TY - JOUR
T1 - The pressor response to concurrent stimulation of the mesencephalic locomotor region and peripheral sensory afferents is attenuated in normotensive but not hypertensive rats
AU - Liang, Nan
AU - Iwamoto, Gary A.
AU - Downey, Ryan M.
AU - Mitchell, Jere H.
AU - Smith, Scott A.
AU - Mizuno, Masaki
N1 - Funding Information:
This research was supported by grants from the National Institutes of Health Heart, Lung, and Blood Institute (HL-088422 to SS) and the Lawson & Rogers Lacy Research Fund in Cardiovascular Disease (to JM). NL was supported by a research fellowship (Institutional Program for Young Researcher Overseas Visits, Hiroshima University) and Grants-in-Aid (22700536) for Young Scientists (B) from the Japan Society for the Promotion of Science.
Publisher Copyright:
Copyright © 2019 Liang, Iwamoto, Downey, Mitchell, Smith and Mizuno. 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) and the copyright owner(s) 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.
PY - 2019
Y1 - 2019
N2 - Central command (CC) and the exercise pressor reflex (EPR) regulate blood pressure during exercise. We previously demonstrated that experimental stimulation of the CC and EPR pathways independently contribute to the exaggerated pressor response to exercise in hypertension. It is known that CC and EPR modify one another functionally. Whether their interactive relationship is altered in hypertension, contributing to the generation of this potentiated blood pressure response, remains unknown. To address this issue, the pressor response to activation of the CC pathway with and without concurrent stimulation of the EPR pathway, and vice versa, was examined in normotensive Wistar Kyoto (WKY) and spontaneously hypertensive (SHR) rats. In decerebrated, paralyzed animals, activation of the CC pathway was evoked by electrical stimulation of the mesencephalic locomotor region (MLR; 20–50 μA in 10-μA steps). Electrical stimulation of the sciatic nerve (SN, 3, 5, and 10 × motor threshold; MT) was used to activate hindlimb afferents known to carry EPR sensory information. In both WKY and SHR, the algebraic sum of the pressor responses to individual stimulation of the MLR and SN were greater than when both inputs were stimulated simultaneously. Although the blood pressure response to a constant level of SN stimulation was not significantly affected by concurrent MLR stimulation at variable intensities, the pressor response to a constant level of MLR simulation was significantly attenuated by concurrent SN stimulation in WKY but not in SHR. These findings suggest the interactive relationship between CC and the EPR is inhibitory in nature in both WKY and SHR. However, the neural occlusion between these central and peripheral pressor mechanisms is attenuated in hypertension.
AB - Central command (CC) and the exercise pressor reflex (EPR) regulate blood pressure during exercise. We previously demonstrated that experimental stimulation of the CC and EPR pathways independently contribute to the exaggerated pressor response to exercise in hypertension. It is known that CC and EPR modify one another functionally. Whether their interactive relationship is altered in hypertension, contributing to the generation of this potentiated blood pressure response, remains unknown. To address this issue, the pressor response to activation of the CC pathway with and without concurrent stimulation of the EPR pathway, and vice versa, was examined in normotensive Wistar Kyoto (WKY) and spontaneously hypertensive (SHR) rats. In decerebrated, paralyzed animals, activation of the CC pathway was evoked by electrical stimulation of the mesencephalic locomotor region (MLR; 20–50 μA in 10-μA steps). Electrical stimulation of the sciatic nerve (SN, 3, 5, and 10 × motor threshold; MT) was used to activate hindlimb afferents known to carry EPR sensory information. In both WKY and SHR, the algebraic sum of the pressor responses to individual stimulation of the MLR and SN were greater than when both inputs were stimulated simultaneously. Although the blood pressure response to a constant level of SN stimulation was not significantly affected by concurrent MLR stimulation at variable intensities, the pressor response to a constant level of MLR simulation was significantly attenuated by concurrent SN stimulation in WKY but not in SHR. These findings suggest the interactive relationship between CC and the EPR is inhibitory in nature in both WKY and SHR. However, the neural occlusion between these central and peripheral pressor mechanisms is attenuated in hypertension.
KW - Blood pressure
KW - Central command
KW - Exercise pressor reflex
KW - Hypertension
KW - Mesencephalic locomotor region
KW - Sympathetic nerve activity
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U2 - 10.3389/fphys.2019.00095
DO - 10.3389/fphys.2019.00095
M3 - Article
C2 - 30814955
AN - SCOPUS:85065995678
SN - 1664-042X
VL - 10
JO - Frontiers in Physiology
JF - Frontiers in Physiology
IS - FEB
M1 - 95
ER -