Alpha-atrial natriuretic peptide-induced attenuation of vasoconstriction in the fetal circulation of the human isolated perfused placenta.
In order to examine the effect of alpha-ANP on fetal placental vascular tone, single placental lobules were bilaterally perfused and fetal inflow pressure recorded. The placental vasculature was sub-maximally pre-constricted by infusion of the nitric oxide synthase inhibitor N omega-nitro-L-arginine (NOLA) or the thromboxane A2-mimetic U46619. In the presence of continuous infusion of 59.3 mumol/l NOLA, producing a mean pressure increase of 43.7 +/- 1.7 mmHg (n = 8, mean +/- SEM), alpha-ANP (10.7 to 325 nmol/l) produced significant pressure decreases (P < 0.05). In separate experiments (U46619 was either infused at concentrations (4.8 to 21.4 nmol/l) to produce a mean pressure increase (50.1 +/- 2.6 mmHg, n = 10) similar to that produced by NOLA infusion or was infused at a concentration (28.5 nmol/l) that produced a significantly higher pressure increase (104 +/- 15 mmHg), infusion of 1 mumol/l alpha-ANP significantly reduced perfusion pressure. However, 100 nmol/l alpha-ANP or less had no significant effect (n = 4-7). These results indicate that alpha-ANP attenuates NOLA-induced and U46619-induced vasoconstriction in the human placenta, but at concentrations higher than those in fetal or maternal plasma.
Stebbing
P N
PN
Department of Perinatal Medicine, Royal Women's Hospital, Melbourne, Australia.
Gude
N M
NM
King
R G
RG
Brennecke
S P
SP
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D009320:Atrial Natriuretic Factor / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007261:Infusions, Intra-Arterial; D019335:Nitroarginine / Q000494:pharmacology; D010477:Perfusion; D010920:Placenta / Q000098:blood supply* / Q000187:drug effects / Q000502:physiology; D011247:Pregnancy; D011312:Pressure; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology; D013928:Thromboxane A2 / Q000031:analogs & derivatives / Q000494:pharmacology; D014655:Vascular Resistance / Q000187:drug effects / Q000502:physiology*; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D004791:Enzyme Inhibitors; D011450:Prostaglandin Endoperoxides, Synthetic; D014662:Vasoconstrictor Agents; D019335:Nitroarginine; D013928:Thromboxane A2; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D009320:Atrial Natriuretic Factor