Effect of KSO, NPFF, and KP peptides on forskolin-stimulated ir-cAMP release from ND-7/23 cells. Cells were exposed to forskolin with KSO, NPFF, or KP peptides for 30 min prior to termination of the reaction with 0.1 M HCl. The effects of the NPFF receptor antagonist RF9 and the GPR-54 antagonist KP234 on KSO, NPFF, or KP peptide inhibition of forskolin-stimulated ir-cAMP release were also determined. Levels of ir-cAMP in the cell lysates were measured by EIA. Results are mean ± sem (). * versus forskolin alone; ^† versus KSO, NPFF, or KP peptide alone; one-way ANOVA.