Open AccessSympathetic activation due to limb venous distension is preserved during muscle metaboreceptor stimulation
Author(s) -
Jian Cui,
Cheryl Blaha,
Urs A. Leuenberger,
Lawrence I. Sinoway
Publication year - 2021
Publication title -
american journal of physiology. regulatory, integrative and comparative physiology/american journal of physiology. regulatory, integrative, and comparative physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.266
H-Index - 175
eISSN - 1522-1490
pISSN - 0363-6119
DOI - 10.1152/ajpregu.00305.2020
Subject(s) - medicine , distension , reflex , blood pressure , anesthesia , heart rate , saline , microneurography , forearm , hemodynamics , sympathetic nervous system , baroreflex , anatomy
Venous saline infusions in an arterially occluded forearm evoke reflex increases in muscle sympathetic nerve activity (MSNA) and blood pressure (BP) in humans (venous distension reflex). It is unclear if the inputs from metabolically sensitive skeletal muscle afferents (i.e., muscle metaboreflex) would modify the venous distension reflex. We hypothesized that muscle metaboreceptor stimulation might augment the venous distension reflex. BP (Finapres), heart rate (ECG), and MSNA (microneurography) were assessed in 18 young healthy subjects. In trial A , saline (5% forearm volume) was infused into the veins of an arterially occluded arm (nonhandgrip trial). In trial B , subjects performed 2-min static handgrip followed by postexercise circulatory occlusion (PECO) of the arm. During PECO, saline was infused into the veins of the arm (handgrip trial). In trial A , the infusion increased MSNA and BP as expected (both P < 0.001). In trial B , handgrip significantly raised MSNA, BP, and venous lactic acid concentrations. Venous saline infusion during PECO further raised MSNA and BP (both P < 0.001). The changes in MSNA (Δ8.6 ± 1.5 to Δ10.6 ± 1.8 bursts/min, P = 0.258) and mean arterial pressure ( P = 0.844) evoked by the infusion during PECO were not significantly different from those in the nonhandgrip trial. These observations indicate that venous distension reflex responses are preserved during sympathetic activation mediated by the muscle metaboreflex.