bluuebunny/crossref_metadata_2025 huggingface dataset:
Muscle glycogen depletion patterns in type I and subgroups of type II fibres during prolonged severe exercise in man
Authors: VØLLESTAD MINA KØPKE , VAAGE ODD , HERMANSEN LARS
Published: December 2008

Glycogen depletion of muscle fibre types I, IIA, IIAB and IIB was studied using a histochemical method to quantify glycogen content in individual fibres. The reliability was examined in 29 muscle biopsies, in which total glycogen content was compared to average periodic acid Schiff (PAS) stain intensity in sections from the same samples. Over a wide range of glycogen content (1–252 mmole glucosyl units. kg‐1 wet weight) a linear relationship (r=0.93) was found between the two methods for quantification of muscle glycogen. Glycogen depletion patterns in type I, IIA, IIAB and IIB fibres were studied in 5 subjects during exhaustive bicycle exercise at 75% of VO2 max. At rest before exercise glycogen content was 16% higher in type II subgroups than in type I (p<0.05).From start of exercise the same glycogen depletion rate was observed in type I and IIA.Glycogen content of Type IIAB and IIB was unchanged during the first part of exercise. Later a decrease was observed, first in type IIAB and finally in IIB, suggesting a decrease in threshold force of these fibre types. The results indicate physiological differences between the 3 subgroups of type II fibres in man, whereas at the present exercise intensity type I and IIA fibres were recruited simultaneously from start.
Different effects of cyclic nucleotide derivatives upon the rat oocyte‐cumulus complex in vitro
Authors: TÖRNELL JAN , BRÄNNSTRÖM MATS , HILLENSJÖ TORBJÖRN
Published: December 2008

The influence of cyclic nucleotides on meiosis in isolated rat oocytes was studied. It is known that dbcAMP inhibits the spontaneous maturation of isolated rat oocytes. However, the effect of other cyclic nucleotide derivatives upon meiosis has been poorly investigated. The present study shows that 8‐BrcAMP is comparatively ineffective in inhibiting oocyte meiosis but exerts a potent stimulatory effect on progesterone production in cumulus cells. Neither dbcGMP nor 8‐BrcGMP were able to inhibit the spontaneous maturation of cumulus‐enclosed oocytes. On the other hand, 8‐BrcGMP dose‐dependently inhibited the meiosis of denuded oocytes. This indicates that the cumulus cells may be of importance for a possible regulatory role of cGMP.These results show the differences in meiotic response to various cyclic nucleotide derivatives.
Vitamin E deficiency and the susceptibility to lipid peroxidation of mouse cardiac and skeletal muscles
Authors: SALMINEN A. , KAINULAINEN H. , ARSTILA A.U. , VIHKO V.
Published: December 2008

Effects of a short‐term vitamin E deficiency on some lipid peroxidative properties were investigated in mouse cardiac and skeletal muscles. The concentration of vitamin E decreased 35.8% in 5 weeks and 61.2% in 12 weeks in skeletal muscle. The corresponding decrease in cardiac muscle was 65.7% in 12 weeks. Simultaneously the susceptibility of muscle homogenates to in vitro lipid peroxidation increased with 48.6% (5 weeks) and 44.5% (12 weeks) in skeletal muscle and with 101.8% (12 weeks) in cardiac muscle. Highly significant negative correlations were observed between the concentration of vitamin E and in vitro lipid peroxidation in cardiac and skeletal muscles. Also the sensitivity to Fe2+‐induced peroxidation was increased in skeletal muscle after the deficiency of 5 weeks. The total contents of peroxidizable lipids (Fe2+‐induction) were significantly (approx.20%) decreased after 12 weeks in cardiac and skeletal muscles. The concentration of lipofuscin was unaffected in both muscles of vitamin E‐deficient mice. Vitamin E deficiency (5 weeks) decreased the activity of selenium‐dependent glutathione peroxidase in skeletal muscle but did not affect the activities of catalase and β‐glucuronidase and the concentrations of protein, reduced glutathione and total sulfhydryl groups. These results show that a short‐term vitamin E deficiency affects the peroxidative properties of cardiac and skeletal muscles and may thus expose the muscles to peroxidation injuries.
The effect of pressor doses of Angiotensin II on autoregulation and intrarenal distribution of glomerular filtration rate in the rat
Authors: GÖRANSSON ANN , SJÖQUIST MATS
Published: December 2008

This study was designed to investigate the effect of pressor doses of exogenous Angiotensin II (AII) on autoregulation and intrarenal distribution of single nephron glomerular filtration rate (SNGFR) in anesthetized, normotensive rats. SNGFR at all cortical levels of the left kidney was measured with a modified Hanssen technique at three renal arterial pressures (RAP): Spontaneous, 100±1 mmHg and 70±1 mmHg. In control rats, both outer cortical (OC) and inner cortical (IC) nephrons showed complete autoregulation of SNGFR when RAP was redced to 100±1 mmHg. Further reduction to 70±1 mmHg resulted in different responses among the cortical layers, accompanying a decrease in SNGFR.The SNGFRIc/SNGFRoc ratio increased from 1.36±0.053 to 1.52±0.047 and a fractional redistribution of glomerular filtration rate towards IC nephrons was seen. When the kidney was submitted to a RAP of 70±1 mmHg, there was a concomitant increase in central arterial pressure (CAP) from 120±4.3 to 134±3.2 mmHg. A continuous i. v.infusion of All (0.5 μg · min‐1· kg‐1 BW) increased mean arterial pressure from 123±1.4 to 142±3.8 mmHg, an effect corresponding to that on peripheral vascular resistance during reduction of RAP to 70±1 mmHg in control rats. This dose reduced SNGFR at all cortical levels, but did not per se lead to redistribution of SNGFR.A reduction in RAP to 100±1 mmHg during All administration resulted in impaired autoregulation of SNGFR in both OC and IC nephrons. Our results show that exogenous All impairs autoregulation and cannot per se have an effect mimicking the fractional redistribution seen in control rats with a reduction of RAP below the limit for autoregulation. However, in this situation intrarenally formed All may still be of importance for autoregulation and distribution of glomerular filtration rate.
Atropine‐sensitive gastric smooth muscle excitation by mucosal nociceptive stimulation—the involvement of an axon reflex?
Authors: DELBRO D. , LISANDER B. , ANDERSSON S.A.
Published: December 2008

