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Choi MD, Carrithers JA, Gavin TP, Kraus RM, Evans CA, Ruster RS, Knapp DJ, McCartney JS, Garry JP, Hickner RC. Response of prostaglandins and nutritive blood flow to 7 days of exercise training in young and aged human skeletal muscle. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.753.6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Wooldridge AA, Fortner CN, Lontay B, Akimoto T, Neppl RL, Facemire C, Datto MB, Kwon A, McCook E, Li P, Wang S, Thresher RJ, Miller SE, Perriard JC, Gavin TP, Hickner RC, Coffman TM, Somlyo AV, Yan Z, Haystead TAJ. Deletion of the protein kinase A/protein kinase G target SMTNL1 promotes an exercise-adapted phenotype in vascular smooth muscle. J Biol Chem 2008; 283:11850-9. [PMID: 18310078 DOI: 10.1074/jbc.m708628200] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
In vivo protein kinases A and G (PKA and PKG) coordinately phosphorylate a broad range of substrates to mediate their various physiological effects. The functions of many of these substrates have yet to be defined genetically. Herein we show a role for smoothelin-like protein 1 (SMTNL1), a novel in vivo target of PKG/PKA, in mediating vascular adaptations to exercise. Aortas from smtnl1(-/-) mice exhibited strikingly enhanced vasorelaxation before exercise, similar in extent to that achieved after endurance training of wild-type littermates. Additionally, contractile responses to alpha-adrenergic agonists were greatly attenuated. Immunological studies showed SMTNL1 is expressed in smooth muscle and type 2a striated muscle fibers. Consistent with a role in adaptations to exercise, smtnl1(-/-) mice also exhibited increased type 2a fibers before training and better performance after forced endurance training compared smtnl1(+/+) mice. Furthermore, exercise was found to reduce expression of SMTNL1, particularly in female mice. In both muscle types, SMTNL1 is phosphorylated at Ser-301 in response to adrenergic signals. In vitro SMTNL1 suppresses myosin phosphatase activity through a substrate-directed effect, which is relieved by Ser-301 phosphorylation. Our findings suggest roles for SMTNL1 in cGMP/cAMP-mediated adaptations to exercise through mechanisms involving direct modulation of contractile activity.
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Gavin TP, Drew JL, Kubik CJ, Pofahl WE, Hickner RC. Acute resistance exercise increases skeletal muscle angiogenic growth factor expression. Acta Physiol (Oxf) 2007; 191:139-46. [PMID: 17565567 DOI: 10.1111/j.1748-1716.2007.01723.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIMS Both aerobic and resistance exercise training promote skeletal muscle angiogenesis. Acute aerobic exercise increases several pro-angiogenic pathways, the best characterized being increases in vascular endothelial growth factor (VEGF). We hypothesized that acute resistance exercise also increases skeletal muscle angiogenic growth factor [VEGF and angiopoietin (Ang)] expression. METHODS Seven young, sedentary individuals had vastus lateralis muscle biopsies and blood drawn prior to and at 0, 2 and 4 h post-resistance exercise for the measurement of VEGF; VEGF receptor [KDR, Flt-1 and neuropilin 1 (Nrp1)]; Ang1 and Ang2; and the angiopoietin receptor--Tie2 expression. Resistance exercise consisted of progressive knee extensor (KE) exercise to determine one repetition maximum (1-RM) followed by three sets of 10 repetitions (3 x 10) of KE exercise at 60-80% of 1-RM. RESULTS Resistance exercise significantly increased skeletal muscle VEGF mRNA and protein and plasma VEGF protein at 2 and 4 h. Resistance exercise increased KDR mRNA and Tie2 mRNA at 4 h and Nrp1 mRNA at 2 and 4 h. Skeletal muscle Flt-1, Ang1, Ang2 and Ang2/Ang1 ratio mRNA were not altered by resistance exercise. CONCLUSIONS These findings suggest that acute resistance exercise increases skeletal muscle VEGF, VEGF receptor and angiopoietin receptor expression. The increases in muscle angiogenic growth factor expression in response to acute resistance exercise are similar in timing and magnitude with responses to acute aerobic exercise and are consistent with resistance exercise promoting muscle angiogenesis.
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MESH Headings
- Adult
- Analysis of Variance
- Angiopoietin-1/genetics
- Angiopoietin-1/metabolism
- Angiopoietin-2/genetics
- Angiopoietin-2/metabolism
- Capillaries
- Gene Expression
- Humans
- Leg/blood supply
- Male
- Muscle, Skeletal/chemistry
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/physiology
- Neovascularization, Physiologic
- Neuropilin-1/genetics
- Neuropilin-1/metabolism
- Physical Exertion/physiology
- Receptor, TIE-2/analysis
- Receptor, TIE-2/genetics
- Receptor, TIE-2/metabolism
- Receptors, Vascular Endothelial Growth Factor/analysis
- Receptors, Vascular Endothelial Growth Factor/genetics
- Receptors, Vascular Endothelial Growth Factor/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Vascular Endothelial Growth Factor A/analysis
- Vascular Endothelial Growth Factor A/genetics
- Vascular Endothelial Growth Factor A/metabolism
- Vascular Endothelial Growth Factor Receptor-1/genetics
- Vascular Endothelial Growth Factor Receptor-1/metabolism
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Focht BC, Knapp DJ, Gavin TP, Raedeke TD, Hickner RC. Affective and self-efficacy responses to acute aerobic exercise in sedentary older and younger adults. J Aging Phys Act 2007; 15:123-38. [PMID: 17556780 DOI: 10.1123/japa.15.2.123] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
This study examined the psychological responses to an acute bout of aerobic exercise in sedentary older and younger adults. Eighteen young (mean age 24 years) and 15 older adults (mean age 64 years) completed a 20-min bout of stationary cycling at 65% of VO2peak. Affective responses were assessed before, during, and immediately after exercise. Participants'exercise self-efficacy beliefs were assessed before and immediately after exercise. Both groups reported reduced pleasant feeling states and self-efficacy and increased physical exhaustion in response to acute exercise. Older adults also demonstrated a significant decrease in revitalization during and after cycling. Correlation analyses revealed that self-efficacy was related to feelings of fatigue during exercise and postexercise feelings of energy and fatigue. Both groups reported negative shifts in affect and self-efficacy during and 5 min after cycling.Acute affective and self-efficacy responses might influence one's motivation to adopt and maintain regular physical activity. The relationship between these acute responses and physical activity behavior across the life span warrants future inquiry.
