Table 2.

Species differences in LV dimensions and function at baseline and under stress conditions

	Baseline			Dobutamine
	Mouse	NMR	Significance	Mouse	NMR	Significance
Heart rate, beats/min	461 ± 14	229 ± 10	<0.0001	600 ± 16	306 ± 13	<0.0001
Average diastolic wall thickness, mm	0.77 ± 0.03	0.87 ± 0.02	0.0198	0.77 ± 0.03	0.88 ± 0.02	0.0152
LV end-diastolic dimension, mm	3.67 ± 0.08	4.03 ± 0.24	N.S.	3.34 ± 0.09	3.74 ± 0.21	N.S.
LV end-systolic dimension, mm	2.27 ± 0.12	2.93 ± 0.24	0.0239	1.66 ± 0.08	2.08 ± 0.18	N.S.
Fractional shortening, %	39 ± 2	28 ± 2	0.0002	52 ± 2	46 ± 2	0.0345
Ejection fraction, %	57 ± 3	43 ± 2	0.0008	79 ± 1	75 ± 2	N.S.
Cardiac output, ml/min	14.9 ± 0.7	6.5 ± 0.4	<0.0001	21.7 ± 0.9	11.5 ± 1.1	<0.0001
Stroke volume, μl	34.4 ± 1.4	26.0 ± 1.4	0.001	34.9 ± 1.3	37.2 ± 3.6	N.S.

All values are means ± SE. LV, left ventricular. Sample sizes are n = 10 (5/sex) animals for each species. Significance is indicated by P values; N.S. denotes P > 0.05.