Joshua R Smith1, K Sue Hageman2, Craig A Harms3, David C Poole4, Timothy I Musch4. 1. Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, United States; Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, 55901, United States. Electronic address: smith.joshua1@mayo.edu. 2. Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, United States. 3. Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, United States. 4. Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, United States; Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, United States.
Abstract
BACKGROUND: Respiratory muscle blood flows (BF) increase substantially during exercise in younger adult rats. As aging is associated with altered pulmonary function, we hypothesized that old rats will have greater intercostal muscle BF and vascular conductances (VC) than young rats during submaximal exercise. METHODS: Mean arterial pressure and respiratory muscle BFs (via carotid artery catheter and radiolabeled microspheres, respectively) were measured at rest and during submaximal exercise in young (n = 9) and old (n = 7) Fischer 344 X Brown Norway rats. RESULTS: At rest, diaphragm, intercostal, and transversus abdominis BFs and VCs were not different between groups (all, p > 0.10). During submaximal exercise, old compared to young rats had greater intercostal BF (40 ± 6 vs 25 ± 2 mL/min/100 g) and VC (0.30 ± 0.05 vs 0.18 ± 0.02 mL/min/mmHg/100 g) (both, p ≤ 0.01). Diaphragm and transversus abdominis BFs and VCs were not different between groups during exercise (all, p > 0.24). CONCLUSIONS: These data demonstrate that intercostal muscle BF and VC are increased in old compared to young rats during submaximal exercise.
BACKGROUND: Respiratory muscle blood flows (BF) increase substantially during exercise in younger adult rats. As aging is associated with altered pulmonary function, we hypothesized that old rats will have greater intercostal muscle BF and vascular conductances (VC) than young rats during submaximal exercise. METHODS: Mean arterial pressure and respiratory muscle BFs (via carotid artery catheter and radiolabeled microspheres, respectively) were measured at rest and during submaximal exercise in young (n = 9) and old (n = 7) Fischer 344 X Brown Norway rats. RESULTS: At rest, diaphragm, intercostal, and transversus abdominis BFs and VCs were not different between groups (all, p > 0.10). During submaximal exercise, old compared to young rats had greater intercostal BF (40 ± 6 vs 25 ± 2 mL/min/100 g) and VC (0.30 ± 0.05 vs 0.18 ± 0.02 mL/min/mmHg/100 g) (both, p ≤ 0.01). Diaphragm and transversus abdominis BFs and VCs were not different between groups during exercise (all, p > 0.24). CONCLUSIONS: These data demonstrate that intercostal muscle BF and VC are increased in old compared to young rats during submaximal exercise.
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