Experiments were performed in chloralosed cats where gastric motility was recorded by the “volume method”.Mucosal and serosal nociceptive stimulations were accomplished by local heating to 45–52°C.Heating generally elicited gastric relaxatioins, mainly due to activation of extrinsic inhibitory reflexes, but mucosal heating sometimes caused contractile responses which were resistant to nicotinic and adrenergic blockade. The contractions were, however, blocked by atropine and, further, could not be demonstrated after degeneration of splanchnic aerents. On the basis of these and earlier results it is suggested that the gastric contractions induced by mucosal nociceptive stimulation are due to axon reflexes, conveyed by splanchnic afferents that, possibly via release of substance P, make non‐nicotinic reflex contacts with intramural excitatory cholinergic neurons.
Compliance of the interstitial space in rats
Authors: REED ROLF K. , WIIG HELGE
Published: December 2008

The contribution to the extracellular fluid volume (ECV) from plasma volume (PV) and the total interstitial volumes contained in skin (IFVS) and skeletal muscle (IFVM) has been studied in rats over a wide range of overhydration and dehydration. ECV was measured as the two‐hour distribution space for 51Cr‐EDTA after nephrectomy while PV was measured with radiolabelled albumin or erythrocytes. Total interstitial volumes in skin and skeletal muscle were calculated from measurement of local interstitial volumes and the amount of skin and skeletal muscle in the rat. In control conditions ECV was on average 24.12 ml/100 g body weight. PV was 11.0% of ECV in control while IFVS and IFVM was 28.1% and 19.0% respectively. In dehydration the change in PV was 13.3% of the change in ECV, while the change in IFVS and IFVM was 30.0% and 21.0% of the change in ECV respectively. In overhydration (ECV on average 33.76 ml/100 g rat) the changes in PV, IFVS and IFVM were 7.5%, 22.1% and 17.2% of the change in ECV respectively. The regression coefficients describing the change between ECV and IFVS and IFVM were not significantly different in overhydration and dehydration while the regression coefficient between ECV and PV in overhydration was significantly less than the regression coefficient in dehydration. Thus, the fraction of ECV contained in skin and skeletal muscle is similar over the range of hydration studied. The fraction of ECV located in plasma is similar in control and dehydration, while in overhydration less of ECV is localized in plasma. The observed distribution of ECV validates previous compliance measurements based on pressure measurements in skin together with measurements of total ECV. The present results support the hypothesis that regulation of the total extracellular volume can be accomplished through regulation of plasma volume alone without the need for volume receptors located in the interstitium.
Cyclophosphamide treatment of prediabetic Chinese hamsters
Authors: GISHIZKY M. L. , FRANKEL B. J. , GRODSKY G. M.
Published: December 2008

To assess the immune system's involvement in the causation of diabetes in the genetically diabetic Chinese hamster, “prediabetic” animals were immunosuppressed with Cyclophosphamide, starting several weeks prior to the expected onset of hyperglycemia. The immunosuppressant dose was titrated to maximally depress the lymphocyte count without significant deleterious effects on food consumption, body weight or granulocyte count. Immunosuppression did not prevent or postpone the development of hyperglycemia or glucosuria. This suggests that if there is an autoimmune component in the etiology of diabetes in the genetically diabetic Chinese hamster, it takes place earlier or is of a more specific nature than that investigated in the present study.
Effects of lesions and ganglioside GM1 treatment on striatal polyamine levels and nigral DA neurons. A role of putrescine in the neurotropic activity of gangliosides
Authors: AGNATI LUIGI F. , FUXE KJELL , ZINI ISABELLA , DAVALLI P. , CORTI A. , CALZA LAURA , TOFFANO GINO , ZOLI MICHELE , PICCININI GIORGIO , GOLDSTEIN MENEK
Published: December 2008

The effects of a partial hemitransection at the meso‐diencephalic level, with or without chronic ganglioside GM1 treatment, have been evaulated on striatal polyamine levels, 7, 14 and 21 days after lesion, as well as on the ability of the polyamine synthesis inhibitor alpha‐difluoromethylornithine (α‐DFMO) to modulate the protective effects of chronic ganglioside GM1 treatment against retrograde degeneration of the nigral dopamine (DA) nerve cell bodies (14 day time interval). The striatal polyamine levels were measured by high pressure liquid chromatography after dansylation of the polyamines. The nigral DA nerve cells were studied by means of tyrosine hydroxylase (TH) immunocyto‐chemistry using the indirect immunoperoxidase technique. Quantitation was performed by means of morphometrical evaluation of the TH immunoreactive area of the substantia nigra. Seven days after partial hemitransection there is a marked increase (above 350%) in striatal putrescine levels, which is not modulated by chronic GM1 treatment. This marked increase could, to a large extent, be counteracted by simultaneous treatment with α‐DFMO, which blocks mainly the synthesis of putrescine. Twenty‐one days after lesion chronic GM1 treatment could produce an increase in striatal putrescine levels on the intact side and also after this time‐interval prevent the reduction of striatal spermine levels. It was also found that simultaneous treatment with α‐DFMO prevents the development of the protective action of chronic ganglioside GM1 treatment against retrograde degeneration of the nigral DA neurons. These results suggest that polyamines, and especially putrescine, may have a role as trophic factors in the central nervous system following lesions, and that the ganglioside GM1 requires the permissive action of putrescine to exert its protective effects against retrograde degeneration of the nigral DA nerve cells.
Effects of a synthetic vasopressin analogue (desmopressin) in pregnant, lactating and anoestral goats
Authors: OLSSON K. , DAHLBORN K.
Published: December 2008

