A multi-organ map of the human immune system across age, sex and ethnicity.

Understanding tissue biology's heterogeneity is crucial for advancing precision medicine. Despite the centrality of the immune system in tissue homeostasis, a detailed and comprehensive map of immune cell distribution and interactions across human tissues and demographics remains elusive. To fill this gap, we harmonised data from 12,981 single-cell RNA sequencing samples and curated 29 million cells from 45 anatomical sites to create a comprehensive compositional and transcriptional healthy map of the healthy immune system. We used this resource and a novel multilevel modelling approach to track immune ageing and test differences across sex and ethnicity. We uncovered conserved and tissue-specific immune-ageing programs, resolved sex-dependent differential ageing and identified ethnic diversity in clinically critical immune checkpoints. This study provides a quantitative baseline of the immune system, facilitating advances in precision medicine. By sharing our immune map, we hope to catalyse further breakthroughs in cancer, infectious disease, immunology and precision medicine.

Outcomes following supervised exercise and home-based exercise for patients with intermittent claudication.

INTRODUCTION: Intermittent claudication (IC) is the most common symptom of peripheral arterial disease (PAD) which presents as a consequence of muscle ischaemia resulting from the atherosclerotic obstruction to arterial flow. High-quality evidence (Lane et al., 2017) shows that exercise programmes provide important benefits compared with usual care in improving pain-free and maximum walking distance in people with IC, but do not improve ankle-brachial pressure index (ABPI). METHODS: Retrospective data were analysed to examine walking and ABPI outcomes for participants who completed a 12-week course of supervised or home-based exercise. All participants had a history of IC. RESULTS: 46 participants (mean age 69±11 years; 76% male; 29% current smokers) referred for exercise were assessed, completed a 12-week course of exercise (home-based or supervised) and subsequently attended for re-assessment. Claudication onset distance (COD) increased by 363% (mean improvement 344.7 ± 265.1m; p < .001) and peak walking distance (PWD) by 324.4% in the supervised exercise group; COD increased by 30.6% (mean improvement 32.8 ± 57.2 m; p = 0.026) and PWD by 31.5% in the home-based exercise group. Resting ABPI for the total cohort significantly improved from 0.82 ± 0.25 at A1 to 0.88 ± 0.25 at A2 (p = 0.027). DISCUSSION: A 12-week course of supervised exercise results in significantly greater walking distance outcomes (COD and PWD) than unmonitored home-based exercise. In contrast with previous findings (Lane et al. 2017), this retrospective study demonstrated a significant improvement in resting ABPI with both supervised exercise as well as home-based exercise. CONCLUSION: A 12-week programme of exercise favourably influenced walking and ABPI outcomes for patients with IC. Both home-based exercise and supervised individualised exercise increased walking distances, but the magnitude of the improvement in walking outcomes was greater in individuals who attended supervised exercise therapy.

Incidence, prevalence, and treatment patterns in metastatic hormone-sensitive prostate cancer in Spain: ECHOS study.

INTRODUCTION AND OBJECTIVE: The management of patients with metastatic hormone-sensitive prostate cancer (mHSPC) has changed in recent years due to the approval of new drugs. The aim of this study was to evaluate the prevalence, incidence, and treatment patterns in mHSPC in Spain. PATIENTS AND METHODS: Multicenter, observational, longitudinal, retrospective study in routine clinical practice of patients diagnosed with mHSPC treated in Spanish hospitals between 2015 and 2019 (ECHOS study). Electronic medical records were extracted from BIG-PAC database, which contains geographically representative Spanish centers. RESULTS: Data from 379 men with mHSPC were included. The prevalence of mHSPC ranged between 12.2-14.6% per year, representing from 671 to 824 annual cases with an increasing trend. The mean incidence along the 4-year period was 2.5%, with annual incidence ranging 2.2-3.0%. New annual cases of de novo and recurrent disease ranged between 7-11 and 77-104, respectively, with no trend being observed. These patients were mostly recurrent (91%) with high-volume disease (68.6%). The most common first-line therapy was ADT combined with docetaxel (53%), followed by ADT alone (23.8%), combination of ADT and abiraterone (11.2%), and radiotherapy (8.6%). In the last 12 months before diagnosis of metastasis, most men had been submitted to radical prostatectomy (84.9%). The remaining patients had received radiotherapy (12%) or no treatment at all (3.8%). CONCLUSIONS: The ECHOS study provides epidemiologic data and current patterns of treatment in clinical practice of patients with mHSPC in Spain. These results emphasize the medical need of targeted treatments in these clinical settings.