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Gavin TP, Ruster RS, Carrithers JA, Zwetsloot KA, Kraus RM, Evans CA, Knapp DJ, Drew JL, McCartney JS, Garry JP, Hickner RC. No difference in the skeletal muscle angiogenic response to aerobic exercise training between young and aged men. J Physiol 2007; 585:231-9. [PMID: 17884919 PMCID: PMC2375453 DOI: 10.1113/jphysiol.2007.143198] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Ischaemia-induced skeletal muscle angiogenesis is impaired in aged compared with young mice. In humans, vascular endothelial growth factor (VEGF) mRNA and protein following an acute exercise bout are lower in aged compared with young untrained men. We hypothesized that exercise-induced skeletal muscle angiogenesis would be attenuated in aged compared with young men. In eight aged (mean age: 64 years) and six young (mean age: 25 years) sedentary men, muscle biopsies were obtained from the vastus lateralis prior to (Pre), after 1 week and after 8 weeks of an aerobic exercise training program for the measurement of capillarization and VEGF mRNA. Dialysate VEGF protein collected from the muscle interstitial space was measured at rest and during submaximal exercise at Pre, 1 week and 8 weeks. Exercise training increased capillary contacts (CC) and capillary-to-fibre perimeter exchange index (CFPE) of type I and IIA fibres similarly in young and aged. The CC of type IIA and IIB fibres was lower in aged compared with young independent of training status. Exercise-induced interstitial VEGF protein was lower in aged compared with young independent of training status. In untrained, greater exercise-induced interstitial VEGF protein during exercise was associated with greater type I, IIA and IIB CC. Exercise training increased VEGF mRNA similarly in young and aged. These results demonstrate that the angiogenic response to aerobic exercise training is not altered during the ageing process in humans. In addition, muscular activity-associated increases in interstitial VEGF protein may play an important role in the maintenance of skeletal muscle capillarization across the life span.
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Davanzo MJ, Jensen EB, Dohm GL, Bassel‐Duby R, Gavin TP. Overexpression of calcineurin increases skeletal muscle capillarization. FASEB J 2007. [DOI: 10.1096/fasebj.21.6.a1302-b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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57
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Gavin TP, Drew JL, Kubik CJ, Pofahl WE, Hickner RC. Acute resistance exercise increases skeletal muscle angiogenic growth factor expression. FASEB J 2007. [DOI: 10.1096/fasebj.21.6.a1302-c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Olfert IM, Breen EC, Gavin TP, Wagner PD. Temporal thrombospondin-1 mRNA response in skeletal muscle exposed to acute and chronic exercise. Growth Factors 2006; 24:253-9. [PMID: 17381066 DOI: 10.1080/08977190601000111] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Thrombospondin-l (TSP-1) is believed to be an endogenous angiogenic inhibitor. In this study, we report that a single 1 h bout of treadmill running increases TSP-1 mRNA 3-4-fold (p < 0.001). Interestingly, with short-term training (up to 5 days, 1 h/day) the acute response of TSP-1 mRNA to exercise was ablated after 3 days. Following long-term training (8 weeks, 1 h/day, 5 d/wk), in either normoxia or chronic hypoxia, the TSP-1 mRNA response to an acute bout of exercise was restored and increased 3-4-fold (p < 0.01). However, chronic exposure to hypoxia (8-weeks) decreases both the basal and acute exercise-induced TSP-1 mRNA levels by 44 and 48%, respectively (p < 0.05). Based on the robust TSP-1 gene response to a single acute exercise bout, its temporal response to repetitive exercise bouts, and the putative role of TSP-1 in the angiogenic process, we speculate that TSP-1 may play a role in regulating the onset of skeletal muscle angiogenesis in response to exercise.
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Kraus RM, Carrithers JA, Gavin TP, Ruster RS, Knapp DJ, Evans CA, Garry JP, Hickner RC. Resting Microvascular Exchange is Increased After 7-days of Exercise Training in Young and Older, Men and Women. Med Sci Sports Exerc 2006. [DOI: 10.1249/00005768-200611001-00006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Gavin TP, Westerkamp LM, Zwetsloot KA. Soleus, plantaris and gastrocnemius VEGF mRNA responses to hypoxia and exercise are preserved in aged compared with young female C57BL/6 mice. Acta Physiol (Oxf) 2006; 188:113-21. [PMID: 16948798 DOI: 10.1111/j.1748-1716.2006.01609.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
AIMS In humans, skeletal muscle capillarization and the vascular endothelial growth factor (VEGF) mRNA response to acute exercise are lower in aged compared with young. The exercise-induced increase in VEGF mRNA has been proposed to involve hypoxic regulation of VEGF and is believed to be fibre type-dependent. We hypothesized that attenuated VEGF mRNA responses to hypoxia and exercise with advanced age would be greatest in oxidative vs. glycolytic muscles. METHODS 3- and 24-month-old female C57BL/6 mice were exposed to acute hypoxia (FI O2 = 0.06) or performed a single exercise (65% of maximum treadmill running speed) bout. Capillarization and VEGF mRNA were analysed in the soleus, plantaris and gastrocnemius muscles. RESULTS In each muscle, VEGF mRNA was greater in aged compared with young, while the VEGF mRNA response to acute hypoxia or acute exercise was similar between young and aged. Morphological analysis revealed that type IIA fibre percentage and type IIB capillarization in the plantaris were greater and type IIB fibre cross-sectional area (FCSA) in the gastrocnemius was smaller in aged compared with young. CONCLUSIONS These findings suggest that ageing does not impair the potential for non-pathological angiogenesis in mice and that acute exercise increases VEGF mRNA in the soleus, plantaris and gastrocnemius muscles, which differ considerably in fibre type percentage.
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Gavin TP. Role of Capillaries in Regulating Skeletal Muscle Fiber Size. Med Sci Sports Exerc 2006. [DOI: 10.1249/00005768-200605001-00763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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62
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Gavin TP. Introduction and Overview. Med Sci Sports Exerc 2006. [DOI: 10.1249/00005768-200605001-00760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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63
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Zwetsloot KA, Westerkamp LM, Gavin TP. AMPK regulates skeletal muscle capillarization and VEGF mRNA. FASEB J 2006. [DOI: 10.1096/fasebj.20.4.a388-d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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64
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Gavin TP, Lust RM, Britton SL, Koch LG, Gordon SE. Overload‐induced skeletal muscle hypertrophy is not different in rats selectively bred for high and low endurance exercise capacity. FASEB J 2006. [DOI: 10.1096/fasebj.20.4.a807-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Ryan NA, Zwetsloot KA, Westerkamp LM, Hickner RC, Pofahl WE, Gavin TP. Lower skeletal muscle capillarization and VEGF expression in aged vs. young men. J Appl Physiol (1985) 2006; 100:178-85. [PMID: 16166239 DOI: 10.1152/japplphysiol.00827.2005] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Recently, we observed that muscle capillarization, vascular endothelial growth factor (VEGF) protein, and the VEGF mRNA response to acute exercise were lower in aged compared with young women (Croley AN, Zwetsloot KA, Westerkamp LM, Ryan NA, Pendergast aged men, Hickner RC, Pofahl WE, and Gavin TP. J Appl Physiol 99: 1875–1882, 2005). We hypothesized that similar age-related differences in muscle capillarization and VEGF expression would exist between young and aged men. Skeletal muscle biopsies were obtained from the vastus lateralis before and at 4 h after a submaximal exercise bout for the measurement of morphometry, capillarization, VEGF, KDR, and Flt-1 in seven aged (mean age 65 yr) and eight young (mean age 21 yr) sedentary men. In aged compared with young men, muscle capillary contacts and capillary-to-fiber perimeter exchange index were lower regardless of fiber type. Muscle VEGF mRNA and protein were lower in aged men both at rest and 4 h postexercise. Exercise increased muscle VEGF mRNA and protein and KDR mRNA independent of age group. There were no effects of exercise or age on muscle Flt-1 mRNA or protein or KDR protein. These results confirm that skeletal muscle capillarization and VEGF expression are lower in aged compared with young men.
