Cyclooxygenase isoforms and prostaglandin E2 receptors in the ductus arteriosus

Indomethacin administered early in the postnatal period results in reduced glomerular number in the adult rat

Indomethacin and ibuprofen are administered to close a patent ductus arteriosus (PDA) during active glomerulogenesis. Light and electron microscopic glomerular changes with no change in glomerular number were seen following indomethacin and ibuprofen treatment during glomerulogenesis at 14 days after birth in a neonatal rat model. This present study aimed to determine whether longstanding renal structural changes are present at 30 days and 6 mo (equivalent to human adulthood). Rat pups were administered indomethacin or ibuprofen antenatally on days 18-20 (0.5 mg·kg(-1)·dose(-1) indomethacin; 10 mg·kg(-1)·dose(-1) ibuprofen) or postnatally intraperitoneally from day 1 to 3 or day 1 to 5 (0.2 mg·kg(-1)·dose(-1) indomethacin; 10 mg·kg(-1)·dose(-1) ibuprofen). Control groups received no treatment or normal saline intraperitoneally. Pups were killed at 30 days of age and 6 mo of age. Tissue blocks from right kidneys were prepared for light and electron microscopic examination, while total glomerular number was determined in left kidneys using unbiased stereology. Eight pups were included in each group from 14 maternal rats. At 30 days and 6 mo, there were persistent electron microscopy abnormalities of the glomerular basement membrane in those receiving postnatal indomethacin and ibuprofen. There were no significant light microscopy findings at 30 days or 6 mo. At 6 mo, there were significantly fewer glomeruli in those receiving postnatal indomethacin but not ibuprofen (P = 0.003). In conclusion, indomethacin administered during glomerulogenesis appears to reduce the number of glomeruli in adulthood. Alternative options for closing a PDA should be considered including ibuprofen as well as emerging therapies such as paracetamol.

Maturation of the contractile response of the Emu ductus arteriosus

The avian embryo has a pair of ductus arteriosi that allow the blood to bypass the pulmonary circulation prior to the initiation of lung ventilation. Our objective was to characterize the factors regulating DA tone during the later stages of development in the emu embryo. We examined in vitro the reactivity of the emu ductus from day 39 through 49 of a 50-day incubation. Steady state tension was not altered by the COX inhibitor indomethacin or the nitric oxide synthase inhibitor L-NAME. However, prostaglandin E(2) (PGE(2)) produced a significant relaxation. Norephinephrine and U-46619 produced strong significant contractions in the emu DA and the adrenergic response matured with development. The contractile response to oxygen matured as the embryo developed with significant oxygen-induced contraction on days 45 and 49, but not on day 39 of incubation. The Kv channel inhibitor 4-aminopyridine induced the contraction of the day 48-49 ductus of similar magnitude as the oxygen-induced contraction. The oxygen-induced contraction was reversed by the reducing agent DTT and the electron transport chain inhibitor rotenone. These results suggest that while the emu DA responds to PGE(2), locally produced PGE(2) are not the important regulators of vessel tone. Additionally, relaxation upon addition of the mitochondria electron transport chain inhibitor rotenone suggests that the mitochondria might be acting as vascular oxygen sensors in this system through the production of reactive oxygen species to stimulate the oxygen-induced contraction in a similar fashion to mammals.

Severe ductal constriction in the third-trimester fetus following maternal self-medication with nimesulide

OBJECTIVE

This was a multicenter series of 10 cases of constriction of the fetal ductus arteriosus occurring after maternal ingestion of one or two oral doses of nimesulide, which led to emergency delivery in four cases.

METHODS

The computerized databases of three referral centers were searched for all cases of ductal constriction detected during the last 8 years in association with maternal ingestion of nimesulide. Ten cases were retrieved and represent the study population. The following variables were analyzed: gestational age at diagnosis, reason for nimesulide ingestion, total nimesulide dose, time interval between drug intake and ultrasound examination, indication for echocardiography, presence of right ventricular hypertrophy, presence of tricuspid valve regurgitation, ductal systolic and diastolic peak velocities, ductal pulsatility index, signs of fetal heart failure, pregnancy and feto-neonatal outcome, and ductal status at neonatal echocardiography.

RESULTS

Nimesulide ingestion was the result of self-medication in all cases. The mean gestational age at diagnosis was 36.3 weeks and the mean time interval between nimesulide intake and echocardiographic examination was 2.9 days. The five cases with ductal peak velocities > 2.5 m/s showed right ventricular dysfunction with significant tricuspid regurgitation. At echocardiography performed immediately after birth, the ductus appeared closed in all cases and two neonates showed persistent pulmonary hypertension requiring intermittent positive pressure ventilation and nitric oxide therapy for 1 week.

CONCLUSIONS

Although the true incidence of the adverse effect of nimesulide ingestion during pregnancy cannot be deduced, we believe that patients and their clinicians should be alerted to the possibility that clinically significant ductal constriction may follow maternal self-medication with just one or two oral doses of nimesulide, at least if the drug is taken near term.