Table 2.

Diaphragm twitch characteristics and maximum force from 4- and 12-wk-old mice

	4-wk-old		12-wk-old
Diaphragm	25 IU/kg	10,000 IU/kg	25 IU/kg	10,000 IU/kg
Po, N/cm2	14.8 ± 0.98*	21.6 ± 0.89	18.3 ± 0.98	19.5 ± 0.98
Pt, N/cm2	2.89 ± 0.28	3.93 ± 0.14	3.28 ± 0.38	3.63 ± 0.22
TPT, ms	24.4 ± 1.27	27.5 ± 1.01	23.1 ± 0.91	25.8 ± 1.71
RT1/2, ms	55.0 ± 5.0	66.3 ± 7.31	57.8 ± 4.46	53.8 ± 3.80

Data are from animals fed diets containing 25 or 10,000 IU/kg of vitamin D for 6 wk. Mice were started on the vitamin D diets beginning at 4 and 12 wk of age (n = 5/group, 20 total). Values are means ± SE. Po, maximal tetanic force; Pt, peak twitch force; TPT, time to peak tension; RT_1/2, time it takes for peak tetanic force to decrease by 50%.

^*Significantly different from 4-wk 10,000 IU/kg (P = 0.001).