Acta physiologica Scandinavica最新文献

{"title":"Relationship between decreased oxyhaemoglobin saturation and exhaled nitric oxide during exercise.","authors":"A. Sheel, M. R. Edwards, D. Mckenzie","doi":"10.1097/00005768-199905001-01657","DOIUrl":"https://doi.org/10.1097/00005768-199905001-01657","url":null,"abstract":"Decreases in oxyhaemoglobin saturation (SaO2) are frequently observed in highly trained male endurance athletes during heavy work and has been termed exercise-induced hypoxaemia (EIH). Ventilation perfusion (VA/Q) mismatching and diffusion limitations are thought to be responsible. Nitric oxide (NO), a potent vasodilator, is present in the exhaled air of resting and exercising humans. Endogenously produced NO is thought to play a role in VA/Q matching and maintenance of low pulmonary vascular resistance. The purpose of this study was to determine the relationship between exhaled NO and EIH. It was hypothesized that athletes with EIH would have lower NO levels compared with non-EIH athletes. Eighteen highly trained male cyclists (VO2max=67.7 +/- 5.2 mL kg-1 min-1, mean +/- SD) were divided into normal (NORM, n=12, SaO2= 93.9 +/- 0.8) or low (LOW, n=6, SaO2=90.3 +/- 1.0) group, based on significantly different peak exercise SaO2 values (P < 0.05). All other descriptive and physiological characteristics were similar between the groups. Subjects performed a ramped cycle test to exhaustion breathing NO-free gas. The concentration (CNO) and production rate (VNO) of NO were determined from mixed gas samples at rest and during exercise at 100, 200, 250, 300, 350, 400 and 450 W using a chemiluminescent analyser. CNO remained unchanged from resting values in all subjects. VNO increased significantly during exercise in all subjects but was not different between LOW and NORM groups. The correlation between change in SaO2 and VNO from rest to maximal exercise was not significant (r=-0.12, P > 0.05). Collectively, these data suggest that exhaled NO is not related to decreased SaO2 during heavy exercise in highly trained male cyclists.","PeriodicalId":7160,"journal":{"name":"Acta physiologica Scandinavica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1999-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83738620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Loss of potassium from muscle during moderate exercise in humans: a result of insufficient activation of the Na+-K+-pump?","authors":"E Verburg,&nbsp;J Hallén,&nbsp;O M Sejersted,&nbsp;N K Vøllestad","doi":"10.1046/j.1365-201X.1999.00512.x","DOIUrl":"https://doi.org/10.1046/j.1365-201X.1999.00512.x","url":null,"abstract":"<p><p>In this study, we have investigated whether the muscle net potassium (K+) loss, observed during two-legged intermittent static knee-extensions at 30% MVC (n = 9), is caused by an insufficient activation of the Na+-K+-pumps. Furthermore, we have investigated whether the changes in the K+ homeostasis can be causally related to fatigue. K+ loss was calculated from the arterio-venous concentration difference and plasma flow. In three subjects, femoral venous K+ concentration was measured continuously with a K+ selective electrode. Na+-K+-pump activity was estimated from the rate of removal of K+ from the blood during 30-s pauses inserted into the exercise protocol. A large net K+ loss took place during the first minutes of exercise, but diminished quickly and disappeared after 20 min. An increasing net K+ loss reappeared after 30 min. Only 10% of the lost K+ had been regained after the 20-min recovery. A lag in the activation of the Na+-K+-pumps may explain the K+ loss at the beginning of exercise, but gradual pump activation prevented a net K+ loss after 20 min of exercise. The reappearance of the net K+ loss in the later stage of exercise and the subsequent slow recovery of intracellular K+ seemed to be caused by an insufficient further activation of the pumps, rather than by the capacity of the pumps being surpassed. Fatigue was not related to the accumulation of K+ in the interstitium. However, during exercise, the decrease in intracellular K+ content was linearly related to the fall of maximal force. We conclude that during repeated isometric contractions, insufficient activation of the Na+-K+-pumps causes a continuous muscle K+ loss which was associated with fatigue.