Table 1.

Comparison of Different Parameters in Young, Middle-aged, and Old Rats

Parameter	Young	Middle-aged	Old	Significance level
Weight (g)	305 ± 8*	537 ± 7*	514 ± 20*	*P < 0.0001 for Y vs. M and Y vs. O
Systolic RR (mmHg)	121 ± 4	117 ± 4	117 ± 2	NS
Heart rate (bpm)	334 ± 13	323 ± 14	344 ± 13	NS
Maximal relaxations (%)
Ach	−96 ± 2*	−89 ± 2*	−62 ± 3*	*P < 0.0001 for Y vs. O and M vs. O
A23187	−76 ± 1*	−74 ± 4*	−47 ± 4*	*P < 0.0001 for Y vs. O and M vs. O
SNP	−111 ± 2	−107 ± 1	−105 ± 1	NS
Maximal NO release (nmol/liter)	690 ± 50*	490 ± 70*	200 ± 30*	*P < 0.0001 for Y vs. O
				*P < 0.001 for M vs. O
				*P < 0.01 for M vs. Y
NOS activity (pmol/min/mg)
Total	120 ± 13*	−	216 ± 26*	*P < 0.01
eNOS	23 ± 10**	−	144 ± 14**	**P < 0.001
iNOS	97 ± 15	−	72 ± 12	NS
Superoxide (cpm/mg dry wt)
Basal	2,302 ± 323*	2,145 ± 220*	6,058 ± 445*	*P < 0.0001 for Y vs. O and M vs. O
Stimulated	82,495 ± 6,033**	108,439 ± 2,612	175,058 ± 36,080**	**P < 0.01

Y, young; M, middle-aged; O, old; RR, blood pressure; bpm, beats per minute.