Effects of Kefir on the Cardiac Autonomic Tones and Baroreflex Sensitivity in Spontaneously Hypertensive Rats.

Brunella F Klippel,Thiago M C Pereira,Bianca P Campagnaro,Tadeu U Andrade,Elisardo C Vasquez,Licia B Duemke,Rodolfo F Dalvi,Marcos A Leal,Andreia G F Friques,Silvana S Meyrelles,Agata L Gava,Eduardo M Dantas

doi:10.3389/fphys.2016.00211

Abstract

Aims: It has been previously shown that the probiotic kefir (a symbiotic matrix containing acid bacteria and yeasts) attenuated the hypertension and the endothelial dysfunction in spontaneously hypertensive rats (SHR). In the present study, the effect of chronic administration of kefir on the cardiac autonomic control of heart rate (HR) and baroreflex sensitivity (BRS) in SHR was evaluated.Methods: SHR were treated with kefir (0.3 mL/100 g body weight) for 60 days and compared with non-treated SHR and with normotensive Wistar-Kyoto rats. Cardiac autonomic vagal (VT) and sympathetic (ST) tones were estimated through the blockade of the cardiac muscarinic receptors (methylatropine) and the blockade of β1−adrenoceptor (atenolol). The BRS was evaluated by the tachycardia and bradycardia responses to vasoactive drug-induced decreases and increases in arterial blood pressure (BP), respectively. Additionally, spontaneous BRS was estimated by autoregressive spectral analysis.Results: Kefir-treated SHR exhibited significant attenuation of basal BP, HR, and cardiac hypertrophy compared to non-treated SHR (12, 13, and 21%, respectively). Cardiac VT and ST were significantly altered in the SHR (~40 and ~90 bpm) compared with Wistar rats (~120 and ~30 bpm) and were partially recovered in SHR-kefir (~90 and ~25 bpm). SHR exhibited an impaired bradycardic BRS (~50%) compared with Wistar rats, which was reduced to ~40% in the kefir-treated SHR and abolished by methylatropine in all groups. SHR also exhibited a significant impairment of the tachycardic BRS (~23%) compared with Wistar rats and this difference was reduced to 8% in the SHR-kefir. Under the action of atenolol the residual reflex tachycardia was smaller in SHR than in Wistar rats and kefir attenuated this abnormality. Spectral analysis revealed increased low frequency components of BP (~3.5-fold) and pulse interval (~2-fold) compared with Wistar rats and these differences were reduced by kefir-treatment to ~1.6- and ~1.5-fold, respectively. Spectral analysis also showed an impairment of spontaneous BRS in SHR, but kefir-treatment caused only a tendency to reverse this result.Conclusions: The novelty of this study is that daily chronic consumption of a low dose of kefir reduced the impairment of the cardiac autonomic control of HR and of the impaired BRS in SHR.

Highlights

In recent years, the fermented milks containing lactic acid bacteria, the so-called probiotics, including kefir, emerged as an alternative therapy due to the growing interest for wellbeing and healthy lifestyle
The global counting of microorganisms in the samples of milk fermented with kefir grains was 7.6 x 107 units forming colonies (UFC)/mL
The present study investigated the effects of multi-strain kefir on cardiovascular autonomic control and baroreflex sensitivity in spontaneously hypertensive rat (SHR) rats, since most of the available studies have focused on isolated bacteria providing limited information on the functional role of the widely consumed beverage obtained by fermentation of milk with kefir grains

Summary

Introduction

The fermented milks containing lactic acid bacteria, the so-called probiotics, including kefir, emerged as an alternative therapy due to the growing interest for wellbeing and healthy lifestyle. The spontaneously hypertensive rat (SHR) have been used as an important tool to understanding cardiovascular dysfunctions, such as high blood pressure (BP), endothelial injury and abnormal neural control of the cardiovascular system (Vasquez et al, 1997; Abreu et al, 1998; Blanco et al, 2015; Friques et al, 2015) In recent years, this hypertensive animal emerged as a promising model to identify alternative or non-pharmacological agents for prevention/treatment of cardiovascular disease because it develops essential hypertension (Ceroni et al, 2009; Monteiro et al, 2012; Barbosa Neto et al, 2013; Friques et al, 2015). The mechanisms of those actions included a partial correction of the reactive oxygen species/nitric oxide imbalance and the partial restoring of the endothelial architecture due to endothelial progenitor cells attraction

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Conclusion