The effects of the long‐acting synthetic vasopressin analogue desmopressin (dose 2times2 μg day‐1 for two days) were investigated in pregnant, lactating and anoestral goats. Urine flow fell and urine osmolality increased in all experiments. However, pregnant goats continued to drink the same volumes of water each day with the result that the ratio of water intake/urine output increased markedly and the plasma osmolality fell. The results support the hypothesis that the regulation of water intake is changed during pregnancy and that pregnant goats have a lowered sensitivity to signals that normally inhibit water consumption. In lactating goats, milk secretion was not affected by desmopressin. The animals did not drink enough to compensate for the water losses in milk and urine, but more than was needed to cover the water losses in the urine. The plasma osmolality decreased slightly. It appears as if the mechanisms involved in the control of water balance are not sufficiently adapted to take water losses via the milk into account, if the animals are subjected to challenges. In anoestral animals, the water balance was maintained during desmopressin injections. The renal sodium excretion did not change, but the renal potassium excretion decreased in pregnant and lactating goats in response to desmopressin.
Sympathetic reflex‐induced vasoconstriction during renal venous stasis elicited from the capsule in the dog kidney
Authors: ABILDGAARD ULRIK , HENRIKSEN OLE , AMTORP OLE
Published: December 2008

The study was performed in order to determine the effect of venous pressure elevation induced by unilateral partial renal venous ligation upon total renal blood flow and filtration fraction in the dog kidney. An anaesthesia with no known inhibitory effect on sympathetically mediated vasoconstriction was used. During control conditions instantaneous increase in renal venous pressure to 60 mmHg induced a decrease in renal blood flow (66 ±4%) corresponding to an ipsilateral vasoconstriction which was completely abolished following (1) surgical denervation of the kidney, (2) local a‐receptor blockade of the kidney, and (3) application of lidocain on the kidney surface. The most striking feature during step increase in renal venous pressure to 40 mmHg was an increase in renal vascular conductance. Renal venous pressure elevation of more than 40 mmHg induced a vasoconstriction, but the vasoconstrictor response was less pronounced as compared with that observed during instantaneous increase in renal venous pressure to the same level. The results strongly suggest that venous stasis of more than 40 mmHg activates an adrenergic sympathetic vasoconstrictor reflex comprising the spinal cord. The reflex is probably elicited from stretch receptors located in the renal capsule. Changes in filtration fraction at venous stasis during the experimental conditions indicate that renal venous pressure elevation activates mechanisms other than neural ones accounting for the reduction in the filtration fraction.
Dependency of renal potassium excretion on Na, K‐ATPase transport rate
Authors: SEJERSTED OLE M. , MONCLAIR TOM , MATHISEN ØYSTEIN , HARTMANN ANDERS , KIIL FREDRIK
Published: December 2008

Potassium secretion may depend on the transport rate of Na, K‐ATPase in basolateral cell membranes of distal tubular cells. To examine this hypothesis experiments were performed in anaesthetized dogs during inhibition of proximal potassium reabsorption by acetazolamide or mannitol (fractional potassium excretion 1.2‐1.4) or additional stimulation of potassium secretion by ethacrynic acid (fractional potassium excretion 2.1). Ouabain in a dose which inhibits 70–80% of the Na, K‐ATPase activity reduced fractional potassium excretion to 0.8‐0.9 by an effect on distal tubular secretion since potassium transport in the proximal tubules was not affected. Ouabain‐sensitive potassium excretion varied in proportion to ouabain‐sensitive sodium reabsorption during variation in glomerular nitration rate, even at urinary sodium concentrations exceeding 80 mmol 1‐1. In experiments without ouabain, saline infusion raised potassium excretion and sodium reabsorption until maximal Na, K‐ATPase transport rate was reached, as judged from heat production measurements, but not during further increments in urine flow. After inhibition of Na, K‐ATPase activity by hypokalaemia, potassium excretion and cortical heat production remained constant over a wide range of urine flow and sodium excretion. We conclude that potassium secretion is dependent on intact Na, K‐ATPase activity and is stimulated by sodium delivery to the distal nephron until maximal transport rate of the enzyme is reached.
Vitamin D3 stimulates calcium‐45 uptake by isolated mouse islets in vitro
Authors: FRANKEL B. J. , SEHLIN J. , TÄLJEDAL I.‐B.
Published: December 2008

Islets isolated from ob/ob mice which had been fed a vitamin D‐deficient diet released significantly less insulin in response to glucose than did vitamin D‐replete islets but showed normal net 45Ca2+ uptake. To determine whether vitamin D3 has a direct effect on the pancreatic B cell, islets from ob/ob mice on a normal diet were exposed to vitamin D, in vitro for 1 week or only 3 h, and then glucose‐stimulated 45Ca2+ uptake and insulin release were measured. Exposure to 1 nM or 1 μM vitamin D3 for 1 week stimulated 45Ca2+ uptake in the presence of 3 mti, but not 20 mM glucose, and did not affect insulin release. Exposure to vitamin D3 for 3 h did not significantly increase net 45Ca2+ uptake although there was a tendency to such an effect (P= 0.10). In conclusion, vitamin D‐deficiency in vivo suppressed subsequent glucose‐stimulated insulin release in vitro and this effect may be due to a direct effect of the sterol (or one of its metabolites) on calcium handling by the B cell.
Seasonal changes in the relative importance of different avenues of heat loss in resting and running reindeer
Authors: JOHNSEN H. K. , ROGNMO A. , NILSSEN K. J. , BLIX A. S.
Published: December 2008