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Croley AN, Zwetsloot KA, Westerkamp LM, Ryan NA, Pendergast AM, Hickner RC, Pofahl WE, Gavin TP. Lower capillarization, VEGF protein, and VEGF mRNA response to acute exercise in the vastus lateralis muscle of aged vs. young women. J Appl Physiol (1985) 2005; 99:1872-9. [PMID: 16024519 DOI: 10.1152/japplphysiol.00498.2005] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In humans, the majority of studies demonstrate an age-associated reduction in the number of capillaries surrounding skeletal muscle fibers; however, recent reports in rats suggest that muscle capillarization is well maintained with advanced age. In sedentary and trained men, aging lowers the number of capillaries surrounding type II, but not type I, skeletal muscle fibers. The fiber type-specific effect of aging on muscle capillarization is unknown in women. Vascular endothelial growth factor (VEGF) is important in the basal maintenance of skeletal muscle capillarization, and lower VEGF expression is associated with increased age in nonskeletal muscle tissue of women. Compared with young women (YW), we hypothesized that aged women (AW) would demonstrate 1) lower muscle capillarization in a fiber type-specific manner and 2) lower VEGF and VEGF receptor expression at rest and in response to acute exercise. Nine sedentary AW (70 + 8 yr) and 11 YW (22 + 3 yr) had vastus lateralis muscle biopsies obtained before and at 4 h after a submaximal exercise bout for the measurement of morphometry and VEGF and VEGF receptor expression. In AW compared with YW, muscle capillary contacts were lower overall (YW: 2.36 + 0.32 capillaries; AW: 2.08 + 0.17 capillaries), specifically in type II (YW: 2.37 + 0.39 capillaries; AW: 1.91 + 0.36 capillaries) but not type I fibers (YW: 2.36 + 0.34 capillaries; AW: 2.26 + 0.24 capillaries). Muscle VEGF protein was 35% lower at rest, and the exercise-induced increase in VEGF mRNA was 50% lower in AW compared with YW. There was no effect of age on VEGF receptor expression. These results provide evidence that, in the vastus lateralis of women, 1) capillarization surrounding type II muscle fibers is lower in AW compared with YW and 2) resting VEGF protein and the VEGF mRNA response to exercise are lower in AW compared with YW.
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Zwetsloot KA, Hickner RC, Ruster RS, Carrithers JA, Kraus RM, Evans CA, Knapp DJ, Drew JL, McCartney JS, Gavin TP. VEGF mRNA Expression In Young And Aged Skeletal Muscle With 7 Days And 8 Weeks Of Endurance Exercise Training. Med Sci Sports Exerc 2005. [DOI: 10.1249/00005768-200505001-02011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Ruster RS, Hickner RC, Carrithers JA, Kraus RM, Evans CA, Knapp DJ, Drew JL, McCartney JS, Gavin TP. Effect Of 7 Days Of Exercise Training On Interstitial VEGF Protein In Young And Aged Skeletal Muscle. Med Sci Sports Exerc 2005. [DOI: 10.1249/00005768-200505001-00833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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69
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George SC, Hickner RC, Gavin TP, Westerkamp CM, Westerkamp LM, Gordon SE. Effect of L-NAME Administration on Angiogenesis in Overloaded, Hypertrophying Rat Skeletal Muscle. Med Sci Sports Exerc 2005. [DOI: 10.1249/00005768-200505001-02012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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70
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Kraus RM, Evans CA, Carrithers JA, Carrithers HM, Ruster RS, Knapp DJ, Drew JL, Gavin TP, Hickner RC. Microvascular Exchange Response To Local Norepinephrine Administration Is Increased After 7-days Of Exercise Training In Elderly Men. Med Sci Sports Exerc 2005. [DOI: 10.1249/00005768-200505001-01893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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71
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Gavin TP, Ryan NA, Zwetsloot KA, Westerkamp LM, Pofahl WE, Hickner RC. Skeletal Muscle VEGF mRNA is Lower in Aged Men. Med Sci Sports Exerc 2005. [DOI: 10.1249/00005768-200505001-00834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Gavin TP, Stallings HW, Zwetsloot KA, Westerkamp LM, Ryan NA, Moore RA, Pofahl WE, Hickner RC. Lower capillary density but no difference in VEGF expression in obese vs. lean young skeletal muscle in humans. J Appl Physiol (1985) 2005; 98:315-21. [PMID: 15298982 DOI: 10.1152/japplphysiol.00353.2004] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Obesity is associated with lower skeletal muscle capillarization and lower insulin sensitivity. Vascular endothelial growth factor (VEGF) is important for the maintenance of the skeletal muscle capillaries. To investigate whether VEGF and VEGF receptor [kinase insert domain-containing receptor (KDR) and Flt-1] expression are lower with obesity, vastus lateralis muscle biopsies were obtained from eight obese and eight lean young sedentary men before and 2 h after a 1-h submaximal aerobic exercise bout for the measurement of VEGF, KDR, Flt-1, and skeletal muscle fiber and capillary characteristics. There were no differences in VEGF or VEGF receptor mRNA at rest between lean and obese muscle. Exercise increased VEGF (10-fold), KDR (3-fold), and Flt-1 (5-fold) mRNA independent of group. There were no differences in VEGF, KDR, or Flt-1 protein between groups. Compared with lean skeletal muscle, the number of capillary contacts per fiber was the same, but lower capillary density (CD), greater muscle cross sectional area, and lower capillary-to-fiber area ratio were observed in both type I and II fibers in obese muscle. Multiple linear regression revealed that 49% of the variance in insulin sensitivity (homeostasis model assessment) could be explained by percentage of body fat (35%) and maximal oxygen uptake per kilogram of fat-free mass (14%). Linear regression revealed significant relationships between maximal oxygen uptake and both CD and capillary-to-fiber perimeter exchange. Although differences may exist in CD and capillary-to-fiber area ratio between lean and obese skeletal muscle, the present results provide evidence that VEGF and VEGF receptor expression are not different between lean and obese muscle.
