Low-level Chronic Lead Exposure Impairs Neural Control of Blood Pressure and Heart Rate in Rats.
Lead (Pb) induces adverse effects when it chronically accumulates in the body, including effects on the nervous and cardiovascular systems. Wistar rats were exposed to lead acetate for 30 days (first dose 4 µg/100 g followed by 0.05 µg/100 g/day, i.m.) to investigate the cardiovascular system impact on the autonomic control. The femoral artery and vein were catheterised to perform hemodynamic evaluations in awake rats: heart rate variability (HRV), baroreflex sensitivity, cardiopulmonary reflex and hemodynamic responses to vagal and sympathetic pharmacological blockade. Rats exposed to Pb exhibited a higher blood pressure and reduced HRV in the time domain when compared to the saline-injected group. Spectral analysis of the HRV in the frequency-domain showed an augmented low-frequency component of the spectrum. Methylatropine and atenolol administration suggest increased sympathetic tone and reduced vagal tone on the control of heart rate. Chronic Pb exposure decreased the sensitivity of the baroreflex without significantly changing the cardiopulmonary reflex. This study demonstrated for the first time in an animal model of a controlled, low-dose chronic lead exposure that cardiovascular changes, such as arterial hypertension, are accompanied by impaired autonomic control of the cardiovascular system, as characterised by reduced baroreflex sensitivity and a sympathovagal imbalance.
Department of Physiological Sciences, Federal University of Espirito Santo, Avenida Marechal Campos, 1468, Maruípe, Vitoria, ES, 29043-900, Brazil. yllars@hotmail.com.|Programa de Pós-Graduação em Ciências Fisiológicas, CCS/UFES, Av. Marechal Campos, 1468. Maruípe, Vitoria, ES, 29040-091, Brazil. yllars@hotmail.com.
Maylla Ronacher
MR
Simões
Department of Physiological Sciences, Federal University of Espirito Santo, Avenida Marechal Campos, 1468, Maruípe, Vitoria, ES, 29043-900, Brazil.
Silvio César
SC
Preti
Department of Physiological Sciences, Federal University of Espirito Santo, Avenida Marechal Campos, 1468, Maruípe, Vitoria, ES, 29043-900, Brazil.
Bruna Fernandes
BF
Azevedo
Department of Physiological Sciences, Federal University of Espirito Santo, Avenida Marechal Campos, 1468, Maruípe, Vitoria, ES, 29043-900, Brazil.
Jonaína
J
Fiorim
Department of Physiological Sciences, Federal University of Espirito Santo, Avenida Marechal Campos, 1468, Maruípe, Vitoria, ES, 29043-900, Brazil.|Health Sciences Center, EMESCAM, Avenida Nossa Senhora da Penha, 2190, Santa Luiza, Vitoria, ES, 29045-402, Brazil.
David D
DD
Freire
Department of Physiological Sciences, Federal University of Espirito Santo, Avenida Marechal Campos, 1468, Maruípe, Vitoria, ES, 29043-900, Brazil.
Emilia Polaco
EP
Covre
Department of Physiological Sciences, Federal University of Espirito Santo, Avenida Marechal Campos, 1468, Maruípe, Vitoria, ES, 29043-900, Brazil.|Health Sciences Center, EMESCAM, Avenida Nossa Senhora da Penha, 2190, Santa Luiza, Vitoria, ES, 29045-402, Brazil.|Programa de Pós-Graduação em Ciências Fisiológicas, CCS/UFES, Av. Marechal Campos, 1468. Maruípe, Vitoria, ES, 29040-091, Brazil.
Dalton Valentim
DV
Vassallo
Department of Physiological Sciences, Federal University of Espirito Santo, Avenida Marechal Campos, 1468, Maruípe, Vitoria, ES, 29043-900, Brazil.|Programa de Pós-Graduação em Ciências Fisiológicas, CCS/UFES, Av. Marechal Campos, 1468. Maruípe, Vitoria, ES, 29040-091, Brazil.
Leonardo
L
Dos Santos
D000818:Animals; D017704:Baroreflex; D001794:Blood Pressure; D002319:Cardiovascular System / Q000294:innervation*; D004195:Disease Models, Animal; D006339:Heart Rate; D020263:Lead Poisoning, Nervous System / Q000209:etiology / Q000503:physiopathology*; D009942:Organometallic Compounds; D017208:Rats, Wistar; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D013997:Time Factors; D014630:Vagus Nerve / Q000503:physiopathology*
D009942:Organometallic Compounds; C008261:lead acetate
Baroreflex; Chemoreflex; Heavy metal; Intoxication; Sympathetic tone; Trace element