Medullary Noradrenergic Neurons Mediate Hemodynamic Responses to Osmotic and Volume Challenges

Frontiers in Physiology

Talita de Melo e Silva¹  Eduardo Colombari²  Rodrigo Mello Gomes³  Carlos Henrique de Castro³  James Oluwagbamigbe Fajemiroye³  Carlos Henrique Xavier³  Gustavo Rodrigues Pedrino³  Lara Marques Naves³  Andre Henrique Freiria-Oliveira³  Stefanne Madalena Marques³  Keilah Valéria Naves Cavalcante³  Marcos Luiz Ferreira-Neto⁴  Juliana Milan Alves⁴ 

[1] Department of Physiology and Biophysics, Institute of Biomedical Science, University of São Paulo, São Paulo, Brazil;Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, Brazil;Department of Physiology, Biological Sciences Institute, Federal University of Goiás, Goiânia, Brazil;Department of Physiology, Institute of Biomedical Sciences, Federal University of Uberlândia, Uberlândia, Brazil;

关键词: central nervous system;    resuscitation;    lesion;    blood pressure;    hypertonic saline;   

DOI  :  10.3389/fphys.2021.649535

来源: DOAJ

【 摘 要 】

Despite being involved in homeostatic control and hydro-electrolyte balance, the contribution of medullary (A1 and A2) noradrenergic neurons to the hypertonic saline infusion (HSI)-induced cardiovascular response after hypotensive hemorrhage (HH) remains to be clarified. Hence, the present study sought to determine the role of noradrenergic neurons in HSI-induced hemodynamic recovery in male Wistar rats (290–320 g) with HH. Medullary catecholaminergic neurons were lesioned by nanoinjection of antidopamine-β-hydroxylase–saporin (0.105 ng·nl−1) into A1, A2, or both (LES A1; LES A2; or LES A1+A2, respectively). Sham rats received nanoinjections of free saporin in the same regions (SHAM A1; SHAM A2; or SHAM A1+A2, respectively). After 15 days, rats were anesthetized and instrumented for cardiovascular recordings. Following 10 min of stabilization, HH was performed by withdrawing arterial blood until mean arterial pressure (MAP) reaches 60 mmHg. Subsequently, HSI was performed (NaCl 3 M; 1.8 ml·kg−1, i.v.). The HH procedure caused hypotension and bradycardia and reduced renal, aortic, and hind limb blood flows (RBF, ABF, and HBF). The HSI restored MAP, heart rate (HR), and RBF to baseline values in the SHAM, LES A1, and LES A2 groups. However, concomitant A1 and A2 lesions impaired this recovery, as demonstrated by the abolishment of MAP, RBF, and ABF responses. Although lesioning of only a group of neurons (A1 or A2) was unable to prevent HSI-induced recovery of cardiovascular parameters after hemorrhage, lesions of both A1 and A2 made this response unfeasible. These findings show that together the A1 and A2 neurons are essential to HSI-induced cardiovascular recovery in hypovolemia. By implication, simultaneous A1 and A2 dysfunctions could impair the efficacy of HSI-induced recovery during hemorrhage.

【 授权许可】

Unknown