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Gavin TP, Stallings HW, Zwetsloot KA, Westerkamp LM, Pofahl WE, Hickner RC. VEGF andVEGF Receptor Expression Are Not Altered In Obese Skeletal Muscle. Med Sci Sports Exerc 2004. [DOI: 10.1249/00005768-200405001-01291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Kraus RM, Stallings HW, Yeager RC, Gavin TP. Circulating plasma VEGF response to exercise in sedentary and endurance-trained men. J Appl Physiol (1985) 2004; 96:1445-50. [PMID: 14660505 DOI: 10.1152/japplphysiol.01031.2003] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The skeletal muscle capillary supply is an important determinant of maximum exercise capacity, and it is well known that endurance exercise training increases the muscle capillary supply. The muscle capillary supply and exercise-induced angiogenesis are regulated in part by vascular endothelial growth factor (VEGF). VEGF is produced by skeletal muscle cells and can be secreted into the circulation. We investigated whether there are differences in circulating plasma VEGF between sedentary individuals (Sed) and well-trained endurance athletes (ET) at rest or in response to acute exercise. Eight ET men (maximal oxygen consumption: 63.8 ± 2.3 ml·kg-1·min-1; maximum power output: 409.4 ± 13.3 W) and eight Sed men (maximal oxygen consumption: 36.3 ± 2.1 ml·kg-1·min-1; maximum power output: 234.4 ± 13.3 W) exercised for 1 h at 50% of maximum power output. Antecubital vein plasma was collected at rest and at 0, 2, and 4 h postexercise. Plasma VEGF was measured by ELISA analysis. Acute exercise significantly increased VEGF at 0 and 2 h postexercise in ET subjects but did not increase VEGF at any time point in Sed individuals. There was no difference in VEGF between ET and Sed subjects at any time point. When individual peak postexercise VEGF was analyzed, exercise did increase VEGF independent of training status. In conclusion, exercise can increase plasma VEGF in both ET athletes and Sed men; however, there is considerable variation in the individual time of the peak VEGF response.
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Richardson RS, Leek BT, Gavin TP, Haseler LJ, Mudaliar SRD, Henry R, Mathieu-Costello O, Wagner PD. Reduced Mechanical Efficiency in Chronic Obstructive Pulmonary Disease but Normal Peak V̇o2with Small Muscle Mass Exercise. Am J Respir Crit Care Med 2004; 169:89-96. [PMID: 14500263 DOI: 10.1164/rccm.200305-627oc] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
We studied six patients with chronic obstructive pulmonary disease (COPD) (FEV1 = 1.1 +/- 0.2 L, 32% of predicted) and six age- and activity level-matched control subjects while performing both maximal bicycle exercise and single leg knee-extensor exercise. Arterial and femoral venous blood sampling, thermodilution blood flow measurements, and needle biopsies allowed the assessment of muscle oxygen supply, utilization, and structure. Maximal work rates and single leg VO2max (control subjects = 0.63 +/- 0.1; patients with COPD = 0.37 +/- 0.1 L/minute) were significantly greater in the control group during bicycle exercise. During knee-extensor exercise this difference in VO2max disappeared, whereas maximal work capacity was reduced (flywheel resistance: control subjects = 923 +/- 198; patients with COPD = 612 +/- 81 g) revealing a significantly reduced mechanical efficiency (work per unit oxygen consumed) with COPD. The patients had an elevated number of less efficient type II muscle fibers, whereas muscle fiber cross-sectional areas, capillarity, and mitochondrial volume density were not different between the groups. Therefore, although metabolic capacity per se is unchanged, fiber type differences associated with COPD may account for the reduced muscular mechanical efficiency that becomes clearly apparent during knee-extensor exercise, when muscle function is no longer overshadowed by the decrement in lung function.
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Gavin TP, Robinson CB, Yeager RC, England JA, Nifong LW, Hickner RC. Angiogenic growth factor response to acute systemic exercise in human skeletal muscle. J Appl Physiol (1985) 2004; 96:19-24. [PMID: 12949011 DOI: 10.1152/japplphysiol.00748.2003] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We investigated whether acute systemic exercise increases vascular endothelial growth factor (VEGF), VEGF receptor (KDR and Flt-1) mRNA, and VEGF protein in sedentary humans. Twelve sedentary subjects were recruited and performed 1 h of acute, cycle ergometer exercise at 50% of maximal oxygen consumption. Muscle biopsies were obtained from the vastus lateralis before exercise and at 0, 2, and 4 h postexercise. Acute exercise significantly increased VEGF mRNA at 2 and 4 h and increased KDR and Flt-1 mRNA at 4 h postexercise. The sustained increase in VEGF mRNA through 4 h and the increases in KDR and Flt-1 at 4 h are different from their respective time course responses in rats. In contrast to the increase in VEGF mRNA postexercise, VEGF protein levels were decreased at 0 h postexercise. These results provide evidence in humans that 1) VEGF, KDR, and Flt-1 mRNA are increased by acute systemic exercise; 2) the time course of the VEGF, KDR, and Flt-1 mRNA responses are different from those previously reported in rats (Gavin TP and Wagner PD. Acta Physiol Scand 175: 201-209, 2002); and 3) VEGF protein is decreased immediately after exercise.
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Abstract
Exercise increases heat production. During exercise in both warm and cold conditions, the major dilemma is the dissipation of the heat produced from muscular activity. The use of clothing generally represents a layer of insulation and as such imposes a barrier to heat transfer and evaporation from the skin surface. In warm environments, additional clothing increases thermal insulation causing more rapid increases in temperature during exercise and imposes a barrier to sweat evaporation. However, clothing can serve a protective function by reducing radiant heat gain and thermal stress. Recent research suggests that neither the inclusion of modest amounts of clothing nor the clothing fabric alter thermoregulation or thermal comfort during exercise in warm conditions. In the cold, most reports do not support an effect of clothing fabric on thermoregulation; however, there are reports demonstrating an effect. Clothing construction does alter thermoregulation during and following exercise in the cold, where fishnet construction offers greater heat dissipation. Future research should include conditions that more closely mimic outdoor conditions, where high work rates, large airflow and high relative humidity can significantly impact thermoregulation.
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Gavin TP, Wagner PD. Attenuation of the exercise-induced increase in skeletal muscle Flt-1 mRNA by nitric oxide synthase inhibition. ACTA PHYSIOLOGICA SCANDINAVICA 2002; 175:201-9. [PMID: 12100359 DOI: 10.1046/j.1365-201x.2002.00987.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
UNLABELLED We investigated the vascular endothelial growth factor (VEGF) receptor [fms-like-tyrosine kinase (Flt-1 and fetal liver kinase-1 (Flk-1)] response to acute exercise. In female Wistar rats, the VEGF receptor messenger RNA (mRNA) response to a single acute exercise bout was examined using semi-quantitative Northern blot from the left gastrocnemius muscles at rest and post-exercise at 0, 1, 2, 4, 8, 16, 24 and 48 h. Exercise altered both Flt-1 and Flk-1 mRNA, with significant increases in Flt-1 mRNA at 1 and 24 h. However, post-hoc analysis was unable to discern the time point where a significant increase in Flk-1 mRNA occurred. To investigate the regulation of Flt-1 mRNA by exercise we examined if nitric oxide synthase (NOS) inhibition alters the Flt-1 mRNA response. Eight groups [ CONDITION Rest or Exercise; Drug: Saline, 30 mg kg(-1)N(omega)-nitro-L-arginine methyl ester (L-NAME), 300 mg kg(-1) L-NAME or 300 mg kg(-1) D-NAME] were used to determine the effect of NOS inhibition on the Flt-1 mRNA response to exercise. L-NAME, a known NOS inhibitor, attenuated the exercise-induced increase in Flt-1 mRNA by approximately 50%. These findings suggest that: (1) exercise alters Flt-1 and Flk-1 gene expression; and (2) NO is important in the regulation of the Flt-1 gene response to exercise.