Surgical cognitive simulation improves real-world surgical performance: randomized study.

BACKGROUND: Despite the acknowledgement of human factors, application of psychological methods by surgeons to improve surgical performance is sparse. This may reflect the paucity of evidence that would help surgeons to use psychological techniques effectively. There is a need for novel approaches to see how cognitive training might be used to address these challenges. METHODS: Surgical trainees were divided into intervention and control groups. The intervention group received training in surgical cognitive simulation (SCS) and was asked to apply the techniques while working in operating theatres. Both groups underwent procedure-based assessment based on the UK and Ireland Intercollegiate Surgical Curriculum Programme (ISCP) before the training and 4 months afterwards. Subjective evaluations of SCS application were obtained from the intervention group participants. RESULTS: Among 21 participants in the study, there was a statistically significant improvement in 11 of 16 procedure-based assessment domains (P < 0.050) as well as a statistically significant mean reduction in time to complete the procedure in the intervention group (-15.98 versus -1.14 min; P = 0.024). Subjectively, the intervention group experienced various benefits with SCS, especially in preoperative preparedness, intraoperative focus, and overall performance. CONCLUSION: SCS training has a statistically significant impact in improving surgical performance. Subjective feedback suggests that surgeons are able to apply it in practice. SCS may prove a vital adjunct for skill acquisition in surgical training.

Four days of simulated shift work reduces insulin sensitivity in humans.

AIM: The aim of this study was to investigate the effects of 4 consecutive simulated night shifts on glucose homeostasis, mitochondrial function and central and peripheral rhythmicities compared with a simulated day shift schedule. METHODS: Seventeen healthy adults (8M:9F) matched for sleep, physical activity and dietary/fat intake participated in this study (night shift work n = 9; day shift work n = 8). Glucose tolerance and insulin sensitivity before and after 4 nights of shift work were measured by an intravenous glucose tolerance test and a hyperinsulinaemic euglycaemic clamp respectively. Muscles biopsies were obtained to determine insulin signalling and mitochondrial function. Central and peripheral rhythmicities were assessed by measuring salivary melatonin and expression of circadian genes from hair samples respectively. RESULTS: Fasting plasma glucose increased (4.4 ± 0.1 vs. 4.6 ± 0.1 mmol L-1 ; P = .001) and insulin sensitivity decreased (25 ± 7%, P < .05) following the night shift, with no changes following the day shift. Night shift work had no effect on skeletal muscle protein expression (PGC1α, UCP3, TFAM and mitochondria Complex II-V) or insulin-stimulated pAkt Ser473, pTBC1D4Ser318 and pTBC1D4Thr642. Importantly, the metabolic changes after simulated night shifts occurred despite no changes in the timing of melatonin rhythmicity or hair follicle cell clock gene expression across the wake period (Per3, Per1, Nr1d1 and Nr1d2). CONCLUSION: Only 4 days of simulated night shift work in healthy adults is sufficient to reduce insulin sensitivity which would be expected to increase the risk of T2D.

Is it necessary to diagnose levator avulsion on pelvic floor muscle contraction?

