Mechanical work and energetic analysis of eccentric cardiac remodeling in a volume overload heart failure in rats.
Eccentric cardiac remodeling seen in dilated cardiomyopathy or regurgitant valvular disease is a well-known process of heart failure progression, but its mechanoenergetic profile has not been yet established. We made a volume overload (VO) heart failure model in rats and for the first time investigated left ventricular (LV) mechanical work and energetics in cross-circulated whole heart preparations. Laparotomy was performed in 14 Wistar male rats, and abdominal aortic-inferior vena caval shunt was created in seven rats (VO group). Another seven rats underwent a sham operation without functional shunt (Sham group). LV dimensions changes were followed with weekly transthoracic echocardiography. Three months after surgery, we measured LV pressure and volume and myocardial O(2) consumption in isolated heart cross circulation. LV internal dimensions in both systolic and diastolic phases were significantly increased in the VO group versus the Sham group (P < 0.05). LV pressure was markedly decreased in the VO group versus in the Sham group (P < 0.05). LV end-systolic pressure-volume relation shifted downward, and myocardial O(2) consumption related to Ca(2+) handling significantly decreased. The contractile response to Ca(2+) infusion was attenuated. Nevertheless, the increase in Ca(2+) handling-related O(2) consumption per unit change in LV contractility in the VO group was significantly higher than that in the Sham group (P < 0.05). The levels of sarco(endo)plasmic reticulum Ca(2+)-ATPase 2a protein were reduced in the VO group (P < 0.01). In conclusion, VO failing rat hearts had a character of marked contractile dysfunction accompanied with less efficient energy utilization in the Ca(2+) handling processes. These results suggest that restoring Ca(2+) handling in excitation-contraction coupling would improve the contractility of the myocardium after eccentric cardiac remodeling.
Takewa
Yoshiaki
Y
Cardiovascular Research Center, Mount Sinai School of Medicine, One Gustave Levy Place, Box 1030, New York, NY 10029, USA. roger.hajjar@mssm.edu
Chemaly
Elie R
ER
Takaki
Miyako
M
Liang
Li Fan
LF
Jin
Hongwei
H
Karakikes
Ioannis
I
Morel
Charlotte
C
Taenaka
Yoshiyuki
Y
Tatsumi
Eisuke
E
Hajjar
Roger J
RJ
D000818:Animals; D001166:Arteriovenous Shunt, Surgical; D001696:Biomechanical Phenomena; D002118:Calcium / Q000378:metabolism; D004195:Disease Models, Animal; D004452:Echocardiography; D004734:Energy Metabolism / Q000502:physiology*; D006333:Heart Failure / Q000503:physiopathology*; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000378:metabolism; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging / Q000503:physiopathology*; D020257:Ventricular Remodeling / Q000502:physiology*
D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D002118:Calcium