Figure 2

Pretreatment of chromaffin cells with DETA/NO causes a time-dependent down-regulation of cGMP accumulation in response to subsequent NO stimulation (A) or YC-1 stimulation (B) without affecting their viability (C). Bovine chromaffin cells were pretreated with 50 μmol/LDETA/NO for the times indicated. Cells where then incubated with 0.5 mmol/L IBMX for 30 min and stimulated with 1 μmol/L DEA/NO or 250 μmol/L YC-1 for 10 min. cGMP was determined by radioimmunoassay as described in Methods. 1C. Cells were incubated with 50 μmol/L DETA/NO for 48 hours and then incubated for 30 min in Locke's solution in the presence of the viability/cytotoxicity probes EthD-1 and calcein-AM. Images were taken under a fluorescence microscope using an excitation optical filter and two different emission filters: a 530 nm bandpass filter for calcein (upper panels) and a 590 nm longpass filter for EthD-1 (lower panels).