OBJECTIVE: Avulsion of the levator ani muscle commonly occurs at vaginal birth. This condition is usually diagnosed by translabial ultrasound (TLUS) during pelvic floor muscle contraction (PFMC). Some patients are unable to achieve a satisfactory PFMC and in these cases avulsion is assessed at rest. The aim of this study was to validate the diagnosis of levator avulsion by means of TLUS at rest. METHODS: This was a retrospective study of 233 women seen at a tertiary urogynecological center. All women underwent four-dimensional TLUS in the supine position and after voiding. Volumes were obtained on maximal PFMC and at rest. Analysis of the volumes was performed with the observer blinded against all clinical data. Avulsion was defined as an abnormal levator ani muscle insertion that was visible in at least three consecutive axial plane slices, at and above the level of minimal hiatal dimensions, at 2.5-mm intervals. We examined the correlation between both assessment methods using Cohen's kappa coefficient and tested the association of each method with female pelvic organ prolapse on clinical examination, organ descent on ultrasound and hiatal ballooning. RESULTS: In total, datasets from 202 women were available for analysis. The correlation between a diagnosis of avulsion in volumes obtained at rest and those on PFMC was moderate, with a kappa value of 0.583 (95% CI, 0.484-0.683). Agreement for defects visualized on single slices was moderate, with a kappa value of 0.556 (95% CI, 0.520-0.591). When avulsion diagnoses at rest and on PFMC were tested against symptoms of prolapse, and prolapse on clinical examination and on ultrasound, neither of the two methods was superior. CONCLUSION: Although tomographic ultrasound imaging during PFMC enhances tissue discrimination, this may not translate to superior diagnostic performance. Hence, volumes obtained at rest may be used in women unable to contract their pelvic floor. The diagnosis of levator avulsion by tomographic pelvic floor ultrasound is equally valid when performed at rest or on PFMC. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Striated muscle activator of Rho signalling (STARS) is reduced in ageing human skeletal muscle and targeted by miR-628-5p.

AIM: The striated muscle activator of Rho signalling (STARS) is a muscle-specific actin-binding protein. The STARS signalling pathway is activated by resistance exercise and is anticipated to play a role in signal mechanotransduction. Animal studies have reported a negative regulation of STARS signalling with age, but such regulation has not been investigated in humans. METHODS: Ten young (18-30 years) and 10 older (60-75 years) subjects completed an acute bout of resistance exercise. Gene and protein expression of members of the STARS signalling pathway and miRNA expression of a subset of miRNAs, predicted or known to target members of STARS signalling pathway, were measured in muscle biopsies collected pre-exercise and 2 h post-exercise. RESULTS: For the first time, we report a significant downregulation of the STARS protein in older subjects. However, there was no effect of age on the magnitude of STARS activation in response to an acute bout of exercise. Finally, we established that miR-628-5p, a miRNA regulated by age and exercise, binds to the STARS 3'UTR to directly downregulate its transcription. CONCLUSION: This study describes for the first time the resistance exercise-induced regulation of STARS signalling in skeletal muscle from older humans and identifies a new miRNA involved in the transcriptional control of STARS.

The incidence of hypomagnesaemia following abdominal aortic aneurysm surgery.

INTRODUCTION: Magnesium is important for cardiac function. Hypomagnesaemia is associated with a higher incidence of arrhythmias and poorer outcomes in cardiac surgery. No studies have investigated the incidence or impact of postoperative hypomagnesaemia after abdominal aortic aneurysm (AAA) surgery. We aim to assess the incidence of hypomagnesaemia after AAA repair in our population. METHODS: Retrospective analysis was performed of patients who underwent elective AAA surgery at a single vascular centre. The last 110 patients undergoing open or endovascular AAA repair were identified. The hospital pathology system was used to identify the immediate postoperative serum magnesium levels as well as patient demographics and admission details. Hypomagnesaemia was defined as serum magnesium of <0.7 mmol/l. RESULTS: A total of 211 patients were studied and there were 3 deaths. Of the patients included, 101 underwent open elective AAA repair and 110 underwent endovascular repair. In the elective open repair group, 73 patients (73%) were hypomagnesaemic. In the endovascular repair group, 35 (32%) had hypomagnesaemia. A t-test showed a statistically significant difference in hypomagnesaemia between the open and endovascular groups (p<0.001). CONCLUSIONS: AAA surgery is associated with a high incidence of postoperative hypomagnesaemia, which is significantly greater among open repair patients. This is likely to have an effect on cardiac activity and lead to cardiac complications such as arrhythmias and poorer postoperative outcomes, especially in the open AAA repair subgroup. This stresses the importance of serum magnesium and cardiac monitoring in the postoperative phase. A prospective study is proposed to further investigate these findings, and their potential implications on perioperative morbidity and mortality.

Exercise increases skeletal muscle GLUT4 gene expression in patients with type 2 diabetes.

