Relative contribution of ecto-5′
NT and NSAP to Ado regulation. A-C, simulated (
lines) and experimental (
symbols) time courses of Ado accumulation from 0.1 to 10 μ
m ATP under control conditions and after blocking ecto-5′-NT (
solid red line) or NSAP (
solid blue line) activities. For NSAP, simulations were run by blocking the parameters regulating AMP (NSAP (AMP)) (
dashed blue line) or all nucleotides (NSAP (all)) (
solid blue line). Experimental data using HBE cultures were incubated with 0.1-10 μ
m ATP, without/with an inhibitor of ecto-5′-NT (10 m
m concanavalin A) (
open red triangle), or NSAP (all) (10 m
m levamisole) (
open blue box) (
n = 6; S.E. < 10% of mean).
D, simulated (
solid black box) and experimental (
solid red box) delay to the accumulation of 0.3 μ
m Ado from 1 to 1000 μ
m ATP. Simulations also compared the impact of blocking ecto-5′-NT with (
striped box) or without (
open box) feed-forward inhibition (

,

block; Table 1, column C).
E, simulated (
solid black box) and experimental (
solid blue box;
n = 5,
p < 0.05) impact of blocking NSAP (all) on the delay to reach 0.3 μ
m Ado (fold from controls in
D). Simulated impact of blocking both NSAP (all) and feed-forward inhibition (
striped black box) is shown.
F, simulated impact of blocking NSAP (all) (
solid black box) or ecto-5′-NT (
open box) on the steady-state profile. Experimental block of NSAP (all) (
solid blue box) or ecto-5′-NT (
solid red box) was obtained by measuring nucleotide levels before/after incubating cultures with the inhibitors (
n = 5,
p < 0.05).