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Brutsaert TD, Gavin TP, Fu Z, Breen EC, Tang K, Mathieu-Costello O, Wagner PD. Regional differences in expression of VEGF mRNA in rat gastrocnemius following 1 hr exercise or electrical stimulation. BMC PHYSIOLOGY 2002; 2:8. [PMID: 12086595 PMCID: PMC117122 DOI: 10.1186/1472-6793-2-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2002] [Accepted: 06/19/2002] [Indexed: 01/02/2023]
Abstract
BACKGROUND Vascular endothelial growth factor (VEGF) mRNA levels increase in rat skeletal muscle after a single bout of acute exercise. We assessed regional differences in VEGF165 mRNA levels in rat gastrocnemius muscle using in situ hybridization after inducing upregulation of VEGF by treadmill running (1 hr) or electrical stimulation (1 hr). Muscle functional regions were defined as oxidative (primarily oxidative fibers, I and IIa), or glycolytic (entirely IIb or IId/x fibers). Functional regions were visualized on muscle cross sections that were matched in series to slides processed through in situ hybridization with a VEGF165 probe. A greater upregulation in oxidative regions was hypothesized. RESULTS Total muscle VEGF mRNA (via Northern blot) was upregulated 3.5-fold with both exercise and with electrical stimulation (P = 0.015). Quantitative densitometry of the VEGF mRNA signal via in situ hybridization reveals significant regional differences (P <or= 0.01) and protocol differences (treadmill, electrical stimulation, and control, P <or= 0.05). Mean VEGF mRNA signal was higher in the oxidative region in both treadmill run (approximately 7%, N = 4 muscles, P <or= 0.05) and electrically stimulated muscles (approximately 60%, N = 4, P <or= 0.05). These regional differences were not significantly different from control muscle (non-exercised, non-stimulated, N = 2 muscles), although nearly so for electrically stimulated muscle (P = 0.056). CONCLUSIONS Moderately higher VEGF mRNA signal in oxidative muscle regions is consistent with regional differences in capillary density. However, it is not possible to determine if the VEGF mRNA signal difference is important in either the maintenance of regional capillarity differences or exercise induced angiogenesis.
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MESH Headings
- Animals
- Blotting, Northern/methods
- Electric Stimulation/methods
- Female
- Gene Expression Regulation/physiology
- Muscle Fibers, Fast-Twitch/chemistry
- Muscle Fibers, Fast-Twitch/physiology
- Muscle Fibers, Slow-Twitch/chemistry
- Muscle Fibers, Slow-Twitch/physiology
- Muscle, Skeletal/chemistry
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/physiology
- Physical Conditioning, Animal/physiology
- RNA, Messenger/biosynthesis
- Rats
- Rats, Wistar
- Time Factors
- Up-Regulation/physiology
- Vascular Endothelial Growth Factor A/biosynthesis
- Vascular Endothelial Growth Factor A/genetics
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Gavin TP, Wagner PD. Acute ethanol increases angiogenic growth factor gene expression in rat skeletal muscle. J Appl Physiol (1985) 2002; 92:1176-82. [PMID: 11842056 DOI: 10.1152/japplphysiol.00929.2001] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Moderate ethanol consumption demonstrates a protective effect against cardiovascular disease and improves insulin sensitivity, possibly through angiogenesis. We investigated whether 1) ethanol would increase skeletal muscle growth factor gene expression and 2) the effects of ethanol on skeletal muscle growth factor gene expression were independent of exercise-induced growth factor gene expression. Female Wistar rats were used. Four groups (saline + rest; saline + exercise; 17 mmol/kg ethanol + rest; and 17 mmol/kg ethanol + exercise) were used to measure the growth factor response to acute exercise and ethanol administration. Vascular endothelial growth factor (VEGF), transforming growth factor-beta(1) (TGF-beta(1)), basic fibroblast growth factor (bFGF), Flt-1, and Flk-1 mRNA were analyzed from the left gastrocnemius by quantitative Northern blot. Ethanol increased VEGF, TGF-beta(1), bFGF, and Flt-1 mRNA at rest and after acute exercise. Ethanol increased resting Flk-1 mRNA. Ethanol increased bFGF mRNA independently of exercise. These findings suggest that 1) ethanol can increase skeletal muscle angiogenic growth factor gene expression and 2) the mechanisms responsible for the ethanol-induced increases in VEGF, TGF-beta(1), and Flt-1 mRNA appear to be different from those responsible for exercise-induced regulation. Therefore, these results provide evidence in adult rat tissue that the protective cardiovascular effects of moderate ethanol consumption may result in part through the increase of angiogenic growth factors.
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Gavin TP, Babington JP, Harms CA, Ardelt ME, Tanner DA, Stager JM. Clothing fabric does not affect thermoregulation during exercise in moderate heat. Med Sci Sports Exerc 2001; 33:2124-30. [PMID: 11740309 DOI: 10.1097/00005768-200112000-00023] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE We investigated whether temperature regulation is improved during exercise in moderate heat by the use of clothing constructed from fabric that was purported to promote sweat evaporation compared with traditional fabrics. METHODS Eight well-trained, euhydrated males performed three exercise bouts wearing garments made from an evaporative polyester fabric (SYN), wearing garments made from traditional cotton fabric (COT), or dressed seminude (S-N) in random order. Bouts consisted of 15 min seated rest, 30 min running at 70% .VO(2max), 15 min walking at 40% .VO(2max), and 15 min seated rest, all at 30 +/- 1 degrees C and 35 +/- 5% relative humidity. COT and SYN clothing ensembles consisted of crew neck, short sleeve T-shirts, cycling shorts, and anklet socks made from their respective materials, and running shoes. The S-N condition consisted of a Lycra swim suit, polyester socks, and running shoes. RESULTS Mean skin temperature was lower for S-N during preexercise rest when compared with SYN and COT. No differences in mean body temperature, rectal temperature, or mean skin temperature were observed during or after exercise. No differences in VO2 or heart rate were observed. No differences in comfort sensations were observed. CONCLUSION In summary, before, during, or after exercise in a moderately warm environmental condition, neither the addition of a modest amount of clothing nor the fabric characteristics of this clothing alters physiological, thermoregulatory, or comfort sensation responses.