The aim of the study was to determine the effect of a single bout of exercise on GLUT4 gene expression in muscle of patients with type 2 diabetes (T2D) and control subjects, matched for age and body mass index. Nine patients with T2D and nine control subjects performed 60 min of cycling exercise at ~55% peak power (W(max) ). Skeletal muscle biopsies were obtained at baseline, immediately post and 3-h post exercise. GLUT4 mRNA expression increased (p < 0.05) to a similar extent immediately post exercise in control (~60%) and T2D (~66%) subjects, and remained elevated (p < 0.05) 3-h post exercise with no differences between groups. Similarly, p-AMP-activated protein kinase, p38 mitogen-activated kinase and proliferator-activated receptor gamma co-activator-alpha mRNA expression were increased (p < 0.05) post exercise, and were not different between the groups. In conclusion, a single bout of exercise increased skeletal muscle GLUT4 mRNA expression in patients with T2D to a similar extent as in control subjects.

Vitamin D status and musculoskeletal health in adolescent male ballet dancers a pilot study.

Adequate vitamin D levels during growth are critical to ensuring optimal bone development. Vitamin D synthesis requires sun exposure; thus, athletes engaged in indoor activities such as ballet dancing may be at relatively high risk of vitamin D insufficiency. The objective of this study was to investigate the prevalence of low vitamin D levels in young male ballet dancers and its impact on musculoskeletal health. Eighteen male ballet dancers, aged 10 to 19 years and training for at least 6 hours per week, were recruited from the Australian Ballet School, Melbourne, Australia. Serum 25(OH)D and intact PTH were measured in winter (July) from a non-fasting blood sample. Pubertal stage was determined using self-assessed Tanner criteria. Body composition and areal bone mineral density (aBMD) at the whole body and lumbar spine were measured using dual-energy x-ray absorptiometry (DXA). Injury history and physical activity levels were assessed by questionnaire. Blood samples were obtained from 16 participants. Serum 25(OH)D levels ranged from 20.8 to 94.3 nmol/L, with a group mean of 50.5 nmol/L. Two participants (12.5%) showed vitamin D deficiency [serum 25(OH)D level < 25 nmol/L], seven dancers (44%) had vitamin D insufficiency (25 to 50 nmol/L), and the remaining seven dancers (44%) had normal levels (> 50 nmol/L). No relationship was found between vitamin D status, PTH levels, body composition, and aBMD. The most commonly reported injuries were muscle tears and back pain. The average number of injuries reported by each dancer was 1.9 ± 0.4 (range: 0 to 5). There was no difference in the frequency of reported injuries between subjects with vitamin D deficiency or insufficiency (2.1 ± 0.6 injuries) and those with normal vitamin D levels (1.4 ± 0.6 injuries). This pilot study showed that more than half of highly-trained young male ballet dancers presented with low levels of vitamin D in winter. Further investigations in larger samples of adolescent athletes are needed to determine if this could negatively impact bone growth and place them at higher risk for musculoskeletal injuries.

Exercise training increases adipose tissue GLUT4 expression in patients with type 2 diabetes.

We investigated the effects of exercise training on adipose tissue and skeletal muscle GLUT4 expression in patients with type 2 diabetes (T2D). Muscle and adipose tissue samples were obtained before and after 4-weeks of exercise training in seven patients with T2D [47 ± 2 years, body mass index (BMI) 28 ± 2]. Seven control subjects (54 ± 4, BMI 30 ± 2) were recruited for baseline comparison. Adipose tissue GLUT4 protein expression was 43% lower (p < 0.05) in patients with T2D compared with control subjects and exercise training increased (p < 0.05) adipose tissue GLUT4 expression by 36%. Skeletal muscle GLUT4 protein expression was not different between control subjects and patients with T2D. Exercise training increased (p < 0.05) skeletal muscle GLUT4 protein expression by 20%. In conclusion, 4-weeks of exercise training increased GLUT4 expression in adipose tissue and skeletal muscle of patients with T2D, although the functional benefits of this adaptation appear to be dependent on an optimal ß-cell function.

Health-related quality of life improvement following surgical treatment of primary hyperparathyroidism in a United Kingdom population.

