Effect of dexamethasone on pulmonary and renal angiotensin-converting enzyme concentration in fetal sheep during late gestation.
OBJECTIVE
The effect of dexamethasone on tissue angiotensin-converting enzyme (ACE) was investigated in fetal sheep.


METHODS
Pulmonary and renal ACE concentrations were measured in 16 sheep fetuses at between 127 and 131 days of gestation (term 145+/-2 days): 6 were untreated, whereas 10 were chronically catheterized and infused intravenously with either saline solution (0.9%, n=4) or dexamethasone (45-60 microg. kg(-1). d(-1), n=6) for the previous 2 days. The dexamethasone dose increased plasma dexamethasone to around one fifth of that measured in newborn human infants delivered after maternal dexamethasone treatment.


RESULTS
Over the period of infusion, arterial blood pressure increased significantly in the dexamethasone (+6.8+/-1.5 mm Hg, P<.05) but not saline-treated fetuses (+1.6+/-0.6 mm Hg). At delivery, pulmonary ACE in the dexamethasone-infused fetuses (1.24+/-0.26 nmoles hippurate. min(-1). mg protein(-1)) was significantly greater than in the control fetuses (0.50+/-0.07 nmoles. min(-1). mg protein(-1), P<.005); renal ACE was unchanged by dexamethasone treatment. Overall, pulmonary ACE and blood pressure were correlated on the last day of infusion (r=0.70, P<.05).


CONCLUSIONS
The rise in pulmonary ACE seen in dexamethasone-treated sheep fetuses may contribute, in part, to the glucocorticoid-induced increase in blood pressure.
Zimmermann
Heiner
H
Department of Physiology, University of Cambridge, Downing Street, Cambridge CB2 3EG, United Kingdom.
Gardner
David S
DS
Jellyman
Juanita K
JK
Fowden
Abigail L
AL
Giussani
Dino A
DA
Forhead
Alison J
AJ
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002245:Carbon Dioxide / Q000097:blood; D003907:Dexamethasone / Q000494:pharmacology*; D005260:Female; D005333:Fetus / Q000378:metabolism / Q000502:physiology; D005865:Gestational Age; D005938:Glucocorticoids / Q000494:pharmacology*; D007668:Kidney / Q000196:embryology*; D008168:Lung / Q000196:embryology*; D009994:Osmolar Concentration; D010100:Oxygen / Q000097:blood; D007703:Peptidyl-Dipeptidase A / Q000378:metabolism*; D011247:Pregnancy; D012756:Sheep
D005938:Glucocorticoids; D002245:Carbon Dioxide; D003907:Dexamethasone; D007703:Peptidyl-Dipeptidase A; D010100:Oxygen