Exhaled air temperature (Te), respiratory frequency (f), and rectal temperature (Tb) were measured in two reindeer before, during and after running for 45 min at a constant speed of 9.2 km‐hr‐1 on a level treadmill at different ambient temperatures (Ta), in summer with fur insulation at a minimum and in winter with fur insulation at its prime. Before and immediately after the 45‐min running period, skin temperature (Tsk) and radiative surface temperature (Tr) were also measured. Te, Tsk and Tr decreased at rest with decreasing Ta both summer and winter. Tb was elevated during running except at low Ta in summer. During running Tsk, Te and f were higher in winter than in summer, while Tr was higher in summer than in winter. The changes in Tr and Tsk in response to running were more pronounced on the legs than on the trunk. It is suggested that in the running reindeer the body surface is an effective avenue of heat loss during summer, while heat dissipation by way of the respiratory tract attains increased importance in winter, when fur insulation is at its best.
Insulin potentiates cholecystokinin (CCK)‐induced secretion of pancreatic kallikrein
Authors: BERG TORILL , JOHANSEN LIV , BREKKE INGE B.
Published: December 2008

The effects of insulin on pancreatic kallikrein secretion were studied in streptozotocin diabetic rats and after acute administration of insulin to normal rats. Studies on total protein and amylase secretion were included for comparison. In diabetic rats, the concentration of amylase in pancreatic tissue as well as basal and CCK‐stimulated amylase exocrine secretion were significantly reduced. Insulin treatment restored pancreatic tissue concentration and exocrine release of amylase to normal. Insulin deficiency did not induce any change in the concentration of kallikrein or trypsin‐like activity in pancreatic tissue. However, basal kallikrein secretion was higher in diabetic rats than in controls. Insulin treatment of diabetic rats did not alter basal kallikrein secretion but potentiated CCK‐stimulation of kallikrein release. In normal rats, CCK induced an increase of pancreatic protein, amylase, and kallikrein secretion but not pancreatic juice flow. Additional administration of insulin potentiated the CCK‐induced secretory rate of pancreatic juice, protein, and kallikrein but not amylase. A 1.6 times higher concentration of kallikrein was found in the portal vein than in arterial blood, indicating an endocrine release of pancreatic kallikrein. No difference in the concentration of circulating kallikrein was observed between the control and the insulin‐treated group.
Distribution, number and size of different types of fibres in whole cross‐sections of female m tibialis anterior. An enzyme histochemical study
Authors: HENRIKSSON‐LARSÉN K.
Published: December 2008

The aim of the study was to determine the distribution, total number and size of different types of fibres in whole cross‐sections of female m tibialis anterior and to compare these data with previous results obtained from male skeletal muscles as well as with data on female muscles obtained by biopsy technique. The distribution of fibre types varied within the muscle cross‐sections, and the pattern was slightly different from that earlier described for male muscles (Henriksson‐Larsén et al. 1983). No difference in mean fibre type occurrence was found between the left and right muscles of the females. The type 2 fibres varied in size in different muscle regions and were usually largest at the deep surface of the muscle. Both the total number and size of the muscle fibres were smaller in the female muscles than in the corresponding male muscles (Henriksson‐Larsén et al. 1985a, b). This resulted in a 30–40% smaller value for the total muscle fibre area in the female muscles compared to the male muscles.
Reduced uptake of noradrenaline into storage vesicles from the pregnant uterus
Authors: FRIED G. , HAMMARSTRÖM M. , DAHLIN I.
Published: December 2008

A noradrenaline (NA) storage vesicle fraction was isolated from the uteri of virgin as well as pregnant guinea‐pigs. The uptake of 3H‐NA into respective vesicle fractions was compared. Total uptake of 3H‐NA in the presence of Mg2+ (2.5 mM) and ATP (2.5 mM) at 30oC after 20 min was 6.0 ±1.4 pmol mg‐1 in uterus fractions from virgin guinea‐pigs as compared to 1.87 ± 0.41 pmol mg‐1 in uterus fractions from pregnant animals. When desipramine (5 mM) was added in order to block neuronal uptake the corresponding figures were 4.75± 0.92 and 0.51 ±0.18 pmol‐mg‐1, respectively. Thus in the presence of desipramine (5 mM) uptake was reduced by 21.4% in fractions from virgin uteri but by 72.7 % in fractions from pregnant uteri. Reserpine (0.1 μM) inhibited uptake of 3H‐NA by 34% in fractions from virgin uteri and by 46% in fractions from pregnant uteri. Our results indicate a decreased amount of functional storage vesicles in uteri of guinea‐pigs at term pregnancy and are consistent with the proposed degeneration of adrenergic nerves during pregnancy.
Dexamethasone reduces fat‐induced release of neurotensin in the rat
Authors: THEODORSSON‐NORHEIM E. , ROSELL S. , Brattsand R.
Published: December 2008