</p>","PeriodicalId":7160,"journal":{"name":"Acta physiologica Scandinavica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1999-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21219666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Metoprine-induced thirst and diuresis in Wistar rats.","authors":"A Lecklin,&nbsp;L Eriksson,&nbsp;J Leppäluoto,&nbsp;J Tarhanen,&nbsp;L Tuomisto","doi":"10.1046/j.1365-201X.1999.00513.x","DOIUrl":"https://doi.org/10.1046/j.1365-201X.1999.00513.x","url":null,"abstract":"<p><p>In the present study, the renal responses to metoprine, a histamine-N-methyltransferase inhibitor, were studied in conscious rats. Metoprine (10-20 mg kg(-1)) or vehicle were administered i.p. to male Wistar rats and the effects were followed for the subsequent 24 h. It was found that as early as 3 h after the drug administration metoprine 20 mg kg(-1) had increased water consumption and urine flow approximately 6-8-fold. The treatment decreased urine osmolality and increased free water clearance, but caused no change in plasma renin activity or plasma vasopressin concentration. In addition, a metoprine-induced elevation in the systolic blood pressure was observed during the first few hours of the experiment. During the nocturnal period of the study, glomerular filtration rate and the excretion of electrolytes did not increase in metoprine-treated rats as they did in control rats. A decrease in the release of atrial natriuretic peptide was also found. The present results show that inhibition of histamine catabolism by metoprine causes massive changes in renal functions. It seems to promote water excretion by the kidneys but, on the other hand, to reduce the excretion of electrolytes. Although the exact mechanisms, especially the role of increased blood pressure and nocturnal suppression of atrial natriuretic peptide, require further clarification, the present data suggest that renin-angiotensin system and vasopressin were not involved in these renal responses to metoprine.</p>","PeriodicalId":7160,"journal":{"name":"Acta physiologica Scandinavica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1999-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1046/j.1365-201X.1999.00513.x","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21064084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Proceedings of the Vascular Smooth Muscle Symposium. Margretorp, Sweden, 21-25 May 1998.","authors":"","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":7160,"journal":{"name":"Acta physiologica Scandinavica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21071264","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The bumetanide-resistant part of forskolin-induced anion secretion in rat colon.","authors":"G Schultheiss,&nbsp;S Hörger,&nbsp;M Diener","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>In order to reveal the contribution of the Na(+)-K(+)-2 Cl(-)- cotransporter to forskolin-induced anion secretion, the inhibition of forskolin-stimulated short-circuit current (Isc) by bumetanide, furosemide, azosemide and piretanide was investigated. In the distal colon, all blockers inhibited the forskolin-stimulated Isc with a maximal efficiency of 70%. In contrast, in the proximal colon, bumetanide and furosemide inhibited only about 40% of the forskolin response, whereas piretanide and azosemide were ineffective. A similar result was observed, when Na+ was replaced by impermeant cations suggesting especially in the proximal colon a great part of forskolin-induced anion secretion to be independent of the Na(+)-K(+)-2 Cl(-)-cotransporter. In anion substitution experiments the forskolin-induced increase in Isc was reduced by 70-80%, if either Cl- or HCO3- were omitted from the buffer solution, whereas in the combined absence of both anions the response was nearly suppressed. Measurement of the mucosal alkalinization revealed that forskolin stimulated a HCO3- secretion, which was, however, too weak to explain the bumetanide-insensitive Isc induced by forskolin. Bumetanide inhibited the serosa-to-mucosa flux of Cl- (JsmCl) stimulated by forskolin; an effect, which was strongly enhanced by subsequent administration of the anion exchange inhibitor, SITS. These data suggest that the bumetanide-resistant part of the forskolin-induced Isc is mainly mediated by a basolateral anion exchanger, probably a Cl(-)-HCO3- exchanger, which contributes to forskolin-evoked Cl- secretion, and in addition by a small HCO3- secretion stimulated by the drug.