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Gavin TP, Wagner PD. Effect of short-term exercise training on angiogenic growth factor gene responses in rats. J Appl Physiol (1985) 2001; 90:1219-26. [PMID: 11247917 DOI: 10.1152/jappl.2001.90.4.1219] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We investigated whether 1) 5 days of exercise training would reduce the acute exercise-induced increase in skeletal muscle growth factor gene expression; and 2) reductions in the increase in growth factor gene expression in response to short-term exercise training would be coincident with increases in skeletal muscle oxidative potential. Female Wistar rats were used. Six groups (rest; exercise for 1-5 consecutive days) were used to measure the growth factor response through the early phases of an exercise training program. Vascular endothelial growth factor (VEGF), transforming growth factor-beta1 (TGF-beta1), and basic fibroblast growth factor (bFGF) mRNA were analyzed from the left gastrocnemius by quantitative Northern blot. Citrate synthase activity was analyzed from the right gastrocnemius. VEGF and TGF-beta1 mRNA increased after each of 5 days of exercise training, whereas exercise on any day did not increase bFGF mRNA. On day 1, the VEGF mRNA response was significantly greater than on days 2-5. However, the reduced increase in VEGF mRNA observed on days 2-5 was not coincident with increases in citrate synthase activity. These findings suggest that, in skeletal muscle, 1) VEGF and TGF-beta1 mRNA are increased through 5 days of exercise training and 2) the reduced exercise-induced increase in VEGF mRNA responses on days 2-5 does not result from increases in oxidative potential.
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Hopkins SR, Barker RC, Brutsaert TD, Gavin TP, Entin P, Olfert IM, Veisel S, Wagner PD. Pulmonary gas exchange during exercise in women: effects of exercise type and work increment. J Appl Physiol (1985) 2000; 89:721-30. [PMID: 10926659 DOI: 10.1152/jappl.2000.89.2.721] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Exercise-induced arterial hypoxemia (EIAH) has been reported in male athletes, particularly during fast-increment treadmill exercise protocols. Recent reports suggest a higher incidence in women. We hypothesized that 1-min incremental (fast) running (R) protocols would result in a lower arterial PO(2) (Pa(O(2))) than 5-min increment protocols (slow) or cycling exercise (C) and that women would experience greater EIAH than previously reported for men. Arterial blood gases, cardiac output, and metabolic data were obtained in 17 active women [mean maximal O(2) uptake (VO(2 max)) = 51 ml. kg(-1). min(-1)]. They were studied in random order (C or R), with a fast VO(2 max) protocol. After recovery, the women performed 5 min of exercise at 30, 60, and 90% of VO(2 max) (slow). One week later, the other exercise mode (R or C) was similarly studied. There were no significant differences in VO(2 max) between R and C. Pulmonary gas exchange was similar at rest, 30%, and 60% of VO(2 max). At 90% of VO(2 max), Pa(O(2)) was lower during R (mean +/- SE = 94 +/- 2 Torr) than during C (105 +/- 2 Torr, P < 0.0001), as was ventilation (85.2 +/- 3.8 vs. 98.2 +/- 4.4 l/min BTPS, P < 0.0001) and cardiac output (19.1 +/- 0.6 vs. 21.1 +/- 1.0 l/min, P < 0.001). Arterial PCO(2) (32.0 +/- 0.5 vs. 30.0 +/- 0.6 Torr, P < 0.001) and alveolar-arterial O(2) difference (A-aDO(2); 22 +/- 2 vs. 16 +/- 2 Torr, P < 0.0001) were greater during R. Pa(O(2)) and A-aDO(2) were similar between slow and fast. Nadir Pa(O(2)) was </=80 Torr in four women (24%) but only during fast-R. In all subjects, Pa(O(2)) at VO(2 max) was greater than the lower 95% prediction limit calculated from available data in men (n = 72 C and 38 R) for both R and C. These data suggest intrinsic differences in gas exchange between R and C, due to differences in ventilation and also efficiency of gas exchange. The Pa(O(2)) responses to R and C exercise in our 17 subjects do not differ significantly from those previously observed in men.
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Gavin TP, Spector DA, Wagner H, Breen EC, Wagner PD. Effect of captopril on skeletal muscle angiogenic growth factor responses to exercise. J Appl Physiol (1985) 2000; 88:1690-7. [PMID: 10797131 DOI: 10.1152/jappl.2000.88.5.1690] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Acute exercise increases vascular endothelial growth factor (VEGF), transforming growth factor-beta(1) (TGF-beta(1)), and basic fibroblast growth factor (bFGF) mRNA levels in skeletal muscle, with the greatest increase in VEGF mRNA. VEGF functions via binding to the VEGF receptors Flk-1 and Flt-1. Captopril, an angiotensin-converting enzyme inhibitor, has been suggested to reduce the microvasculature in resting and exercising skeletal muscle. However, the molecular mechanisms responsible for this reduction have not been investigated. We hypothesized that this might occur via reduced VEGF, TGF-beta(1), bFGF, Flk-1, and Flt-1 gene expression at rest and after exercise. To investigate this, 10-wk-old female Wistar rats were placed into four groups (n = 6 each): 1) saline + rest; 2) saline + exercise; 3) 100 mg/kg ip captopril + rest; and 4) 100 mg/kg ip captopril + exercise. Exercise consisted of 1 h of running at 20 m/min on a 10 degrees incline. VEGF, TGF-beta(1), bFGF, Flk-1, and Flt-1 mRNA were analyzed from the left gastrocnemius by quantitative Northern blot. Exercise increased VEGF mRNA 4.8-fold, TGF-beta(1) mRNA 1.6-fold, and Flt-1 mRNA 1.7-fold but did not alter bFGF or Flk-1 mRNA measured 1 h after exercise. Captopril did not affect the rest or exercise levels of VEGF, TGF-beta(1), bFGF, and Flt-1 mRNA. Captopril did reduce Flk-1 mRNA 30-40%, independently of exercise. This is partially consistent with the suggestion that captopril may inhibit capillary growth.