The effect of glucocorticoids on the release of neurotensin (NT) was studied in the rat. Oleic acid (200 μl) was instilled into the duodenum of fasted rats given saline or 1 mg kg‐1 dexamethasone subcutaneously 16 h prior to the experiment. Neurotensin‐like immunoreactivity (p‐NTLI) was analysed in unextracted plasma with the C‐terminal directed NT antiserum 6–8206. Pretreatment with dexamethasone almost totally abolished the fat‐induced increase in p‐NTLI. The data suggest that glucocorticoids may modulate the post‐prandial release of NT. Since NT is known to constrict the vascular beds of subcutaneous adipose tissue, this effect of glucocorticoids may be one of the factors responsible for the abnormal distribution of fat caused by high levels of glucocorticoids, e.g. in Cushing's syndrome.
An in vivo model for the simultaneous study of motility of the gallbladder, sphincter of Oddi and duodenal wall in the cat
Authors: DAHLSTRAND C. , EDIN R. , DAHLSTROM A. , AHLMAN H.
Published: December 2008

An in vivo model for the simultaneous study of motility of the gallbladder, sphincter of Oddi and the duodenal wall in species with an intraduodenal location of the sphincter has been developed. Gallbladder motility is registered by manometry, while transsphincteric flow and duodenal wall motility are recorded by perfusion methods. The sphincter of Oddi proper is totally uninfluenced by any mechanical procedures since the outflow of fluid is collected via a funnel‐shaped human femoral vein graft fixed to the duodenal mucosa by tiny sutures peripheral to the sphincteric muscle. The motility of the duodenal wall influences the flow of saline through a small feline vein graft inserted across the duodenal wall. The method is described in detail as well as nerve stimulation experiments and some pharmacological tests (e.g. infusion of substance P) to demonstrate the usefulness of the method. With this method the physiology and pharmacology of this region can be investigated in species, which, like man, have an intraduodenal location of the sphincter of Oddi.
Measurement of local blood flow in acute myocardial infarction: loss of 15‐^m microspheres during the first hour
Authors: ANDERSEN KNUT S. , SKJÆRVEN ROLV , LEKVEN JON
Published: December 2008

Distribution of radiolabeled microspheres is widely utilized for determination of regional blood flow in experimental myocardial infarction studies. The purpose of this investigation was evaluation of the microsphere method during 1 h of regional ischaemia. Special attention was focused upon loss of preocclusion microspheres from ischaemic myocardium; mechanisms for loss and blood flow distribution in non‐ischaemic left ventricle. Microspheres (15 μm) were injected into the left atrium in nine pentobarbital anaesthetized cats prior to coronary artery occlusion and again after 1 h of occlusion. Preocclusion blood flow estimates were lower in ischaemic compared with non‐ischaemic myocardium (1.36 us. 1.62 cm3min‐1 g‐1, P = 0.002), corresponding to 16%apparent loss. In endocardial ischaemic tissue, development of oedema could account for the loss. In epicardial ischaemic tissue, oedema was not present and loss was therefore due to migration of microspheres. Epicardial loss increased in proportion to restoration of left ventricular contractility. There was no evidence for significant microsphere loss through lymphatic pathways. In non‐ischaemic left ventricular tissue, myocardial blood flow was evenly distributed from apex to base, and also between endocardial and epicardial layers. This study quantitates an important limitation to measurements of local blood flow in ischaemic myocardium by radiolabelled microspheres.
Effects of reserpine and isoproterenol on elemental distribution in submandibular gland of rat
Authors: MÜLLER R. M. , GRUNDIN T. G. , ROOMANS G. M.
Published: December 2008

The effects of a single dose of reserpine or isoproterenol on the acinar cells of rat submandibular gland were investigated by electron microscopy and X‐ray microanalysis. About 4 h after injection of reserpine, the cellular Ca concentration started to increase and at 24 h a level two to three times the control value was reached. The mucus content of the cells increased in parallel with the Ca concentrations. Isoproterenol stimulation depleted the acinar cells of their mucus. Resynthesis of mucus was visible at 8–12 h after injection. Changes in cellular Ca concentrations followed the mucus content of the cells. After 24 h both the mucus content and the Ca concentration were significantly increased over the control values. High‐resolution X‐ray microanalysis on thin cryosections showed that the calcium was accumulated in the mucus granules, both after reserpine and after isoproterenol administration. The newly synthesized mucus was also more calcium‐rich than the original mucus. The effect of a single isoproterenol stimulation on elemental content of rat submandibular gland acinar cells was not significantly different from that of chronic isoproterenol treatment. Chronic treatment with reserpine resulted in a higher cellular Na/K ratio than a single dose.
Evidence that the arterial baroreceptors influence muscle blood flow and not subcutaneous flow in man
Authors: SKAGEN K. , BONDE‐PETERSEN F. , HENRIKSENJ O.
Published: December 2008

Studies in man indicate that skeletal muscle blood flow is modulated via high pressure baroreceptors located in the carotid body. However, whether subcutaneous blood flow is influenced in this way remains controversial. Therefore, the aim of the present study was to determine whether subcutaneous as well as skeletal muscle blood flow was influenced by direct carotid body stimulation; this was done by means of neck suction. Six young healthy males were investigated. Subcutaneous and skeletal muscle blood flow in the forearm was measured by the local 133Xe washout technique. Neck suction of – 20 mmHg was applied through a tight helmet covering the head and neck. In the supine position heart rate increased about 10%, mean arterial pressure was unchanged, subcutaneous blood flow was unchanged, but skeletal muscle blood flow increased about 70%. Measurements were repeated during neck suction, –20 mmHg, and 45o head‐up tilt (which is known to decrease subcutaneous blood flow and skeletal muscle blood flow by increasing sympathetic vasoconstrictor activity). Heart rate increased by about 20%, mean arterial pressure was unchanged, subcutaneous blood flow was unchanged and skeletal muscle blood flow increased about 100%. These results indicate that skeletal muscle blood flow is modulated through carotid baroreceptors. Subcutaneous blood flow seems not to be influenced by high pressure baroreceptor modulation, although a vasoconstrictor response to head‐up tilt was demonstrated in this as well as other recent studies.
The effects of different vitamin D‐states on intestinal absorption of vitamin D3 and its metabolites in rats
Authors: LORENTZON RONNY , DANIELSSON ÅKE
Published: December 2008