</p>","PeriodicalId":7160,"journal":{"name":"Acta physiologica Scandinavica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20716921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Muscle performance--fatigue, recovery and trainability.","authors":"O M Sejersted,&nbsp;N K Vøllestad,&nbsp;J Hallén,&nbsp;R Bahr","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":7160,"journal":{"name":"Acta physiologica Scandinavica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20498453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Na+/glucose cotransport in the colonic adenocarcinoma cell line HT29 cl.19A: effect of cAMP.","authors":"M Hemlin,&nbsp;X Huang","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The aim of the present study was to investigate the earlier finding that cAMP stimulation activates Na+/glucose cotransport in intestinal epithelia. Western blotting demonstrated the existence of Na+/glucose cotransporters in the colonic adenocarcinoma cell line HT29 cl.19A. Monolayers of this cell type showed a glucose transport, which was inhibited by 0.5 mM phlorizin (specific inhibitor of Na+/glucose cotransport). Brush border membrane vesicles of HT29 cl.19A cells exhibited a Na(+)-gradient dependent glucose transport, which was stimulated by DbcAMP-pretreatment (dibutyryladenosine 3',5'-cyclic monophosphate) of the cells. In the Ussing chamber, glucose (10 mM) unexpectedly lacked stimulatory effect on short circuit current (Isc) in HT29 cl.19A monolayers in the control situation. In DbcAMP-stimulated monolayers, glucose induced a complex Isc-response consisting of both stimulatory and inhibitory components, usually leading to a 'net' stimulation of lsc. Phlorizin (0.5 mM) did not prevent the stimulatory effect of glucose. Mannitol, alanine, fructose, ethanol (solvent for phlorizin) and the non-metabolizable glucose analogue 3-o-methyl-alpha-glucopyranoside inhibited Isc in a similar fashion as did phlorizin. Glucose transport in human colon biopsies were studied both in [14C]glucose accumulation experiments and in a specially designed Ussing chamber. There were no indications of glucose absorption in neither of these experiments. We conclude: (1) The human colon lacks Na+/glucose transport, (2) HT29 cl.19A cells exhibit Na+/glucose cotransport, which is stimulated by cAMP, (3) but this mechanism seem to be of a different type from the Na+/glucose cotransport of the 'normal' small intestine.</p>","PeriodicalId":7160,"journal":{"name":"Acta physiologica Scandinavica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1997-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20153688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Increased left ventricular muscle mass after long-term altitude training in athletes.","authors":"J. Svedenhag, K. Piehl‐aulin, Christer Skog, B. Saltin","doi":"10.1097/00005768-199705001-00809","DOIUrl":"https://doi.org/10.1097/00005768-199705001-00809","url":null,"abstract":"The effects of long-term altitude training on altitude and sea-level physiological characteristics in elite endurance athletes were investigated. Seven Swedish elite cross-country skiers (five men, two women; mean age 27 years) spent 1 month training at 1900 m above sea level in Italy. Rollerski treadmill tests were performed before and 5 and 11 days after the altitude sojourn; three tests were also performed at altitude. Before and 1, 11 and 35 days after the altitude camp, echocardiographic and blood volume measurements were performed. The heart rates at both maximal (P < 0.05) and submaximal (P < 0.01) work loads were decreased by 5-9 beats min-1 at altitude. The haemoglobin concentration and haematocrit increased quickly at altitude with a corresponding decrease on return to sea level. The blood volume (7%) and total haemoglobin (3%) tended to be higher day 11 post-altitude (NS). There were no significant changes in diastolic internal diameter or wall thickness of the left ventricle, but the calculated cardiac left ventricular muscle mass was increased post-altitude (9-10%, P < 0.01). The maximal oxygen uptake increased in six of the seven skiers after the altitude training (day 11, mean 3%, NS). In conclusion, training at moderate altitude may cause a reduction in heart rates during exercise. Moreover, after long-term training at altitude, there may be an increase in the cardiac left ventricular muscle mass.","PeriodicalId":7160,"journal":{"name":"Acta physiologica Scandinavica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1997-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72929294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Total blood volume