Table 3

CPA inhibition of the specific binding of [³H]DPCPX in semipurified atrial and ventricular membrane preparations from 6- and 24-month-old F344 rats

	K_i(nM)^3-a	Site 1		Site 2		F	P
	K_i(nM)^3-a	%^3-b	K_i(nM)^3-a	%^3-b	K_i(nM)^3-a	F	P
Atria
Adult (n = 5)	8.93 (5.04, 15.78)	63.7 ± 0.13	0.83 (0.29, 2.37)	36.3 ± 0.13	146 (28.3, 755.5)	0.29	0.596
Senescent (n = 4)	8.36 (3.01, 22.96)	74.1 ± 0.03^3-c	1.71 (0.71, 4.87)	25.9 ± 0.03^3-c	229 (73.8, 5898)	5.5	0.03
Ventricles
Adult (n = 7)	6.69 (3.75, 12.2)	76.6 ± 0.04	1.1 (0.47, 2.54)	23.4 ± 0.04	345 (46.3, 2595)	13.47	0.003
Senescent (n = 7)	10.9 (3.35, 35.9)	56.1 ± 0.05^3-c	0.68 (0.39, 1.17)	43.9 ± 0.05^3-c	112 (18.5, 680.5)	0.68	0.42

↵3-a Data shown are mean and 95% CI.
↵3-b Data shown are mean ± S.E.
↵3-c Significantly different than corresponding value in 6-month-old rats (P < .05).