Open AccessThe exercise pressor reflex and active O 2 transport in peripheral arterial disease
Author(s) -
Stavres Jon,
Sica Christopher T.,
Blaha Cheryl,
Herr Michael,
Wang Jianli,
Pai Samuel,
Cauffman Aimee,
Vesek Jeffrey,
Yang Qing X.,
Sinoway Lawrence I.
Publication year - 2019
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.14243
Subject(s) - medicine , perfusion , peripheral , reflex , anesthesia , arterial disease , blood pressure , oxygenation , mean arterial pressure , oxygen saturation , cardiology , heart rate , vascular disease , oxygen , chemistry , organic chemistry
It is unclear if the exaggerated exercise pressor reflex observed in peripheral arterial disease (PAD) patients facilitates Oxygen (O 2 ) transport during presymptomatic exercise. Accordingly, this study compared O 2 transport between PAD patients and healthy controls during graded presymptomatic work. Seven PAD patients and seven healthy controls performed dynamic plantar flexion in the bore of a 3T MRI scanner. Perfusion, T 2 * (an index of relative tissue oxygenation), and SvO 2 (a measure of venous oxygen saturation) were collected from the medial gastrocnemius (MG) during the final 10 seconds of each stage. Blood pressure was also collected during the final minute of each stage. As expected, the pressor response to presymptomatic work (4 kg) was exaggerated in PAD patients compared to controls (+14 mmHg ± 4 and +7 mmHg ± 2, P ≤ 0.034). When normalized to changes in free water content (S 0 ), T 2 * was lower at 2 kg in PAD patients compared to controls (−0.91 Δms/ΔAU ± 0.3 and 0.57 Δms/ΔAU ± 0.3, P ≤ 0.008); followed by a greater increase in perfusion at 4 kg in the PAD group (+18.8 mL/min/100g ± 6.2 vs. −0.21 mL/min/100g ± 3.2 in PAD and controls, P ≤ 0.026). Lastly, SvO 2 decreased at 4 kg in both groups (−13% ± 4 and −2% ± 4 in PAD and controls, P ≤ 0.049), suggesting an increase in O 2 extraction in the PAD group. Based on these findings, O 2 transport appears to be augmented during graded presymptomatic work in PAD patients, and this may be partially mediated by an exaggerated pressor response.