Relaxant effects of hexosamines on isolated small human placental arteries.
Wharton's jelly contains large amounts of hyaluronic acid, and glucosamine is an important constituent of this macromolecule. In order to evaluate the placental vascular effects of this aminosugar, small chorionic and stem villous arteries were dissected from placental specimens obtained at normal term vaginal deliveries (n = 15). Ring preparations were mounted in organ baths, and isometric wall tensions were measured. Glucosamine and its epimer galactosamine (5 X 10(-4) to 10(-2) M) produced marked relaxation of contractions induced by PGF2 alpha (10(-5) M) in both chorionic and stem villous arteries. The effect was unchanged after pretreatment with atropin, propranolol and indomethacin. The relaxant effect of the neutral sugar mannose was less pronounced compared with that of the hexosamines. Total tissue concentrations of placental hexosamines have been reported within the range needed to produce placental vascular relaxation in the present study. However, the major part of these compounds is integrated in macromolecules, and the tissue level of free hexosamine is probably far below the total concentrations. Accordingly, the effects of hexosamines demonstrated in the present study might not be of physiological importance in the regulation of fetal placental medial smooth muscle tension.
Department of Obstetrics and Gynaecology, University of Aarhus, Denmark.
N
N
Uldbjerg
J
J
Allen
S
S
Maigaard
A
A
Forman
D001158:Arteries / Q000187:drug effects; D005260:Female; D005688:Galactosamine / Q000494:pharmacology*; D005944:Glucosamine / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D008358:Mannose / Q000494:pharmacology; D010920:Placenta / Q000098:blood supply / Q000187:drug effects*; D014661:Vasoconstriction / Q000187:drug effects*
D005688:Galactosamine; D005944:Glucosamine; D008358:Mannose