Fig. 5.

Ductus contractility in the newborn mouse after genetic and/or prolonged pharmacological COX inhibition in utero. A: newborn pups born to dams with chronic COX-1 (SC560), COX-2 (SC236), or combined COX inhibitors were placed in 80% oxygen for 4 h after birth. Vessel dimensions are expressed as a ratio of DA and AO diameters. Chronic COX inhibition on days 11–14 of gestation (n = 20, 7 litters) did not alter ductus closure after birth, whereas pups with COX-1 (n = 12, 4 litters), COX-2 (n = 23, 13 litters), or combined COX inhibition (n = 29, 11 litters) on days 15–19 of gestation had delayed closure of the ductus compared with controls (n = 12, 4 litters). B: targeted deletion of COX-1 (n = 11, 4 litters) had minimal effect on ductus closure after birth, whereas COX-2 deletion (n = 20, 8 litters) and COX-1/COX-2 double-null pups (n = 12, 6 litters) had a significant delay in ductal closure compared with controls (n = 12, 4 litters). Closure of the ductus of COX-1 null pups chronically exposed to COX-2 inhibitor in utero (n = 16, 6 litters) was also significantly delayed. KO, knockout. *P < 0.05 compared with untreated newborns at 4 h of age.