The effect of age and DR on ISO-stimulated adenylyl cyclase
| 6 month | 12 month | 24 month | ||||
|---|---|---|---|---|---|---|
| AL | DR | AL | DR | AL | DR | |
| E max | 11.0 ± 0.7 | 10.9 ± 0.4 | 7.0 ± 0.3* | 9.1 ± 0.3*** | 5.2 ± 0.3** | 8.2 ± 0.5*** |
| EC50(μM) | 0.25 ± 0.04 | 0.17 ± 0.03 | 0.22 ± 0.04 | 0.16 ± 0.02 | 0.18 ± 0.05 | 0.20 ± 0.04 |
Maximal response (Emax) (adenylyl cyclase activity, pmol/min/mg protein) and EC50 (μM) for ISO-stimulated adenylyl cyclase activity in cardiac ventricular membranes prepared from 6-, 12- and 24-month-old AL and DR rats. Data are presented as the mean ± S.E.M. of five to six rats in each age and diet group.
* Significantly less than 6-month-old AL rats (ANOVA, P < .05).
** Significantly less than 6- and 12-month-old AL rats (ANOVA, P < .05).
*** DR rats significantly greater than AL rats within the same age groups (ANOVA, P < .05).