Influence of ovariectomy in the right ventricular contractility in heart failure rats.
BACKGROUND
Clinical studies in postmenopausal women suggest that female hormones play an important role in maintaining healthy cardiovascular conditions. The objective of this study was to evaluate the influence of ovarian hormones in the right ventricle contractility in heart failure (HF) rats following myocardial infarction (MI).


METHODS
Female Wistar rats were divided into four groups: healthy ovariectomized (OVX), ovariectomized with HF (OVX-HF), HF, and sham operated (SHAM). Ovariectomy was performed in 10-week-old rats, and MI was induced 1 week later. Eight weeks after MI, right ventricular (RV) performance was analyzed using RV strip preparations.


RESULTS
Ovariectomy did not change the infarct size (HF: 42 +/- 3.5 vs. OVX-HF: 39 +/- 1.5%). In the presence of isoproterenol (ISO) and calcium, the isometric force was reduced in both HF groups. Ovariectomy did not modify the positive inotropic parameter in the control and in HF rats. Time to peak tension (TPT) was prolonged in both ovariectomized groups compared to SHAM (ISO 10(-7) M OVX: 125 +/- 12( *); SHAM: 81 +/- 4; HF: 87 +/- 4; OVX-HF: 102 +/- 6( *) msec, ( *)p <0.01 vs. SHAM), and relaxation time (RT) was prolonged in OVX (270 +/- 16( *) msec) and OVX-HF (241 +/- 10( *) msec) vs. SHAM (197 +/- 6 msec; ( *)p <0.01 vs. SHAM).


CONCLUSIONS
We conclude that the absence of female ovarian hormones during nine weeks does not influence the right ventricle positive inotropic response, but it prolongs the time of contraction and relaxation in normal and in HF rats following MI.
Giuberti
Karina
K
Department of Physiological Sciences, Federal University of Espirito Santo, Vitória, ES, Brazil.
Pereira
Raquel Binda
RB
Bianchi
Patricia Rocon
PR
Paigel
Altemar Santos
AS
Vassallo
Dalton Valentim
DV
Stefanon
Ivanita
I
D000818:Animals; D002303:Cardiac Output, Low / Q000209:etiology / Q000503:physiopathology*; D002316:Cardiotonic Agents / Q000494:pharmacology; D004967:Estrogens / Q000502:physiology*; D005260:Female; D006352:Heart Ventricles / Q000187:drug effects; D007545:Isoproterenol / Q000494:pharmacology; D009200:Myocardial Contraction / Q000187:drug effects; D009203:Myocardial Infarction / Q000150:complications*; D010052:Ovariectomy; D051381:Rats; D017208:Rats, Wistar; D018497:Ventricular Dysfunction, Right / Q000503:physiopathology*
D002316:Cardiotonic Agents; D004967:Estrogens; D007545:Isoproterenol