Table 3.
Log KD values from antagonism of NECA-mediated inhibition (Gi) and enhancement (Gs) of forskolin-stimulated CRE reporter gene responses
| Antagonist |
Log KD |
n |
Log KD |
n | +PTX |
n |
|---|---|---|---|---|---|---|
| Gi | Gs | Gs | ||||
| XAC | −7.86 ± 0.05 | 14 | −7.92 ± 0.04 | 14 | −7.99 ± 0.05 | 6 |
| XAC-X-BY630 | −6.92 ± 0.09 | 9 | −6.94 ± 0.06 | 12 | −7.14 ± 0.05 | 6 |
| XAC-X-Texas Red | −6.00 ± 0.15 | 6 | −6.09 ± 0.08 | 7 | −6.31 ± 0.10 | 4 |
| XAC-dansyl | −7.37 ± 0.08 | 8 | −7.31 ± 0.03 | 7 | −7.22 ± 0.17 | 7 |
| XAC-AO-dansyl | −7.43 ± 0.07 | 6 | −7.42 ± 0.09 | 6 | −7.02 ± 0.10 | 6 |
| XAC-AHH-dansyl | −7.14 ± 0.15 | 5 | −7.30 ± 0.10 | 5 | −6.99 ± 0.09 | 6 |
Values represent mean ± SEM of n separate experiments. KD values were determined from the parallel shifts obtained in the inhibitory (Gi) and stimulatory (Gs) phases of the NECA concentration response curves. In some experiments (+PTX), cells were incubated overnight with PTX (100 ng·mL–1), and under these conditions, only a stimulatory response (Gs) was obtained. No antagonism was seen with XAC-AEAO-BYFL, XAC-EVOBlue 30 or XAC-Cy5 at concentrations up to 1 µM.
AEAO, 8-(2-aminoethylamino)-8-oxooctanoyl; AO, 8-aminooctanoyl; CRE, cyclic AMP response element; NECA, 5′(N-ethylcarboxamido)adenosine; PTX, Pertussis toxin; X, 6-aminohexanoyl; XAC, xanthine amine congener.