Effect of age and handgrip exercise on renal oxygenation in healthy adults
| Author(s) | Chouramanis, Nicholas | |
| Date Accessioned | 2023-02-09T15:19:59Z | |
| Date Available | 2023-02-09T15:19:59Z | |
| Publication Date | 2022 | |
| SWORD Update | 2022-09-21T16:08:12Z | |
| Abstract | Normal aging is associated with significant increases in blood pressure and arterial stiffness, which partially contribute to kidney function decline. Additionally, renal hypoxia has been implicated as a common pathway in the development and progression of renal diseases. However, this is mostly supported by animal studies and computational models. Advancement of modern magnetic resonance imaging (MRI) techniques now permits the assessment of renal oxygenation in humans so that we may better understand the effect of aging on renal oxygenation. Currently, there is limited research that demonstrates mixed results regarding changes in renal oxygenation in healthy aging humans. OBJECTIVES: 1) Determine resting renal oxygenation in older and younger adults as well as evaluate the association between arterial stiffness and renal oxygenation in older adults. 2) Evaluate the effect of age and handgrip (HG) exercise on renal oxygenation in older and younger adults. HYPOTHESES: 1) Cortical and medullary oxygenation will be significantly reduced in older adults compared to younger adults. Arterial stiffness will be negatively associated with cortical oxygenation in older adults. 2) Changes in renal oxygenation during HG exercise will be exaggerated in older adults compared to younger adults. METHODS: Healthy, non-hypertensive and non-obese older and younger adults were recruited. After consent and screening, subjects underwent testing over the course of 2 visits. Carotid-femoral pulse wave velocity (cf-PWV), a measure of arterial stiffness, was assessed via applanation tonometry. Blood-oxygen level dependent (BOLD)-MRI was used to assess the relaxation rate (R2*), a surrogate measure of tissue oxygenation, of the cortex and medulla in the kidney at rest and in response to a 3-minute bout of HG exercise at 30% maximal voluntary contraction. Elevated R2* suggests decreased oxygenation. RESULTS: 13 old healthy (8F/5M; Age: 67±6 years; BMI: 23.8±2.8 kg/m2; MAP: 86±7 mmHg) and 14 young healthy (7F/7M; Age: 27±3 years; BMI: 23.3±2.2 kg/m2; MAP: 77±9 mmHg) adults were recruited. Resting cortical R2* (22.2±3.1 vs. 19.4±1.9 s-1; p=0.009) and medullary R2* (27.3±3.5 vs 22.5±2.7 s-1; p<0.001) were significantly increased in older adults versus younger adults. Cf-PWV was elevated in older adults (8.4±1.9 vs. 5.6±0.7 m/s; p<0.001) but was not associated with cortical oxygenation (r=0.232; p=0.446). In response to HG exercise, changes were observed in cortical R2* (∆4.9±7.6 vs. 9.3±8.2 %) and medullary R2* (∆1.7±5.7 vs 5.1±8.5 %), but there was no difference in the response between older and younger healthy adults. (p=0.162 cortex; p=0.237 medulla). CONCLUSION: Renal oxygenation is significantly reduced in older adults at rest and is not associated with arterial stiffness. Changes in renal oxygenation in response to HG exercise are significant, but not different between older and younger adults. | |
| Advisor | Edwards, David A. | |
| Degree | Ph.D. | |
| Department | University of Delaware, Department of Kinesiology and Applied Physiology | |
| DOI | https://doi.org/10.58088/wys8-d084 | |
| Unique Identifier | 1369265414 | |
| URL | https://udspace.udel.edu/handle/19716/32254 | |
| Language | en | |
| Publisher | University of Delaware | |
| URI | https://login.udel.idm.oclc.org/login?url=https://www.proquest.com/dissertations-theses/effect-age-handgrip-exercise-on-renal-oxygenation/docview/2723382419/se-2?accountid=10457 | |
| Keywords | Healthy aging | |
| Keywords | Arterial stiffness | |
| Keywords | Relaxation rate | |
| Keywords | Renal oxygenation | |
| Title | Effect of age and handgrip exercise on renal oxygenation in healthy adults | |
| Type | Thesis |