Slow force response modulation by ω3 fatty acid supplementation in ovariectomized rats

GARCIA R; ZAVALA MR; DIAZ RG; PINILLA, OA; VELEZ RUEDA OJ; MARTÍNEZ V; LOFEUDO, JUAN MANUEL; PEREZ, NG; DE GIUSTI VC,; VILLA ABRILLE MC

Congreso; ISHR-Lat Annual meeting; 2022

ISHR-Lat

The stretch of cardiac muscle increases developed force in two phases: an initial rapid one, followed by a slowly developing one called ?slow force response? (SFR). Acute activation of cardiac Na+/H+ exchanger (NHE1) plays a crucial role in the development of the adaptative SFR. However, sustained (chronic) exchanger hyperactivity may lead to cardiovascular disease. It is well known that women after menopause increase cardiovascular risk. Interestingly, recent own experiments in cardiomyocytes from ovariectomized rats (process that mimics menopause) demonstrated NHE1 overexpression and hyperactivity. On the other hand, several studies have shown that consumption of omega-3 polyunsaturated fatty acids (ω3-FA) has cardioprotective effects. In this context, the present study was aimed to characterize the SFR in OVX rats, and to evaluate the possible effects of a ω3-FA supplemented diet on this important mechanism. Two-month-old female rats were subjected to a bilateral ovariectomy (OVX group). A Sham (S) operated group (ovaries exposed but not dissected) was used as control. Thirty days after surgery, animals were aleatory separated to either follow receiving standard rat chow (untreated S and OVX) or begin an oral supplementation of ω3-FA (Sω3 and OVXω3, 200 mg/kg/day, weekly adjusted for body weight) during the next 3 months. Systolic blood pressure (SBP) and body weight were determined (before surgery, during treatment and at sacrifice). The SFR development was measured in isolated left ventricle papillary muscles. Successful ovariectomy was confirmed by uterine atrophy, procedure that also promoted an increase in body weight without affecting SBP. Diet supplementation did not modify these parameters. Left ventricular mass index LVMI (mg/mm, used as hypertrophic parameter) showed a slight not significant tendence to be higher in OVX and OVXω3 rats. A similar SFR was observed in S, Sw3 and OVX rats (112,9 ± 6,1%, n=3; 114,5 ± 1,9 %, n=2; 119,7 ± 1,7 %, n=4, respectively, ns). In contrast, a significant decrease in SFR was observed in OVXω3 animals (103,3 ± 1,2 %, n= 4, p