Table 2.
Two-dimensional and M-mode echocardiographic parameters of left ventricular structure and function in high-fat diet-fed obesity-prone and in normal chow-fed obesity-resistant rats during 4 and 12 months.
| 4 months | 12 months | p 4- vs. 12-month high fat diet in OP rats | |||||
|---|---|---|---|---|---|---|---|
| Normal chow in OR rats (n = 8) |
High fat diet in OP rats (n = 10) |
p |
Normal chow
in OR rats (n = 8) |
High fat diet in OP rats (n = 14) | p | ||
| Heart rate (in beats/min) |
258 ± 13 | 257 ± 10 | NS | 227 ± 5 | 208 ± 8 | NS | NS |
| Relative LV wall surface area | 0.53 ± 0.01 | 0.52 ± 0.02 | NS | 0.54 ± 0.01 | 0.59 ± 0.02 | * | †† |
| LVEF (in %) |
63 ± 2 | 68 ± 5 | NS | 63 ± 2 | 69 ± 3 | NS | NS |
| FS (in %) | 30 ± 1 | 34 ± 3 | NS | 30 ± 1 | 35 ± 3 | NS | NS |
| LVIDd (in mm) |
1.80 ± 0.04 | 1.77 ± 0.07 | NS | 1.78 ± 0.05 | 1.79 ± 0.08 | NS | NS |
| LVRWT | 0.42 ± 0.02 | 0.47 ± 0.03 | NS | 0.42 ± 0.02 | 0.51 ± 0.03 | * | NS |
| Stroke volume (in mL) |
0.26 ± 0.04 | 0.25 ± 0.02 | NS | 0.23 ± 0.01 | 0.28 ± 0.02 | 0.09 | NS |
| Cardiac output (in mL/min) |
15.3 ± 3.4 | 14.0 ± 1.3 | NS | 13.6 ± 0.4 | 13.2 ± 0.8 | NS | NS |
Values are represented as means ± SEM. *0.01 < p < 0.05, high-fat diet fed in obesity-prone (OP) vs. normal chow fed in obesity-resistant (OR) rats. ††0.001 < p < 0.01 12- vs. 4-month high-fat diet fed in obesity-prone (OP) rats. Relative left ventricular wall surface area was calculated as follows: (LVAd sax EPI – LVAd sax PM)/(LVAd sax EPI), where LVAd sax EPI means left ventricular epicardial short-axis area at the papillary muscle tip level at end-diastole, and LVAd sax PM, left ventricular endocardial short-axis at the papillary muscle tip level at end diastole and was used to estimate left ventricular hypertrophy. Stroke volume was calculated as follows: (LVOT VTI x aortic cross-sectional area), where LVOT VTI means left ventricular outflow tract velocity time integral (used as a measure of cardiac systolic function and cardiac output) and the aortic cross-sectional area (in mm). Cardiac output was calculated with the formula (stroke volume x heart rate). LV means left ventricular; LVEF, left ventricular ejection fraction; FS, fractional shortening; LVIDd, left ventricular internal diastolic dimension (indexed for tibia length); LVRWT, relative wall thickness; OR, obesity-resistant rats; OP, obesity-prone rats; NS, not significant.