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85
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Gavin TP, Spector DA, Wagner H, Breen EC, Wagner PD. Nitric oxide synthase inhibition attenuates the skeletal muscle VEGF mRNA response to exercise. J Appl Physiol (1985) 2000; 88:1192-8. [PMID: 10749807 DOI: 10.1152/jappl.2000.88.4.1192] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and transforming growth factor-beta(1) (TGF-beta(1)) mRNA increase in rat skeletal muscle in response to a single acute exercise bout. Nitric oxide (NO) is released locally by muscle vascular endothelium and muscle fibers during exercise, contributes to the blood flow response to exercise, and regulates mitochondrial respiration. We hypothesized that a reduction in NO production, via NO synthase inhibition, would demonstrate a link between NO and the VEGF, bFGF, and TGF-beta(1) gene responses to exercise. To investigate this hypothesis, 9-wk-old female Wistar rats were divided into eight treatment groups (n = 6 each): 1) saline + rest, 2) saline + exercise, 3) 30 mg/kg N(omega)-nitro-L-arginine methyl ester (L-NAME, a known NOS inhibitor) + rest, 4) 30 mg/kg L-NAME + exercise, 5) 300 mg/kg L-NAME + rest, 6) 300 mg/kg L-NAME + exercise, 7) 300 mg/kg N(omega)-nitro-D-arginine methyl ester (D-NAME, inactive enantiomer of L-NAME) + rest, and 8) 300 mg/kg D-NAME + exercise. Exercise consisted of 1 h of running at 20 m/min on a 10 degrees incline. VEGF, TGF-beta(1), and bFGF mRNA from left gastrocnemius were analyzed by quantitative Northern blot. Submaximal exercise for 1 h increased VEGF mRNA 4.2-fold and TGF-beta(1) mRNA 1.5-fold in untreated rats but did not increase bFGF mRNA. The exercise-induced increase in VEGF mRNA was attenuated approximately 50% by 30 and 300 mg/kg L-NAME; the TGF-beta(1) mRNA increase was unaffected by 300 mg/kg L-NAME. In addition, 300 mg/kg D-NAME had no effect on the exercise-induced increase in VEGF mRNA. Administration of 300 mg/kg L-NAME had no effect on bFGF mRNA. These findings suggest that NO is important in the regulation of the VEGF gene response to exercise through increases in VEGF transcription or by increases in the VEGF mRNA half-life.
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Barker RC, Hopkins SR, Kellogg N, Olfert IM, Brutsaert TD, Gavin TP, Entin PL, Rice AJ, Wagner PD. Measurement of cardiac output during exercise by open-circuit acetylene uptake. J Appl Physiol (1985) 1999; 87:1506-12. [PMID: 10517785 DOI: 10.1152/jappl.1999.87.4.1506] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Noninvasive measurement of cardiac output (QT) is problematic during heavy exercise. We report a new approach that avoids unpleasant rebreathing and resultant changes in alveolar PO(2) or PCO(2) by measuring short-term acetylene (C(2)H(2)) uptake by an open-circuit technique, with application of mass balance for the calculation of QT. The method assumes that alveolar and arterial C(2)H(2) pressures are the same, and we account for C(2)H(2) recirculation by extrapolating end-tidal C(2)H(2) back to breath 1 of the maneuver. We correct for incomplete gas mixing by using He in the inspired mixture. The maneuver involves switching the subject to air containing trace amounts of C(2)H(2) and He; ventilation and pressures of He, C(2)H(2), and CO(2) are measured continuously (the latter by mass spectrometer) for 20-25 breaths. Data from three subjects for whom multiple Fick O(2) measurements of QT were available showed that measurement of QT by the Fick method and by the C(2)H(2) technique was statistically similar from rest to 90% of maximal O(2) consumption (VO(2 max)). Data from 12 active women and 12 elite male athletes at rest and 90% of VO(2 max) fell on a single linear relationship, with O(2) consumption (VO(2)) predicting QT values of 9.13, 15.9, 22.6, and 29.4 l/min at VO(2) of 1, 2, 3, and 4 l/min. Mixed venous PO(2) predicted from C(2)H(2)-determined QT, measured VO(2), and arterial O(2) concentration was approximately 20-25 Torr at 90% of VO(2 max) during air breathing and 10-15 Torr during 13% O(2) breathing. This modification of previous gas uptake methods, to avoid rebreathing, produces reasonable data from rest to heavy exercise in normal subjects.
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Gavin TP, Stager JM. The effect of exercise modality on exercise-induced hypoxemia. RESPIRATION PHYSIOLOGY 1999; 115:317-23. [PMID: 10424361 DOI: 10.1016/s0034-5687(99)00012-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
To investigate the effect of exercise mode on arterial oxyhemoglobin saturation (SaO2), 13 healthy, actively training men who displayed exercise-induced hypoxemia (EIH) performed two incremental maximal exercise tests: uphill treadmill running and cycle ergometry. At maximum, treadmill running resulted in a lower SaO2 (88.6+/-2% versus 92.6+/-2.0%) a lower ventilatory equivalent for carbon dioxide (VE/VCO2; 28.8+/-0.6 versus 31.2+/-0.9), and a higher maximal oxygen consumption (VO2, MAX; 4.83+/-0.11 l x min(-1) versus 4.61+/-0.14 l x min(-1) when compared to cycle ergometry. When data were combined from maximal running and cycling. SaO2 was correlated to VE/VCO2 (r = 0.54). However, there was no relationship between the differences in SaO2 and ventilation between exercise modes. This suggests that ventilation is important in the maintenance of SaO2, but that the difference observed in SaO2 between treadmill running and cycle ergometry cannot be explained by differences in ventilation and must be due to differences in diffusion limitation or ventilation-perfusion inequality.
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Richardson RS, Grassi B, Gavin TP, Haseler LJ, Tagore K, Roca J, Wagner PD. Evidence of O2 supply-dependent VO2 max in the exercise-trained human quadriceps. J Appl Physiol (1985) 1999; 86:1048-53. [PMID: 10066722 DOI: 10.1152/jappl.1999.86.3.1048] [Citation(s) in RCA: 177] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Maximal O2 delivery and O2 uptake (VO2) per 100 g of active muscle mass are far greater during knee extensor (KE) than during cycle exercise: 73 and 60 ml. min-1. 100 g-1 (2.4 kg of muscle) (R. S. Richardson, D. R. Knight, D. C. Poole, S. S. Kurdak, M. C. Hogan, B. Grassi, and P. D. Wagner. Am. J. Physiol. 268 (Heart Circ. Physiol. 37): H1453-H1461, 1995) and 28 and 25 ml. min-1. 100 g-1 (7.5 kg of muscle) (D. R. Knight, W. Schaffartzik, H. J. Guy, R. Predilleto, M. C. Hogan, and P. D. Wagner. J. Appl. Physiol. 75: 2586-2593, 1993), respectively. Although this is evidence of muscle O2 supply dependence in itself, it raises the following question: With such high O2 delivery in KE, are the quadriceps still O2 supply dependent at maximal exercise? To answer this question, seven trained subjects performed maximum KE exercise in hypoxia [0.12 inspired O2 fraction (FIO2)], normoxia (0.21 FIO2), and hyperoxia (1.0 FIO2) in a balanced order. The protocol (after warm-up) was a square wave to a previously determined maximum work rate followed by incremental stages to ensure that a true maximum was achieved under each condition. Direct measures of arterial and venous blood O2 concentration in combination with a thermodilution blood flow technique allowed the determination of O2 delivery and muscle VO2. Maximal O2 delivery increased with inspired O2: 1.3 +/- 0.1, 1.6 +/- 0.2, and 1.9 +/- 0.2 l/min at 0.12, 0.21, and 1.0 FIO2, respectively (P < 0.05). Maximal work rate was affected by variations in inspired O2 (-25 and +14% at 0.12 and 1.0 FIO2, respectively, compared with normoxia, P < 0.05) as was maximal VO2 (VO2 max): 1.04 +/- 0.13, 1. 24 +/- 0.16, and 1.45 +/- 0.19 l/min at 0.12, 0.21, and 1.0 FIO2, respectively (P < 0.05). Calculated mean capillary PO2 also varied with FIO2 (28.3 +/- 1.0, 34.8 +/- 2.0, and 40.7 +/- 1.9 Torr at 0.12, 0.21, and 1.0 FIO2, respectively, P < 0.05) and was proportionally related to changes in VO2 max, supporting our previous finding that a decrease in O2 supply will proportionately decrease muscle VO2 max. As even in the isolated quadriceps (where normoxic O2 delivery is the highest recorded in humans) an increase in O2 supply by hyperoxia allows the achievement of a greater VO2 max, we conclude that, in normoxic conditions of isolated KE exercise, KE VO2 max in trained subjects is not limited by mitochondrial metabolic rate but, rather, by O2 supply.
