ORIGINAL RESEARCH article
Front. Pain Res.
Sec. Pain Mechanisms
Volume 6 - 2025 | doi: 10.3389/fpain.2025.1593939
Anti-nociceptive properties of cardiopulmonary baroreceptors in patients with chronic back pain
Provisionally accepted
- 1University of Kansas Medical Center, Kansas City, United States
- 2Kansas City University, Kansas City, Missouri, United States
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Reduced pain perception following a persistent noxious stimulus during a study session (shortterm habituation) is believed to be partially mediated by descending inhibitory mechanisms, although these mechanisms have not been fully elucidated. We examined the hypothesis that cardiopulmonary baroreceptor unloading via lower body negative pressure (LBNP), which reduces central venous pressure, would significantly increase short-term habituation in chronic back pain (CBP) patients. A short-term habituation protocol was utilized that involved 1-sec pulses (×10) at 105% heat pain threshold on the anterior forearm at 0.5 Hz. Short-term habituation was observed in young, healthy participants (n=11), as indicated by a reduction in subjective pain ratings across the 10 repetitive heat pulses (-42% ± 29, P<0.01, n=11). Short-term habituation was also observed in CBP patients (-32% ± 30, P<0.01, n=12). Cardiopulmonary baroreceptor unloading via LBNP significantly reduced pain ratings across the 10 repetitive heat pulses in CBP patients compared with supine control (patient positioned in LBNP chamber but without a reduction in pressure) and upright sitting (chair), as indicated by a more negative area under the curve index (LBNP:-16.3±4.1; Control:-14.4±2.6; Upright sitting:-15.1±4.1, P=0.02). However, LBNP-mediated reductions in pain ratings were selective to CBP patients with more severe symptoms, i.e., neuropathic pain (LBNP:-14.7±2.1; Control:-12.8±1.4; Upright sitting:-12.1±1.2, P=0.04), whereas no effect of LBNP was observed in young, healthy participants (P=0.83). In support, CBP patients with neuropathic pain exhibited significantly elevated mechanical pressure pain threshold during LBNP (P=0.04). Together, these findings demonstrate an association between cardiopulmonary baroreceptor unloading and a reduction in pain perception during repetitive noxious stimuli in CBP patients, particularly among CBP patients with greater pain severity.
Keywords: Baroreflex, Chronic Pain, cardiopulmonary, Descending inhibition, sympathetic nerve activity, Sympathetic nerve activity (SNA)
Received: 19 Mar 2025; Accepted: 02 Jul 2025.
Copyright: © 2025 Iwakuma, Liu, Clonch, Gangwish, Holwerda and Lam. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Seth Holwerda, University of Kansas Medical Center, Kansas City, United States
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