OBJECTIVE: The aim of this study was to determine if parathyroidectomy for primary hyperparathyroidism produces improvement in health-related quality of life in a United Kingdom population. METHODS: Since October 2002, patients undergoing parathyroidectomy for primary hyperparathyroidism were asked to complete the SF-36 questionnaire, a validated self assessment tool prior to surgery and at six months post surgery. The questionnaires were either mailed to the patients or given at the time of outpatient follow up. RESULTS: 24 out of 29 patients completed the questionnaire pre- and postoperatively. Compared to the national average, the median pre-operative scores were worse in all 8 domains. At 6 months post surgery, there were significant improvements in six out of eight domains (p<0.05); physical and social functioning, physical and emotional role limitations, energy and mental health. The median physical component summary score (PCS) and the mental component summary score (MCS) were also significantly improved postoperatively [Preop vs. Postop (PCS)=28.16 vs. 35.40 (P=0.03)] and Preop vs. Postop (MCS)=41.50 vs. 56.23 (P=0.005)]. The post-operative MCS was comparable with the national average. CONCLUSION: This study shows that parathyroidectomy for primary hyperparathyroidism improves health-related quality of life in a United Kingdom population.

Inflammation, hepatic enzymes and resistance training in individuals with metabolic risk factors.

AIMS: Increases in inflammatory markers, hepatic enzymes and physical inactivity are associated with the development of the metabolic syndrome (MetS). We examined whether inflammatory markers and hepatic enzymes are correlated with traditional risk factors for MetS and studied the effects of resistance training (RT) on these emerging risk factors in individuals with a high number of metabolic risk factors (HiMF, 2.9 +/- 0.8) and those with a low number of metabolic risk factors (LoMF, 0.5 +/- 0.5). METHODS: Twenty-eight men and 27 women aged 50.8 +/- 6.5 years (mean +/- sd) participated in the study. Participants were randomized to four groups, HiMF training (HiMFT), HiMF control (HiMFC), LoMF training (LoMFT) and LoMF control (LoMFC). Before and after 10 weeks of RT [3 days/week, seven exercises, three sets with intensity gradually increased from 40-50% of one repetition maximum (1RM) to 75-85% of 1RM], blood samples were obtained for the measurement of pro-inflammatory cytokines, C-reactive protein (CRP), gamma-glutamyltransferase (GGT) and alanine aminotransferase (ALT). RESULTS: At baseline, HiMF had higher interleukin-6 (33.9%), CRP (57.1%), GGT (45.2%) and ALT (40.6%) levels, compared with LoMF (all P < 0.05). CRP, GGT and ALT correlated with the number of risk factors (r = 0.48, 0.51 and 0.57, respectively, all P < 0.01) and with other anthropometric and clinical measures (r range from 0.26 to 0.60, P < 0.05). RT did not significantly alter inflammatory markers or hepatic enzymes (all P > 0.05). CONCLUSIONS: HiMF was associated with increased inflammatory markers and hepatic enzyme concentrations. RT did not reduce inflammatory markers and hepatic enzymes in individuals with HiMF.

Attenuation of changes in capillary fine structure and leukocyte adhesion improves muscle performance following chronic ischaemia in rats.

Acute ischaemia-reperfusion disrupts capillary fine structure and increases leukocyte adhesion in postcapillary venules. We determined whether chronic muscle ischaemia has similar consequences, and whether it is possible to ameliorate its effect on muscle performance. Following ischaemia (unilateral ligation, common iliac artery) rat hindlimb muscles were examined without other intervention or following treatment with an xanthine oxidase inhibitor (allopurinol), a Na(+)/H(+) exchange blocker (amiloride), or an oxygen free radical scavenger (vitamin E). No significant leukocyte adhesion or rolling, nor changes in capillary fine structure were observed 3 days postsurgery, when limb use was limited. However, leukocyte rolling and adhesion almost trebled by 7 days (P < 0.001), when normal gait was largely restored. Capillary fine structure was disturbed over a similar time course, e.g. relative endothelial volume (control 46%, 7 days 61%; P < 0.05), that resolved by 5 weeks. Where activity was increased by mild electrical stimulation 3 days after ligation muscles showed enhanced capillary swelling (endothelial volume 66% versus 50%, P < 0.005), but improved fatigue index (52% versus 16%, P < 0.001) as a result of greater blood flow. Muscle fatigue after ligation was related to the extent of contraction-induced hyperaemia (R(2) = 0.725), but not capillary swelling. Amiloride, and to a lesser extent allopurinol but not vitamin E, significantly decreased leukocyte rolling and adhesion, as well as capillary endothelial swelling. We conclude that increased activity of ischaemic muscles on recovery is likely to accentuate acidosis accompanying changes in microcirculation and contribute to enhanced muscle fatigue, whereas formation of oxygen free radicals may be attenuated by endogenous protective mechanisms.

