Effects of intravascular infusions of plasma on placental and systemic blood flow in fetal sheep.
Six singleton fetal sheep of 118-122 days gestational age were instrumented with flow sensors on the brachiocephalic artery, the postductal aorta, and the common umbilical artery and with arterial and venous intravascular catheters. At 125-131 days of gestation, we started week-long continuous recordings of flows and pressures. After control measures had been obtained, the fetuses were given continuous intravenous infusions of adult sheep plasma at an initial rate of 229 ml/day. After 1 wk of infusion, fetal plasma protein concentrations had increased from 34 to 78 g/l, arterial and venous pressures had increased from 42 to 64 and from 2.7 to 3.7 mmHg, and systemic resistance (exclusive of the coronary bed) had increased from 0.047 to 0.075 mmHg.min(-1).ml(-1), whereas placental resistance had increased from 0.065 to 0.111 mmHg.min(-1).ml(-1). Fetal plasma renin activities fell as early as 1 day after the start of infusion and remained below control (all changes P < 0.05). All flows decreased slightly although these decreases were not statistically significant. Thus the increase in arterial pressure was entirely due to an increase in systemic and placental resistances.
Giraud
George D
GD
Dept. of Physiology & Pharmacology, Oregon Health and Sciences University, Portland, OR 97239, USA. giraudg@ohsu.edu
Faber
J Job
JJ
Jonker
Sonnet S
SS
Davis
Lowell
L
Anderson
Debra F
DF
D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology; D005260:Female; D005333:Fetus / Q000098:blood supply* / Q000502:physiology; D006973:Hypertension / Q000209:etiology / Q000503:physiopathology; D010920:Placenta / Q000098:blood supply*; D021041:Placental Circulation / Q000502:physiology*; D010949:Plasma / Q000502:physiology*; D011247:Pregnancy; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D012083:Renin / Q000097:blood; D012756:Sheep; D014469:Umbilical Arteries / Q000502:physiology; D014655:Vascular Resistance / Q000502:physiology
D012083:Renin