Table 5.

Agonist responses to fluorescent NECA analogues at the adenosine A₁ receptor

Agonist	Gi (log IC50)	n	Gs (log EC50)	n	+PTX
					Gs (log EC50)	Gs EMAX(fold increase)	n	Log KD−Log IC50
NECA	−8.43 ± 0.04	15	−6.13 ± 0.03	15	−6.37 ± 0.04	1.81 ± 0.07	13	1.92
APrEA-X-BY630	−8.21 ± 0.11	8	−6.18 ± 0.13	8	−6.62 ± 0.13	1.67 ± 0.06	7	2.40
ABEA-X-BY630	−7.92 ± 0.06	8	−6.38 ± 0.17	6	−6.40 ± 0.06	1.44 ± 0.03	8	2.03
APEA-X-BY630	−7.97 ± 0.07	8	−6.23 ± 0.13	5	−6.58 ± 0.06	1.41 ± 0.06	11	1.93
AOEA-X-BY630	−7.32 ± 0.09	6	NS		>−5			1.28
ADOEA-X-BY630	−7.20 ± 0.17	6	−5.79 ± 0.11	4	−5.97 ± 0.07	1.31 ± 0.06	4	0.97
ABEA-dansyl	−5.95 ± 0.09	7	NS		>−5		7
ABEA-AO-dansyl	−6.64 ± 0.08	10	NS		>−6		7
AUEA-dansyl	−7.08 ± 0.08	8	NS		NS		7	2.25
ABEA-X-Texas Red	−6.05 ± 0.17	3	NS	3	NS		3
ABEA-EVOBlue 30	−5.45 ± 0.11	3	NS	3	NS		3
ABEA-Cy5	−5.27 ± 0.35	3	NS	3	NS		3
ABEA-BYFL	−6.03 ± 0.09	7	NS	7	NS		7
ABEA-X-BYFL	−6.57 ± 0.08	7	NS	7	>−5		7

Values represent mean ± SEM of n separate experiments. Values are log (IC₅₀) and log (EC₅₀) determinations from the agonist-mediated inhibition (G_i) or enhancement (G_s), respectively, of forskolin-stimulated CRE-reporter gene activity. In some experiments (+PTX), cells were incubated overnight with PTX (100 ng·mL⁻¹), and under these conditions, only a stimulatory response (G_s) was obtained. An indication of agonist efficacy is provided by the difference between log IC₅₀ values and the log K_D values reported for each agonist in Table 2.

ABEA, N⁶-(4-aminobutyl)-5′-ethylamino-5′-oxo-5′-deoxyadenosine; ADOEA, N⁶-(8-amino-3,6-dioxaoctyl)-5′-ethylamino-5′-oxo-5′-deoxyadenosine; AEAO, 8-(2-aminoethylamino)-8-oxooctanoyl; AO, 8-aminooctanoyl; AOEA, N⁶-(8-aminooctyl)-5′-ethylamino-5′-oxo-5′-deoxyadenosine; APEA, N⁶-(5-aminopentyl)- 5′-ethylamino-5′-oxo-5′-deoxyadenosine; APrEA, N⁶-(3-aminopropyl)-5′-ethylamino-5′-oxo-5′-deoxyadenosine; AUEA, N⁶-(11-aminoundecyl)-5′-ethylamino-5′-oxo-5′-deoxyadenosine; PTX, Pertussis toxin; NECA, adenosine-5′-N-ethyluronamide; NS, no stimulation; X, 6-aminohexanoyl.