Temporal artery biopsy: impact on the clinical management of patients.

OBJECTIVES: Temporal artery biopsy (TAB) is requested in an attempt to confirm the diagnosis of temporal arteritis (TA). Patients symptoms and signs are highly variable and TA is often focal and potentially missed in a small biopsy. The study aimed to determine if TAB helps in the management of patients with suspected TA. METHODS: The case records of sixty-six consecutive patients who had undergone temporal artery biopsy were recalled and examined for presenting symptoms, management, therapy, results and outcome. RESULTS: There were 23 men and 43 women with a mean age of 70.2 and 71.1 years respectively. Presenting symptoms varied with unilateral headache in 53, scalp tenderness in 16, muscle weakness in 10, visual disturbance in 16, jaw claudication in 5 and peri-orbital pain in 1 patient. The temporal artery was tender in 21 patients and thickened in 4 patients. Thirty-eight patients were commenced on steroids prior to biopsy and 6 more before the histology became available. Only 8% of biopsies were positive for TA. Of the patients started on steroids with a negative biopsy, the steroids were continued in 26 and stopped in 9. In the patients not put on steroids [22], biopsy was positive in 2; they were commenced on steroids. Therefore, the histological diagnosis resulted in a change in patient management in only 18% of patients. CONCLUSION: The results of TAB do not appear to affect the clinical management of most patients with suspected temporal arteritis. We must therefore question the routine use of this invasive investigation.

Muscle Na+-K+-ATPase activity and isoform adaptations to intense interval exercise and training in well-trained athletes.

The Na+ -K+ -ATPase enzyme is vital in skeletal muscle function. We investigated the effects of acute high-intensity interval exercise, before and following high-intensity training (HIT), on muscle Na+ -K+ -ATPase maximal activity, content, and isoform mRNA expression and protein abundance. Twelve endurance-trained athletes were tested at baseline, pretrain, and after 3 wk of HIT (posttrain), which comprised seven sessions of 8 x 5-min interval cycling at 80% peak power output. Vastus lateralis muscle was biopsied at rest (baseline) and both at rest and immediately postexercise during the first (pretrain) and seventh (posttrain) training sessions. Muscle was analyzed for Na+ -K+ -ATPase maximal activity (3-O-MFPase), content ([3H]ouabain binding), isoform mRNA expression (RT-PCR), and protein abundance (Western blotting). All baseline-to-pretrain measures were stable. Pretrain, acute exercise decreased 3-O-MFPase activity [12.7% (SD 5.1), P < 0.05], increased alpha1, alpha2, and alpha3 mRNA expression (1.4-, 2.8-, and 3.4-fold, respectively, P < 0.05) with unchanged beta-isoform mRNA or protein abundance of any isoform. In resting muscle, HIT increased (P < 0.05) 3-O-MFPase activity by 5.5% (SD 2.9), and alpha3 and beta3 mRNA expression by 3.0- and 0.5-fold, respectively, with unchanged Na+ -K+ -ATPase content or isoform protein abundance. Posttrain, the acute exercise induced decline in 3-O-MFPase activity and increase in alpha1 and alpha3 mRNA each persisted (P < 0.05); the postexercise 3-O-MFPase activity was also higher after HIT (P < 0.05). Thus HIT augmented Na+ -K+ -ATPase maximal activity despite unchanged total content and isoform protein abundance. Elevated Na+ -K+ -ATPase activity postexercise may contribute to reduced fatigue after training. The Na+ -K+ -ATPase mRNA response to interval exercise of increased alpha- but not beta-mRNA was largely preserved posttrain, suggesting a functional role of alpha mRNA upregulation.

Prolonged submaximal exercise induces isoform-specific Na+-K+-ATPase mRNA and protein responses in human skeletal muscle.

