective blood flow to the OM zone.
Differentiation of Vasoconstrictor Sensitivity Caused by Prostaglandin E in Peripheral Vascular Beds of the Rabbit
Authors: Wennmalm ÅKe
Published: December 2008

The increase in perfusion pressure in the rabbit ear, hindleg and mesentery caused by close intra‐arterial injection of noradrenaline (NA), and the contractile response to NA of the rabbit aortic strip were investigated with respect to their sensitivity to prostaglandin E1(PGE1) and to the prostaglandin synthesis inhibitor indomethacin. PGEj (100–200 ng) potentiated the increases in perfusion pressure caused by NA in the perfused hindleg and mesentery, and the contractile response to NA of the aortic strip by 25–80%, but inhibited the increase in perfusion pressure by NA in the perfused ear by 35–100%. Indomethacin (3–5 10‐5M) significantly decreased the pressor responses to NA in the hindleg (by 45%) and mesentery (by 55%). This inhibitory effect by indomethacin was completely reversed by PGE1. The responses to NA in the aortic strip and the perfused ear were unaffected by indomethacin. It is concluded that the process of vasoconstriction in the vascular beds of the rabbit displays qualitative differences concerning its sensitivity to added PGEj. Furthermore, the decreased pressor responses to NA observed in some of the rabbit vascular beds after indomethacin indicate that the sensitivity to NA in these tissues in fact is increased by endogenous prostaglandin‐like substances (PLS). The current results thus suggest that endogenous PLS may regulate, at a local level, the vasoconstrictor sensitivity in the rabbit systemic resistance vessels.
The Compliance Curve for the Flow Limiting Segments of the Airway
Authors: Pedersen Ole Find , Nielsen Tage Mors
Published: December 2008

Maximum effort flow‐static recoil curves were obtained in 5 healthy subjects breathing air, He/O2, and SF6/O2 mixtures. In 4 of them maximum effort flows corresponded to really maximal flows and their curves were transformed into compliance curves for the flow limiting segments of the airway and analyzed from the point of view of a previously presented lung model (Pedersen and Nielsen 1976). The results showed, that viscosity dependent pressure losses from the alveoli to the flow limiting segments were minimal for air and SF6/O2, but not for He/O2. When viscosity dependent pressure losses could be neglected, then expiration of gases of different densities gave almost identical compliance curves for the flow limiting segments. This supported the applicability of the model. The calculated compliance curves for the flow limiting segments were compared with data from the literature, and the findings indicated that flow limitation during expirations with just maximal flows throughout began in the extrapulmonary airways and moved upstream during the expiration.
Effects of Prostaglandins on the Isolated Human Bladder and Urethra
Authors: Andersson K.‐E. , Ek A. , Persson C. G. A.
Published: December 2008

The effects of prostaglandins F2α (PGF2α), E2 (PGE1) and E2 (PGE2) on the human lower urinary tract were studied in vitro in preparations obtained from patients undergoing total cystourethrectomy because of bladder malignancy. Tissue specimens were taken from different parts of the urethra, the urethrovesical junction, and the bladder. From these specimens, smooth muscle preparations were dissected and mounted in organ baths, that were filled with Krebs solution (37°C) and bubbled with carbogen. Isometric tension was recorded. Preparations from the bladder and all parts of the urethra were contracted by PGF2α. This effect was not affected by tetrodotoxin, phenoxybenzamine, or atropine; isoprenaline relaxed the PGF2α induced contractions. PGE1 and PGE2 both contracted strips from the bladder. However, urethral preparations contracted by PGF2α or noradrenaline were relaxed by these agents. This relaxing effect was at least as pronounced as that produced by isoprenaline; it was not affected by propranolol.
Brain Energy Metabolism in Angiotensin‐Induced Acute Hypertension in Rats
Authors: Johansson Barbro B. , Siesjö Bo K.
Published: December 2008

In order to study if rapid elevation of blood pressure is associated with cerebral ischemia, anesthetized (70% N2O) and artificially ventilated rats were subjected to angiolensin‐induced hypertension. After a 5 min hypertensive period, cerebral cortex tissue was frozen in situ for subsequent measurements of labile glycolytic metabolites, ammonia, and organic phosphates. The degree of hypertension induced, which gave evidence of blood–brain barrier damage in 7 of 8 rats, did not affect the tissue concentrations of labile metabolites. It is concluded that ischemia does not contribute to the barrier damage, nor is it likely to be the cause of the clinical symptoms that may occur in conscious rats in the same experimental model.