Age-related comparison of antagonist receptor-binding characteristics in F344 rat atria and ventricles
| A1-Receptors | β-Receptors | |||||
|---|---|---|---|---|---|---|
| Kd | Bmax | Specific Binding | Kd | Bmax | Specific Binding | |
| nM | fmol/mg | % | pM | fmol/mg | % | |
| Atria | ||||||
| Adult | 0.75 ± 0.1 | 22.5 ± 2.6 | 34.5 ± 4.5 | 8.3 ± 1.3 | 82.2 ± 7.6 | 85.4 ± 1.2 |
| Senescent | 0.56 ± 0.12-a | 35.1 ± 2.52-a | 47.7 ± 2.0 | 9.4 ± 0.8 | 65.9 ± 4.0 | 81.9 ± 1.9 |
| Ventricles | ||||||
| Adult | 0.97 ± 0.1 | 9.2 ± 0.8 | 38.3 ± 2.7 | 7.2 ± 0.7 | 68.6 ± 3.7 | 84.9 ± 0.8 |
| Senescent | 0.61 ± 0.042-b | 5.6 ± 0.62-b | 43.1 ± 2.9 | 7.5 ± 1.0 | 63.5 ± 3.1 | 84.7 ± 0.9 |
Values are mean ± S.E. (n = 4 and 6 for atrial and ventricular adenosine A1-receptor studies, respectively; n = 6 for atrial and ventricular β-adrenoceptor studies).