Table 1.

Maximal internal diameters (in μm) for FA and arterioles in young and old mice

	Young		Old
Vessel Branch	SNP	ACh	SNP	ACh
FA	57 ± 2	60 ± 2*	61 ± 4	62 ± 5
1A	50 ± 2	51 ± 2	55 ± 5	56 ± 5
2A	35 ± 3	35 ± 2	44 ± 3	44 ± 4
3A	23 ± 2	23 ± 1	32 ± 3	31 ± 4

Values are means ± SE; n = 5 per group. One vessel from each branch order was studied in each gluteus maximus muscle (GM) preparation. Maximal internal diameters were obtained during superfusion with 10⁻⁴ M sodium nitroprusside (SNP) and with 10⁻⁵ M ACh. Young, 4-mo-old male C57BL/6 mice; Old, 24-mo-old male C57BL/6 mice; FA, feed arteries; 1A, first-order arteriole; 2A, second-order arteriole; 3A, third-order arteriole.

^*P < 0.05, ACh vs. SNP.