Table 4.

Electrocardiographic evaluation of cardiac conduction parameters in aging female F344xBN rats (mean ± SEM)

EKG Measurements	6 months	26 months	30 months
VAT	0.036 ± 0.0013	0.044 ± 0.0010*	0.046 ± 0.0007*
ST interval	0.055 ± 0.0035	0.080 ± 0.0018*	0.073 ± 0.0013*
T amplitude	0.090 ± 0.0065	0.123 ± 0.0071*	0.098 ± 0.0080†
QRS interval	0.055 ± 0.0010	0.066 ± 0.0013*	0.070 ± 0.0005*†
QT interval	0.110 ± 0.0035	0.146 ± 0.0023*	0.143 ± 0.0012*
PR interval	0.035 ± 0.0027	0.033 ± 0.0015	0.032 ± 0.0010
T duration	0.055 ± 0.0035	0.080 ± 0.0018*	0.073 ± 0.0013*
T–T interval	0.217 ± 0.0034	0.217 ± 0.0032	0.218 ± 0.0050
R + S amplitude	0.321 ± 0.0105	0.280 ± 0.0161	0.276 ± 0.0247
S amplitude	−0.009 ± 0.0061	−0.007 ± 0.0049	−0.029 ± 0.0121
R amplitude	0.035 ± 0.0027	0.033 ± 0.0015	0.032 ± 0.0010
Q amplitude	−0.005 ± 0.0019	−0.014 ± 0.0024*	−0.018 ± 0.0017*
P amplitude	0.006 ± 0.0052	0.037 ± 0.0018*	0.037 ± 0.0020*
P duration	0.035 ± 0.0027	0.033 ± 0.0015	0.032 ± 0.0010
Mean electrical axis	34.41 ± 5.99	63.13 ± 4.86*	63.26 ± 3.72*

KG amplitudes measured on Lead II axis of 6-month-old animals; 26-month-old animals; 30-month-old animals

*p < 0.05, significantly different from 6-month-old animals

^† p < 0.05, significantly different from 26-month-old animals