Rats were kept on a diet deficient in vitamin D for 2 months and were then randomly assigned to one of three groups with different supplies of vitamin D for 9 days. At the end of this period [3H]‐cholecalciferol (5μCi) was administered intragastrically and the serum radioactivity was recorded after various periods of time. The animals were kept in metabolic cages and urine and faeces were collected. After 3 days the animals were killed and the liver, kidney and fat tissue were investigated for radioactivity. The radioactivity was separated into different fractions of vitamin D by means of chromatography. The animals with vitamin D deficiency displayed higher levels of serum radioactivity, which were to a great extent confined to the fractions of the more polar metabolites (25(OH)D3 and 1,25(OH)2D3). There was significantly less radioactivity in the 3‐day faecal collection from these animals. In general, there was a low urinary excretion of radioactivity. In the rats with sufficient vitamin D, most of the radioactivity remained as the parent substance and was also detected in increased amounts in the liver, kidney and fat tissue. The results suggest a discriminatory enterohepatic cycling of vitamin D and its more polar metabolites leading to an increased faecal loss of the pro‐hormone in animals with a vitamin D surplus. It is proposed that the selectively effective enterohepatic reabsorption of the different metabolites may serve as a protective mechanism when body stores of vitamin D are overloaded.
Seasonal changes in blood lipids, adrenaline, noradrenaline, glucose and insulin in Norwegian reindeer
Authors: LARSEN TERJE S. , LAGERCRANTZ HUGO , RIEMERSMA RUDOLPH A. , BLIX ARNOLDUS SCHYTTE
Published: December 2008

Plasma concentrations of free fatty acids (FFA), glycerol, adrenaline, noradrenaline, glucose and insulin, as well as serum concentrations of triacylglycerols, total cholesterol and high density lipoprotein (HDL)‐bound cholesterol, were measured at intervals during a 1‐year period in Norwegian reindeer. Free fatty acids and glycerol were high in January‐March, low in April‐July, and high again in August‐September. Glucose was low in November‐February and high but variable in March‐October. Triacylglycerols, total and HDL‐bound cholesterol were all low in November‐March, but increasing in April and reaching a peak in August‐September. Plasma noradrenaline and adrenaline did not change significantly throughout the year. Plasma insulin was low in October‐April, increasing significantly from June‐August/September. The seasonal changes in the serum concentrations of triacylglycerols, total and HDL‐bound cholesterol, as well as the plasma concentration of glucose, coincided with the seasonal changes in food intake. Free fatty acids and, to some extent, glycerol were, in contrast, inversely related to feed intake. It is suggested that insulin may play an important role in the long‐term regulation of fat mobilization, while the importance of catecholamines in this respect is questionable.
Effects of digitoxin and hypokalaemia on pancreatic NaHCO3 secretion and pancreatic Na, K‐ATPase activity
Authors: GROTMOL TOM , BUANES TROND , MATHISEN ØYSTEIN , SCHISTAD OLE , SEJERSTED OLE M. , RÆDER MORTEN G.
Published: December 2008

To study the role played by Na, K‐ATPase in the pancreatic secretion of NaHCO3, experiments were performed in 20 anaesthetized, secretin‐infused pigs (3.0 clinical units.kg b. wt.·h‐1). The relationship between pancreatic NaHCO3 secretion and arterial pH was obtained before and during Na, K‐ATPase inhibition by digitoxin and hypokalaemia. Na, K‐ATPase activity in pancreatic tissue homogenate averaged 5.45 (5.02–6.68) μmol Pi. mg. protein. h‐1. Retrograde injection of 0.5ml 1.4 times 10‐4 mol.l‐1 digitoxin into pancreatic ducts reduced pancreatic Na, K‐ATPase activity by 31(18–47)%, while intra‐arterial injection of 0.2 mg.kg b. wt‐1 digitoxin reduced pancreatic Na, K‐ATPase activity by 50(45–56)%. Digitoxin and hypokalaemia reduced the rate of pancreatic NaHCO3 and shifted the normal, proportional relationship between NaHCO3 secretion and arterial pH towards higher pH. Hypokalaemia reduced Na, K‐ATPase activity and NaHCO3 secretion in proportion. These effects indicate that Na, K‐ATPase helps to sustain the requisite electrochemical potential gradients for driving H+ ions, and hence HCO‐3 ions, out of secretory cells.
Blood velocities in the uterine artery in humans during labour
Authors: JANBU T. , KOSS K. S. , NESHEIM B.‐I. , WESCHE J.
Published: December 2008

Blood velocities in the uterine arteries were measured during labour in humans, by means of the pulsed ultrasound Doppler velocity meter (UNIDOP). The uterine arteries were approached through the abdominal wall at the lateral border of the uterus and through the lateral vaginal fornix. At a depth of 0.5‐1.5 cm from the lateral vaginal fornix there were three different arteries in each woman. One of these arteries had similar velocity spectra to the uterine artery as measured through the abdominal wall higher up along the uterus, and the velocities were in the same range. The mean velocities were high and the velocities in diastole were high compared to those in systole. During uterine contractions the velocities were reduced during diastole, reducing mean velocities by 20–40% as measured through the vagina and by 50–60% when measured higher up through the abdominal wall. A second artery, which we believe is a branch of the uterine artery traversing the myometrium, had lower mean velocities and a greater difference between systole and diastole. During contractions the velocities were reduced by 100%. A third artery, which we believe is the descending branch of the uterine artery, supplying the cervix and vagina, had the lowest mean velocities, with backflow during diastole. During contractions the velocities increased 100–140%.
Effects of prolonged food restriction on some aspects of lipid metabolism in Norwegian and Svalbard reindeer
Authors: LARSEN TERJE S. , NILSSON NILS Ö. , BLIX ARNOLDUS SCHYTTE
Published: December 2008