in endurance-trained postmenopausal females: relation to exercise mode and maximal aerobic capacity.","authors":"P. Parker Jones, K. Davy, C. DeSouza, H. Tanaka","doi":"10.1097/00005768-199705001-00625","DOIUrl":"https://doi.org/10.1097/00005768-199705001-00625","url":null,"abstract":"We have recently shown that postmenopausal female distance runners demonstrate elevated levels of blood volume compared with sedentary healthy peers. We also found a strong positive relation between blood volume and maximal oxygen consumption. In young adult males, endurance exercise training increases blood volume when performed in the upright, but not in the supine body position. Based on these observations, we hypothesized that among postmenopausal females, the elevation in blood volume would be absent or attenuated in women who train in the horizontal vs. upright body position, and that the lower blood volume in the former would be associated with lower maximal aerobic capacity. Thus, we measured supine resting plasma and total blood volumes (Evans blue dye) and maximal oxygen consumption in postmenopausal women: 10 sedentary controls, 10 swimmers and 10 runners matched for age (60 +/- 2; 59 +/- 2; 58 +/- 2 years, mean +/- SE) and hormone replacement use (5 per group). The swimmers and runners were further matched for training volume (4.5 +/- 0.2 vs. 4.8 +/- 0.6 h week-1), relative performance (78 +/- 5 vs. 75 +/- 3% of age-group world record) and fat-free mass (45.5 +/- 0. 8 vs. 44.9 +/- 1.5 kg). Total blood volume and maximal oxygen consumption were highest in the runners (81.2 +/- 4; 52.4 +/- 3 mL kg-1, respectively) and progressively lower in the swimmers (68.8 +/- 3; 44.2 +/- 2) and controls (59.2 +/- 2; 37.9 +/- 2; all P < 0. 05). In the pooled population, blood volume was positively related to maximal oxygen consumption (r = 0.72, P < 0.0001). We conclude that in endurance-trained postmenopausal females matched for training volume and competitive performance: (1) blood volume is lower in those who train in the horizontal (swimmers) compared with the upright position (runners); (2) the lower blood volume is associated with a lower maximal aerobic capacity. Nevertheless, blood volume and maximal oxygen consumption are higher in postmenopausal women who train in the horizontal position than in sedentary controls.","PeriodicalId":7160,"journal":{"name":"Acta physiologica Scandinavica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1997-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78701074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Apical secretion of rat submandibular tissue kallikrein continues in the absence of external stimulation: evidence for a constitutive secretory pathway.","authors":"J R Garrett,&nbsp;X S Zhang,&nbsp;G B Proctor,&nbsp;L C Anderson,&nbsp;D K Shori","doi":"10.1046/j.1365-201X.1996.436163000.x","DOIUrl":"https://doi.org/10.1046/j.1365-201X.1996.436163000.x","url":null,"abstract":"<p><p>Sequential samples of saliva evoked by low frequency parasympathetic nerve stimulation were collected from cannulated submandibular ducts of anaesthetized rats following periods of varying length without stimulation. After such rest periods the first samples of saliva were found to contain much higher levels of tissue kallikrein (rK1) activity and protein than the ensuing samples from the same stimulation period and the latter contained levels similar to those found previously in parasympathetically-evoked saliva. rK1 activity in first samples increased with the length of the preceding interval, indicating that a continuous secretion of rK1 occurs from ductal cells into glandular lumina and accumulates there in the absence of stimulation or fluid secretion. The protein secretory pattern following rest pauses was unaffected by alpha-adrenergic receptor blockade and a high percentage of the proteinase activity was resistant to soya bean trypsin inhibitor, showing that the secretion was not caused by exocytosis of storage granules from ductal cells and therefore was likely to be a result of a constitutive secretion of newly synthesized enzyme. The pattern of continuous secretion into lumina detected for total protein in the absence of stimulation, suggests that other secretory proteins may also be secreted similarly but at different rates.</p>","PeriodicalId":7160,"journal":{"name":"Acta physiologica Scandinavica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19834291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}