This study investigated effects of prolonged submaximal exercise on Na+-K+-ATPase mRNA and protein expression, maximal activity, and content in human skeletal muscle. We also investigated the effects on mRNA expression of the transcription initiator gene, RNA polymerase II (RNAP II), and key genes involved in protein translation, eukaryotic initiation factor-4E (eIF-4E) and 4E-binding protein 1 (4E-BP1). Eleven subjects (6 men, 5 women) cycled at 75.5% (SD 4.8%) peak O2 uptake and continued until fatigue. A vastus lateralis muscle biopsy was taken at rest, fatigue, and 3 and 24 h postexercise. We analyzed muscle for Na+-K+-ATPase alpha1, alpha2, alpha3, beta1, beta2, and beta3, as well for RNAP II, eIF-4E, and 4E-BP1 mRNA expression by real-time RT-PCR and Na+-K+-ATPase isoform protein abundance using immunoblotting. Muscle homogenate maximal Na+-K+-ATPase activity was determined by 3-O-methylfluorescein phosphatase activity and Na+-K+-ATPase content by [3H]ouabain binding. Cycling to fatigue [54.5 (SD 20.6) min] immediately increased alpha3 (P = 0.044) and beta2 mRNA (P = 0.042) by 2.2- and 1.9-fold, respectively, whereas alpha1 mRNA was elevated by 2.0-fold at 24 h postexercise (P = 0.036). A significant time main effect was found for alpha3 protein abundance (P = 0.046). Exercise transiently depressed maximal Na+-K+-ATPase activity (P = 0.004), but Na+-K+-ATPase content was unaltered throughout recovery. Exercise immediately increased RNAP II mRNA by 2.6-fold (P = 0.011) but had no effect on eIF-4E and 4E-BP1 mRNA. Thus a single bout of prolonged submaximal exercise induced isoform-specific Na+-K+-ATPase responses, increasing alpha1, alpha3, and beta2 mRNA but only alpha3 protein expression. Exercise also increased mRNA expression of RNAP II, a gene initiating transcription, but not of eIF-4E and 4E-BP1, key genes initiating protein translation.

Depressed Na+-K+-ATPase activity in skeletal muscle at fatigue is correlated with increased Na+-K+-ATPase mRNA expression following intense exercise.

We investigated whether depressed muscle Na(+)-K(+)-ATPase activity with exercise reflected a loss of Na(+)-K(+)-ATPase units, the time course of its recovery postexercise, and whether this depressed activity was related to increased Na(+)-K(+)-ATPase isoform gene expression. Fifteen subjects performed fatiguing, knee extensor exercise at approximately 40% maximal work output per contraction. A vastus lateralis muscle biopsy was taken at rest, fatigue, 3 h, and 24 h postexercise and analyzed for maximal Na(+)-K(+)-ATPase activity via 3-O-methylfluorescein phosphatase (3-O-MFPase) activity, Na(+)-K(+)-ATPase content via [(3)H]ouabain binding sites, and Na(+)-K(+)-ATPase alpha(1)-, alpha(2)-, alpha(3)-, beta(1)-, beta(2)- and beta(3)-isoform mRNA expression by real-time RT-PCR. Exercise [352 (SD 267) s] did not affect [(3)H]ouabain binding sites but decreased 3-O-MFPase activity by 10.7 (SD 8)% (P < 0.05), which had recovered by 3 h postexercise, without further change at 24 h. Exercise elevated alpha(1)-isoform mRNA by 1.5-fold at fatigue (P < 0.05). This increase was inversely correlated with the percent change in 3-O-MFPase activity from rest to fatigue (%Delta3-O-MFPase(rest-fatigue)) (r = -0.60, P < 0.05). The average postexercise (fatigue, 3 h, 24 h) alpha(1)-isoform mRNA was increased 1.4-fold (P < 0.05) and approached a significant inverse correlation with %Delta3-O-MFPase(rest-fatigue) (r = -0.56, P = 0.08). Exercise elevated alpha(2)-isoform mRNA at fatigue 2.5-fold (P < 0.05), which was inversely correlated with %Delta3-O-MFPase(rest-fatigue) (r = -0.60, P = 0.05). The average postexercise alpha(2)-isoform mRNA was increased 2.2-fold (P < 0.05) and was inversely correlated with the %Delta3-O-MFPase(rest-fatigue) (r = -0.68, P < 0.05). Nonsignificant correlations were found between %Delta3-O-MFPase(rest-fatigue) and other isoforms. Thus acute exercise transiently decreased Na(+)-K(+)-ATPase activity, which was correlated with increased Na(+)-K(+)-ATPase gene expression. This suggests a possible signal-transduction role for depressed muscle Na(+)-K(+)-ATPase activity with exercise.