The high‐arctic Svalbard reindeer (SR) deposit great amounts of body fat in autumn for subsequent use during winter when food is often in short supply. Captive SR and, for comparative reasons, the sub‐arctic Norwegian reindeer (NR) were offered 15% of their ad libitum food intake during a 21‐day period in September/October and its effect on fat metabolism was investigated. Plasma free fatty acids (FFA), glycerol, glucose, insulin and urea as well as lipogenic and lipolytic activity of isolated adipocytes were determined. Levels of FFA and glycerol increased immediately when food intake was restricted, reaching the highest levels in SR. Plasma glucose was fairly constant in NR, but decreased in SR. Plasma insulin decreased in both species. Plasma urea increased steadily from day 5 in NR and from day 11 in SR, after a transient rise on day 1 in both. Lipogenic activity had vanished completely in both NR and SR adipocytes when tested after 13 days of food restriction, while lipolytic activity was initially increased, after which it decreased in adipocytes from both species. After 21 days of food restriction SR adipocytes exhibited another marked increase in lipolytic activity, while the fat deposits of NR at that time were too small to allow examination. Thus, reindeer do not differ from other species in their lipogenic responses, although they show some hitherto undescribed lipolytic responses to prolonged food restriction.
Loss of an intrinsic capacity for human sperm chromatin decondensation
Authors: BJÖRNDAHL LARS , KVIST ULRIK
Published: December 2008

Chromatin decondensation of human ejaculated spermatozoa was studied in vitro, at various points of time after ejaculation, by sperm exposure to the detergent sodium dodecyl sulphate (SDS) containing zinc chelating EDTA. Within 5 min after ejaculation EDTA revealed a capacity for decondensation in 90% of the spermatozoa. This sperm capacity decreased rapidly upon storage. The results support the concept that the capacity to decondense is a normal property of freshly ejaculated spermatozoa and that this property may be rapidly lost. The loss is most probably due to an inability of thiol groups to take part in a thiol‐disulphide exchange in the sperm chromatin. A loss of functional thiols may hinder a capacity for chromatin decondensation inherent to the spermatozoon. A loss of thiols due to oxidation, that is, surplus S‐S bridge formation, may also delay hypothetical extrinsic S‐S cleaving factors in the ooplasm. In either case, the complete and non‐delayed sperm chromatin decondensation in the ovum may be hindered. This may result in the abnormal embryonic development observed in ova fertilized with aged spermatozoa.
Dissociation between pancreatic islet blood flow and insulin release in the rat
Authors: JANSSON LEIF
Published: December 2008

The blood flow to the pancreatic islets was estimated with the aid of microspheres in fed or starved (72 h) rats. The total pancreatic blood flow (PBF) in fed animals was 0.55 ± 0.04 ml. min‐1 x g pancreas and in the starved animals 0.30 ± 0.04 ml. min‐1 x g pancreas (P <0.001), and the corresponding islet blood flow (IBF) 82.0 ± 12.4 and 50.5 ± 9.7/9.7 μl min‐1 x g pancreas respectively (P > 0.05). Intraperitoneal injection of 2 ml of a 30% glucose solution caused a marked increase in IBF in both fed (P < 0.05) and starved (P < 0.01) animals to approximately the same level. The circulating insulin concentration remained unaffected by glucose in the starved rats but increased (P < 0.001) in the fed rats, indicating that insulin release does not necessarily rise in parallel with an elevated IBF. Intraperitoneal injection of 2 ml of a 30% solution of mannoheptulose, an inhibitor of islet glucose metabolism, decreased the serum insulin concentrations although the serum glucose concentrations rose significantly in both fed (P < 0.001) and starved (P < 0.001) animals. This treatment, however, caused both IBF and PBF to increase significantly in both groups. The data support the view that islet blood flow is not necessarily related to the metabolic status of the islet cells or to the insulin release.
Effects of graded focal cold block in rostral areas of the medulla
Authors: BUDZIŃSKA KRYSTYNA , von EULER CURT , KAO FREDERICK F. , PANTALEO TITO , YAMAMOTO YUJI
Published: December 2008

Unilateral focal cold blocks (20°C) in structures located ventrolaterally in rostral medulla consistently caused apnoea or deep depression of inspiratory motor output. The inhibitory effect could be correlated with the cooling temperature. Apnoeic response occurred either with complete absence of any inspiratory activity or combined with low level tonic inspiratory motor activity (‘tonic apnoea’). The appearance of apnoea was CO2‐independent, whereas the tonic component of the latter increased with increasing levels of PCO2. The results suggest that the structures in the deep, ventro‐lateral aspect of rostral medulla, from which apnoea can be induced, correspond partly to the nucleus paragigantocellularis lateralis (nPGL) and the nucleus preolivaris. These structures appear to be relevant for the drive inputs necessary for respiratory rhythmogenesis. Unilateral focal cooling in the rostral medulla, including the ‘Bötzinger Complex’, caused increments in respiratory rate both in vagotomized and non‐vagotomized animals. The increase in respiratory rate in response to cooling in the region of the ‘Bötzinger Complex’ was combined with either an enhancement or some depression of respiratory motor output. This area in the rostral part of the ventral respiratory group (VRG) seems not to be crucial for respiratory rhythmogenesis, but to play a role in determining both the intensity and timing of the respiratory activity. All effects of unilateral cold block were bilaterally symmetrical.
Effects of gymnemic acid on the chorda tympani proper nerve responses to sweet, sour, salty and bitter taste stimuli in the chimpanzee
Authors: HELLEKANT G. , SEGERSTAD C. HÅRD AF , ROBERTS T. , VAN DER WEL H. , BROUWER J. N. , GLASER D. , HAYNES R. , EICHBERG J. W.
Published: December 2008