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Hopkins SR, Gavin TP, Siafakas NM, Haseler LJ, Olfert IM, Wagner H, Wagner PD. Effect of prolonged, heavy exercise on pulmonary gas exchange in athletes. J Appl Physiol (1985) 1998; 85:1523-32. [PMID: 9760350 DOI: 10.1152/jappl.1998.85.4.1523] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
During maximal exercise, ventilation-perfusion inequality increases, especially in athletes. The mechanism remains speculative. We hypothesized that, if interstitial pulmonary edema is involved, prolonged exercise would result in increasing ventilation-perfusion inequality over time by exposing the pulmonary vascular bed to high pressures for a long duration. The response to short-term exercise was first characterized in six male athletes [maximal O2 uptake (V(O2)max) = 63 ml x kg-1 x min-1] by using 5 min of cycling exercise at 30, 65, and 90% V(O2) max. Multiple inert-gas, blood-gas, hemodynamic, metabolic rate, and ventilatory data were obtained. Resting log SD of the perfusion distribution (log SDQ) was normal [0.50 +/- 0.03 (SE)] and increased with exercise (log SDQ = 0.65 +/- 0.04, P < 0.005), alveolar-arterial O2 difference increased (to 24 +/- 3 Torr), and end-capillary pulmonary diffusion limitation occurred at 90% V(O2)max. The subjects recovered for 30 min, then, after resting measurements were taken, exercised for 60 min at approximately 65% V(O2)max. O2 uptake, ventilation, cardiac output, and alveolar-arterial O2 difference were unchanged after the first 5 min of this test, but log SDQ increased from 0.59 +/- 0.03 at 5 min to 0. 66 +/- 0.05 at 60 min (P < 0.05), without pulmonary diffusion limitation. Log SDQ was negatively related to total lung capacity normalized for body surface area (r = -0.97, P < 0.005 at 60 min). These data are compatible with interstitial edema as a mechanism and suggest that lung size is an important determinant of the efficiency of gas exchange during exercise.
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Roca J, Gavin TP, Jordan M, Siafakas N, Wagner H, Benoit H, Breen E, Wagner PD. Angiogenic growth factor mRNA responses to passive and contraction-induced hyperperfusion in skeletal muscle. J Appl Physiol (1985) 1998; 85:1142-9. [PMID: 9729593 DOI: 10.1152/jappl.1998.85.3.1142] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
It has been proposed that, in skeletal muscle, the angiogenic response to exercise may be signaled by the increase in muscle blood flow, via biomechanical changes in the microcirculation (increased shear stress and/or wall tension). To examine this hypothesis, we compared the change in abundance of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and transforming growth factor-beta1 (TGF-beta1) mRNA in skeletal muscles of the canine leg after 1 h of pump-controlled high blood flow alone (passive hyperperfusion; protocol A) and electrical stimulation of the femoral and sciatic nerves producing muscle contraction (protocol B). The increase in leg blood flow (5.4- and 5. 9-fold change from resting values, respectively) was similar in both groups. Passive hyperperfusion alone did not increase message abundance for VEGF (ratio of mRNA to 18S signals after vs. before hyperperfusion, 0.94 +/- 0.08) or bFGF (1.08 +/- 0.05) but slightly increased that of TGF-beta1 (1.14 +/- 0.07; P < 0.03). In contrast, as previously found in the rat, electrical stimulation provoked more than a threefold increase in VEGF mRNA abundance (3.40 +/- 1.45; P < 0.02). However, electrical stimulation produced no significant changes in either bFGF (1.16 +/- 0.13) or TGF-beta1 (1.31 +/- 0.27). These results suggest that the increased muscle blood flow of exercise does not account for the increased abundance of these angiogenic growth factor mRNA levels in response to acute exercise. We speculate that other factors, such as local hypoxia, metabolite concentration changes, or mechanical effects of contraction per se, may be responsible for the effects of exercise.
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91
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Gavin TP, Derchak PA, Stager JM. Ventilation's role in the decline in VO2max and SaO2 in acute hypoxic exercise. Med Sci Sports Exerc 1998; 30:195-9. [PMID: 9502345 DOI: 10.1097/00005768-199802000-00004] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The role of ventilation in the response in aerobic capacity and arterial oxygen saturation (SaO2) to acute hypoxic exercise was studied in 13 healthy active men divided into two groups based on their normoxic maximal exercise VE/VO2 (LOW < or =27.7; HIGH > or = 30.2) and PAO2 estimates (LOW < or = 107 mm Hg; HIGH > or = 110 mm Hg). Groups performed two incremental progressive maximal cycle exercise (VO2max) tests: normoxia (FIO2 = 20.9%) and acute hypoxia (FIO2 = 13.3%). To evaluate the influence of hypoxic ventilatory drive on ventilation, resting hypoxic ventilatory response (rHVR) was measured. LOW demonstrated lower ventilatory responses (VE, VE/VO2, and VE/VCO2) during both normoxic and hypoxic exercise (P < or = 0.05). During maximal hypoxic exercise, LOW had a greater decline in both VO2max (21.6 mL x kg(-1) x min(-1) vs 16.6 mL x kg(-1) x min[-1]) and SaO2 (31.9% vs 22.1%). Modest but significant correlations were identified between normoxic VE/VO2 and the decline in both VO2max (r = -0.62) and SaO2 (r = -0.60). No correlations were identified between rHVR and any ventilatory response or SaO2. In summary, the results from this study suggest that a low exercise-induced hyperventilatory response is a significant mechanism in the arterial desaturation observed during hypoxic exercise and the decline in aerobic capacity associated with this desaturation. However, the ventilatory response to hypoxic exercise is not dependent upon hypoxic ventilatory drive.
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