TABLE 3. Effects of PKA and PKC activation on A_2aAR-stimulated adenylyl cyclase activity.

Cells were treated for either 30 min or 24 hr in the presence of 0.3 unit/ml ADA and either 10 μM forskolin or 0.1% (v/v) ethanol vehicle (control). Cells were also treated for 30 min with ADA and either 1 μM phorbol 12-myristate 13-acetate (PMA) or 1 μM 4_α-phorbol, an inactive phorbol ester (PKC control). Membranes were then prepared for assay of adenylyl cyclase activity in the absence or presence of 10 μM NECA, with MgCl₂ present at final concentrations of either 10 mM (high [Mg²⁺]) or 1 mM (low [Mg²⁺]), as described in Experimental Procedures. Data are presented as means ± standard errors for three experiments.

	30 min				24 hr
	High [Mg2+]		Low [Mg2+]		High [Mg2+]		Low [Mg2+]
	Stimulationa	EC50	Stimulation	EC50	Stimulation	EC50	Stimulation	EC50
	Fold	μM	fold	μM	fold	μM	fold	μM
Control	8.7 ± 0.6	0.13 ± 0.04	11.5 ± 0.3	0.21 ± 0.03	11.6 ± 0.2	0.21 ± 0.06	11.5 ± 0.3	0.28 ± 0.05
10 μM Forskolin	9.7 ± 0.7	0.19 ± 0.04	11.2 ± 0.2	0.40 ± 0.11	11.5 ± 1.3	0.23 ± 0.08	11.2 ± 0.3	0.50 ±0.12
PKC control	8.3 ± 1.2	—b	14.3 ± 0.5	—	—	—	—	—
1 μM PMA	8.1 ± 1.1	—	15.9 ± 0.5	—	—	—	—	—

^aStimulation above basal.

^b—, not determined.