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Traylor MK, Batman GB, Sears KN, Ransom KV, Hammer SM, Keller JL. Sex-specific microvascular and hemodynamic responses to passive limb heating in young adults. Microcirculation 2024; 31:e12848. [PMID: 38281244 DOI: 10.1111/micc.12848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 12/20/2023] [Accepted: 01/17/2024] [Indexed: 01/30/2024]
Abstract
OBJECTIVE We examined sex-specific microvascular reactivity and hemodynamic responses under conditions of augmented resting blood flow induced by passive heating compared to normal blood flow. METHODS Thirty-eight adults (19 females) completed a vascular occlusion test (VOT) on two occasions preceded by rest with or without passive heating in a randomized, counterbalanced order. Skeletal muscle tissue oxygenation (StO2, %) was assessed with near-infrared spectroscopy (NIRS), and the rate of desaturation and resaturation as well as maximal StO2 (StO2max) and prolonged hypersaturation (area under the curve, StO2AUC) were quantified. Before the VOT, brachial artery blood flow (BABF), vascular conductance, and relative BABF (BABF normalized to forearm lean mass) were determined. Sex × condition ANOVAs were used. A p-value ≤.05 was considered statistically significant. RESULTS Twenty minutes of heating increased BABF compared to the control (102.9 ± 28.3 vs. 36.0 ± 20.9 mL min-1; p < .01). Males demonstrated greater BABF than females (91.9 ± 34.0 vs. 47.0 ± 19.1 mL min-1; p < .01). There was no sex difference in normalized BABF. There were no significant interactions for NIRS-VOT outcomes, but heat did increase the rate of desaturation (-0.140 ± 0.02 vs. -0.119 ± 0.03% s-1; p < .01), whereas regardless of condition, males exhibited greater rates of resaturation and StO2max than females. CONCLUSIONS These results suggest that blood flow is not the primary factor causing sex differences in NIRS-VOT outcomes.
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Affiliation(s)
- Miranda K Traylor
- Integrative Laboratory of Exercise and Applied Physiology (iLEAP), Department of Health, Kinesiology, and Sport, College of Education and Professional Studies, University of South Alabama, Mobile, Alabama, USA
| | - Genevieve B Batman
- Integrative Laboratory of Exercise and Applied Physiology (iLEAP), Department of Health, Kinesiology, and Sport, College of Education and Professional Studies, University of South Alabama, Mobile, Alabama, USA
| | - Kylie N Sears
- School of Kinesiology, Applied Health and Recreation, Oklahoma State University, Stillwater, Oklahoma, USA
| | - Kyndall V Ransom
- Integrative Laboratory of Exercise and Applied Physiology (iLEAP), Department of Health, Kinesiology, and Sport, College of Education and Professional Studies, University of South Alabama, Mobile, Alabama, USA
- Chemistry Department, College of Arts and Science, University of South Alabama, Mobile, Alabama, USA
| | - Shane M Hammer
- School of Kinesiology, Applied Health and Recreation, Oklahoma State University, Stillwater, Oklahoma, USA
| | - Joshua L Keller
- Integrative Laboratory of Exercise and Applied Physiology (iLEAP), Department of Health, Kinesiology, and Sport, College of Education and Professional Studies, University of South Alabama, Mobile, Alabama, USA
- Department of Physiology & Cell Biology, College of Medicine, University of South Alabama, Mobile, Alabama, USA
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