sentence: The beads with and without cells were then transferred to 0.5-ml chambers and perifused with Krebs-Ringer medium containing 0.1 % BSA for 2.5 h at a flow rate of 0.8 ml / min and at 37 ° C. Fractions were collected in 1-min intervals and immediately assayed for ATP contents using an ATP bioluminescent assay kit ( Sigma ) in TD-20 / 20 Luminometer ( Turner Designs , Sunnyvale , CA ) .