Table 5.

The dB-cAMP-induced hyperpolarization of HepG2 cells is microtubule dependent

	Ratio of bile canaliculi to total cells
Control	1:13.7 ± 0.1
dB-cAMP	1:5.8 ± 0.8
Nocodazole	1:16.2 ± 1.4
dB-cAMP + nocodazole	1:15.7 ± 4.5

HepG2 cells were washed and incubated with or without 1 mM dB-cAMP, 33 μM nocodazole, or both in HBSS for 4 h at 37°C. When cells were incubated with both nocodazole and dB-cAMP, the cells were preincubated with nocodazole for 30 min in HBSS before the addition of dB-cAMP. After the incubation, cells were washed and double stained for actin and nuclei, using TRITC–phalloidin and Hoechst 33258, respectively, as described in MATERIALS AND METHODS. Cells were examined by fluorescence microscopy. For each condition, five random fields were scored for the total number of cells by counting nuclei and the total number of bile canaliculi, stained with actin. Each field contained 200–300 cells. Data represent the mean ± SEM of three independent experiments.