Table 1. Dose-dependent effects of AICA riboside on AMPK activity, ZMP concentration and JO₂ in isolated rat hepatocytes.

Hepatocytes isolated from 24 h-starved rats were incubated at 37°C in a Krebs/bicarbonate medium supplemented with 20 mM lactate, 2 mM pyruvate and 4 mM octanoate and in the presence or absence of the indicated concentrations of AICA riboside. After 30 min of incubation, the antimycin-sensitive JO₂ was measured before and after the successive addition of 6 μg/ml oligomycin, 100 μM DNP, 0.15 μg/ml antimycin and 1 mM TMPD plus 5 mM ascorbate. The oligomycin-sensitive JO₂ was calculated by subtracting the oligomycin-insensitive JO₂ from the basal JO₂. In separate experiments, samples of cell suspension were removed for the AMPK assay and determination of intracellular ZMP concentrations, as described in the Materials and methods section. The results are expressed as means±S.E.M. (n=4). *P<0.05 compared with no addition.

			JO2 (μmol O2·min−1·g of dry hepatocytes−1)
AICA riboside (μM)	ZMP (μmol·g of dry hepatocytes−1)	AMPK activity (μmol·g of dry hepatocytes−1)	Basal	Oligomycin	Oligomycin-sensitive	DNP	TMPD/a
0	<0.1	123±6	26.4±1.3	9.9±0.8	16.5±1.0	44.3±3.8	108.2±7.1
50	1.2±0.1*	145±7*	22.4±1.7*	10.0±0.3	12.3±1.4*	40.7±1.3	108.0±2.0
100	2.1±0.1*	175±7*	23.1±1.2*	9.0±0.8	14.1±0.9*	41.2±4.8	105.9±6.2
250	6.1±0.7*	217±8*	20.9±0.9*	9.9±1.2	11.0±0.5*	42.0±5.9	99.6±8.7
500	10.5±1.3*	245±8*	18.5±0.9*	8.8±0.7	9.7±0.8*	38.8±5.3	99.9±8.8
1000	15.0±1.4*	220±12*	18.1±0.4*	8.5±1.1	9.6±1.0*	38.6±5.7	101.9±6.7
2500	17.0±1.0*	211±9*	16.5±1.0*	7.5±0.9*	9.0±0.6*	35.2±5.7*	97.7±6.0