Table 2.
Inhibition of Bovine A1-Adenosine Receptors by Purine Isothiocyanate Derivatives (without Cleavable Chains) and the Stability of this Inhibition to Reagents for Later Use in Cleavage Reactiona
| inhibition (% of control) |
|||||
|---|---|---|---|---|---|
| concn (mM) |
m-DITC-XAC, 5 |
m-DITC-ADAC, 6 |
|||
| reagent | [3H]CPX | [3H]PIA | [3H]CPX | [3H]PIA | |
| none | 80 ± 4 (7) | 55 ± 7 (3) | 48 ± 8 (6) | 51 ± 4 (4) | |
| DTT | 5 | 82 ±4 (8) | 55 ± 4 (4) | 50 ± 4 (8) | 52 ± 11 (4) |
| DTT | 50 | 78,81 | nd | 52,58 | nd |
| H2NOH | 250 | 78 ± 3 (9) | 61 ± 8 (9) | 47 ± 6 (6) | 50 ± 12 (6) |
a
Data are means ± s.e.m. of three to nine experiments (n given in parentheses). After incubation with the isothiocyante derivative (5 or 6) at 37 °C, membranes were washed three times, incubated overnight with IBMX (200 μM) in the presence of the indicated reagent, and again washed three times with IBMX and twice for DTT or hydroxylamine treatment. Radioligand binding was carried out with 0.2 nM [3H]CPX (14) or 1 nM [3H]PIA (13). nd: not determined.