In man gymnemic acid is able to abolish the sweet taste. Also in man, the neural correlate of that effect is a disappearance of the response to sweet stimuli in the taste nerves, as indicated by the observations of Diamant et al. (1965). Although a variety of other mammals also show neural responses to sweet‐tasting compounds, the corresponding effect of gymnemic acid has not been demonstrated. This study presents chorda tympani proper nerve recordings from the chimpanzee before and after gymnemic acid. On the chimpanzee tongue, application of 2 ml gymnemic acid (3–10 mg·ml‐1 for 3–4 min) completely abolished the taste responses to 0.0035 M acesulfam‐K, 0.0018 M aspartame, 0.015 M D‐tryptophan, 0.02% monellin, and 0.02% thaumatin, reduced by 75% the response to 0.3 M sucrose, and by 50% that of 0.76 M xylitol. No decrease was recorded in the responses to 0.001 M quinine, 0.1 M NaCl, 0.02 and 0.04 M ascorbic acid, 0.02 and 0.04 M citric acid. The response to the sweeteners recovered with time and the recovery was complete or nearly complete after one and a half hours. It was also found that after application of 2 ml miraculin, 3 mg·ml‐1 for 3 min to the tongue the neural response to acids was about 1.5 times as large as before. Gymnemic acid applied before miraculin prevented this enhancement and gymnemic acid after miraculin depressed the enhancement by miraculin of the response to citric and ascorbic acid.
Acid‐base and electrolyte balance after exhausting exercise in endurance‐trained and sprint‐trained subjects
Authors: MEDBØ JON INGULF , SEJERSTED OLE M.
Published: December 2008

High ability to perform strenuous exercise of short duration is accompanied by a large lactate formation in the exercising muscles, but the disturbances in extracellular acid‐base and electrolyte balance might be attenuated compared to subjects with less ability to perform intense exercise. To study this, oxygen deficit, changes in arterial blood acid‐base status and plasma electrolytes were studied in six‐endurance trained (ET) and six sprint‐trained (ST) subjects who exercised on a treadmill at a speed which led to exhaustion within 1 min. During exercise the ET and ST subjects developed an oxygen deficit of 41 and 56 ml oxygen units kg‐1 respectively, whereas peak blood lactate concentration post exercise averaged 12.5 and 16.7 mmol l‐1. Blood pH followed lactate concentration closely, reaching nadir values of 7.175 and 7.065 for ET and ST subjects respectively. Respiratory compensation and changes in blood bicarbonate and standard base deficit (SBD) concentrations for a given lactate concentration were the same for the two groups, amounting to a change in PCO2 of 0.12 kPa, in bicarbonate concentration of 1.09 mmol l‐1and inSBDof 1.44 mmol l‐1mM‐1 change in blood lactate concentration. During exercise the increase in haematocrit, from to 43 to 45 % for the ET subjects and from 46 to 50% for the ST subjects, was accompanied by almost parallel relative changes in plasma chloride and sodium concentrations. Whereas haematocrit continued to increase post exercise and followed blood lactate concentration closely, plasma sodium and chloride concentrations decreased to pre‐exercise values within 9 min of recovery. The anion gap increased significantly more than blood lactate concentration. Thus, ST subjects were capable of accumulating more lactate in blood compared with ET subjects, but at the expense of a lower pH, since the buffer capacity seemed to be the same for the two groups. The acidosis, which was larger than could be accounted for by lactic acid, was associated with an inexplicably large anion gap.
Oxytocin infusions increase plasma levels of insulin and VIP but not of gastrin in conscious dogs
Authors: STOCK S. , UVNÄS‐MOBERG K.
Published: December 2008

In the present study, a radioimmunoassay for oxytocin determinations is presented. In addition, we investigated whether the elevation of insulin, VIP and gastrin levels demonstrated to occur in response to suckling in lactating dogs may be induced by released oxytocin. Therefore, oxytocin was infused i.v. into conscious dogs in amounts calculated to give rise to plasma levels observed during physiological circumstances. Plasma levels of oxytocin, insulin, VIP (vasoactive intestinal polypeptide) and gastrin were measured by radioimmunoassay. When oxytocin was infused at a rate of 0.22 and 2.2 nmol kg‐1 h‐1, plasma oxytocin levels rose to 176 ± 25 fmol ml‐1 and to 1490 ± 400 fmol ml‐1, respectively, 10 min after the infusions were started. Plasma insulin levels rose in response to oxytocin administered at a rate of 0.22 and 2.2 nmol kg‐1 h‐1. A peak was recorded within 5 min of oxytocin infusion, that is, before maximal oxytocin levels were recorded, and basal levels were reached within about 20 min. The VIP levels rose slightly following infusion of oxytocin at 0.22 nmol kg‐1 h_I, but a clear‐cut response that lasted for 60 min was observed following infusion of oxytocin at the highest dose. In contrast, gastrin levels were not influenced by the oxytocin infusions. Suckling in dogs is followed by rapidly occurring short‐lasting elevations of oxytocin levels in plasma which amount to 50–100 fmol ml‐1. Since insulin and VIP were released by oxytocin when administered in amounts that give rise to plasma levels close to those levels, it is suggested that the secretion of insulin and VIP that occurs in response to suckling in lactating dogs may in part be caused by previously released oxytocin. If so, the role of oxytocin during lactation is not restricted to the contraction of the myoepithelial cells of the mammary glands but involves the control of neuroendocrine events associated with milk production and milk let‐down.