Dose-dependent effects of angiotensin II on the ovine fetal cardiovascular system.
The purpose of this experiment was to establish dose-response relationships for the effects of angiotensin II on arterial pressure, venous pressure, heart rate, and blood volume in the ovine fetus. Chronically catheterized fetal sheep at 132 +/- 1 (SE) days' gestational age were infused with angiotensin II at 4.8 +/- 1.1 (n = 7), 27.7 +/- 4.6 (n = 7), 102.2 +/- 16.7 (n = 6), or 239.0 +/- 30.9 (n = 4) ng/min/kg fetal body weight for 30 minutes. Fetal arterial pressure increased at the three highest doses. Fetal venous pressure, heart rate, and blood volume responded only at 102.2 and 239.0 ng/min/kg. At 239.0 ng/min/kg, arterial pressure increased by 17.7 +/- 1.6 mm Hg (p less than 0.00001), venous pressure increased by 1.5 +/- 0.3 mm Hg (p less than 0.0005), blood volume decreased by 7.8 +/- 2.2% (p less than 0.0001), and heart rate initially decreased by 14 +/- 4 beats/min, followed by an increase of 52 +/- 17 beats/min from control (p less than 0.0005) at the end of angiotensin II infusion. Thus this study shows that angiotensin II affected multiple fetal cardiovascular variables in a dose-dependent manner, suggesting that it is an important regulatory hormone for the entire fetal cardiovascular system.
Jones
O W
OW
Department of Reproductive Medicine, University of California, San Diego, La Jolla 92093-0802.
Cheung
C Y
CY
Brace
R A
RA
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001798:Blood Proteins / Q000187:drug effects; D001810:Blood Volume / Q000187:drug effects; D002245:Carbon Dioxide / Q000097:blood; D002319:Cardiovascular System / Q000187:drug effects*; D002713:Chlorine / Q000097:blood; D004305:Dose-Response Relationship, Drug; D005260:Female; D005312:Fetal Blood / Q000737:chemistry; D006340:Heart Rate, Fetal / Q000187:drug effects; D006400:Hematocrit; D006863:Hydrogen-Ion Concentration; D009994:Osmolar Concentration; D010100:Oxygen / Q000097:blood; D011188:Potassium / Q000097:blood; D011247:Pregnancy; D012044:Regression Analysis; D012756:Sheep; D012964:Sodium / Q000097:blood
D001798:Blood Proteins; D000804:Angiotensin II; D002245:Carbon Dioxide; D002713:Chlorine; D012964:Sodium; D011188:Potassium; D010100:Oxygen