Forskolin dilates the maternal ovine placental vascular bed.
We have examined the placental vascular responses to forskolin in 8 near-term sheep. The drug was administered for 5 min at 1 ml/min of 10(-3) M forskolin via a retrograde uterine arterial catheter. Blood flows were measured with radioactive microspheres. Forskolin increased the nonplacental uterine blood flow from 0.318 +/- 0.031 (SEM) to 0.738 +/- 0.071 ml/min per g of tissue, P less than 0.001. The nonplacental uterine vascular resistance decreased from 308 +/- 26 to 132 +/- 12 mmHg/ml/min per g, P less than 0.001. Forskolin increased the placental blood flow from 1.8 +/- 0.18 to 2.08 +/- 0.16 ml/min per g of tissue, P less than 0.05. The placental vascular resistance decreased from 54.7 +/- 5.1 to 45.9 +/- 3.7 mmHg/ml/min per g, P less than 0.03. In the same animals we then infused angiotensin II at 5 micrograms/min via the jugular vein to induce placental vasoconstriction. In this series, the forskolin increased the nonplacental uterine blood flow from 0.141 +/- 0.016 to 0.485 +/- 0.079 ml/min per g of tissue, P less than 0.001, and the uterine vascular resistance decreased from 968 +/- 104 to 283 +/- 36 mmHg/ml/min per g, P less than 0.001. The placental blood flow increased from 2.08 +/- 0.012 to 2.69 +/- 0.17 ml/min per g of tissue, P less than 0.01 and placental vascular resistance decreased from 61.9 +/- 4.4 to 46.0 +/- 3.7 mmHg/ml/min per g, P less than 0.001.(ABSTRACT TRUNCATED AT 250 WORDS)
Rankin
J H
JH
Department of Physiology, University of Wisconsin, Madison.
Landauer
M
M
Tian
Q
Q
Neaves
N
N
Phernetton
T M
TM
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D005576:Colforsin / Q000494:pharmacology*; D011464:Epoprostenol / Q000494:pharmacology; D005260:Female; D010920:Placenta / Q000098:blood supply*; D011247:Pregnancy; D012756:Sheep; D014664:Vasodilation / Q000187:drug effects*
D000804:Angiotensin II; D005576:Colforsin; D011464:Epoprostenol