The goal of this application is to test the hypothesis that human aging alters the regulation of blood flow to active skeletal Skeletal muscles during whole body exercise. Compelling evidence supporting this hypothesis comes from our recent finding that leg blood flow during submaximal cycle ergometry is reduced in older versus younger aerobically-trained men, despite similar cardiac output and leg muscle mass. To determine if reduced skeletal muscle perfusion duration exertion is an inevitable consequence of aging, and to clarify the mechanisms involved, we will address the following specific aims: 1) Is active muscle blood flow during exercise influenced by age, gender, or chronic physical activity? 2) Does an acute reduction in the work of breathing (inspired HeO2) during submaximal exercise augment active muscle blood flow to a greater extent in older compared to younger subjects and if so, how? 3) Is there evidence for an age-associated increase in sympathetic vasoconstriction in active skeletal muscle during exercise and if so, is this related to differences in muscle fiber type (needle biopsy)? 4) Does an aerobic exercise training program modify the effects of age on exercise hyperemia and vasodilator responsiveness in the leg? These questions will be investigated by measuring leg blood flow (femoral vein thermodilution), leg norepinephrine spillover, arterial pressure, and cardiac output (acetylene uptake) during graded leg cycle ergometry in healthy younger z920-30 years) and older (60-75 years) men and women. Leg muscle mass (DEXA) and leg vasodilator responses to local administration of prazosin (Aim 3) and endothelial-dependent and independent agonists (ACh, NTP, papavarine, Aim 4) will also be assessed as a function of age. We hypothesize that normal aging is associated with reduced active muscle vasodilation during dynamic exercise and that this is due to increased respiratory muscle blood flow demands, augmented sympathetic vasoconstriction in the legs, and impaired respiratory muscle blood flow demands, augmented sympathetic vasoconstriction in the legs, and impaired endothelium-dependent vasodilation. These investigations should contribute significantly to our understanding of the decline in physical functional capacity and increased incidence of chronic disease in older humans.
| Gonzales, J U; Tucker, S H; Kalasky, M J et al. (2012) Leg strength is associated with ventilatory efficiency in older women. Int J Sports Med 33:537-42 |
| Parker, Beth A; Kalasky, Martha J; Proctor, David N (2010) Evidence for sex differences in cardiovascular aging and adaptive responses to physical activity. Eur J Appl Physiol 110:235-46 |
| Gonzales, Joaquin U; Miedlar, Julie A; Parker, Beth A et al. (2010) Relation of femoral diameter, shear rate, and dilatory response to knee extensor exercise. Med Sci Sports Exerc 42:1870-5 |
| Ridout, Samuel J; Parker, Beth A; Smithmyer, Sandra L et al. (2010) Age and sex influence the balance between maximal cardiac output and peripheral vascular reserve. J Appl Physiol (1985) 108:483-9 |
| Parker, Beth A; Smithmyer, Sandra L; Ridout, Samuel J et al. (2008) Age and microvascular responses to knee extensor exercise in women. Eur J Appl Physiol 103:343-51 |
| Parker, Beth A; Smithmyer, Sandra L; Proctor, David N (2008) Hormone therapy is associated with preserved smooth muscle structure and dilation in the arterial vasculature of the leg in older women. Maturitas 59:46-54 |
| Parker, Beth A; Smithmyer, Sandra L; Pelberg, Justin A et al. (2008) Sex-specific influence of aging on exercising leg blood flow. J Appl Physiol 104:655-64 |
| Parker, Beth A; Smithmyer, Sandra L; Pelberg, Justin A et al. (2007) Sex differences in leg vasodilation during graded knee extensor exercise in young adults. J Appl Physiol 103:1583-91 |
| Parker, Beth A; Smithmyer, Sandra L; Jarvis, Sara S et al. (2007) Evidence for reduced sympatholysis in leg resistance vasculature of healthy older women. Am J Physiol Heart Circ Physiol 292:H1148-56 |
| Proctor, David N; Parker, Beth A (2006) Vasodilation and vascular control in contracting muscle of the aging human. Microcirculation 13:315-27 |
Showing the most recent 10 out of 21 publications
