Absence of relaxation to lactate in human placental vessels of pregnancies with severe preeclampsia.
OBJECTIVE
Our objective was to determine whether the observed relaxation to lactate and other agents in placental vessels of normal pregnancies is altered in severe preeclampsia.


METHODS
Isolated placental arteries and veins from women with severe preeclampsia and uncomplicated term pregnancies were precontracted with prostaglandin F2 alpha under 5% oxygen and 5% carbon dioxide with the balance nitrogen (Po2 35 to 38 torr) and then exposed to lactate (1 to 10 mmol/L, pH 7.4, n = 8 to 15), arachidonic acid (0.01 to 10 mumol/L, n = 6 to 13), nitroglycerin (1 nmol to 1 mumol/L, n = 4 to 12), or forskolin (0.01 to 10 mumol/L, n = 6 to 9). The response to lactate was also examined in placental vessels from appropriate-for-gestational-age preterm deliveries (n = 8) for comparison with a similar group with severe preeclampsia (n = 8). The t test and analysis of variance statistics were used.


RESULTS
Relaxation to lactate was markedly inhibited in both placental arteries and veins of women with severe preeclampsia compared with vessels from uncomplicated term or preterm pregnancies. Responses to the other relaxing agents were not altered in the severely preeclamptic vessels.


CONCLUSIONS
In severe preeclampsia absence of lactate-induced dilatation of placental vessels may contribute to the fetal complications associated with impaired blood flow and vasospasm.
Figueroa
R
R
Department of Physiology, New York Medical College, Valhalla 10595, USA.
Martinez
E
E
Fayngersh
R P
RP
Jiang
H
H
Omar
H A
HA
Tejani
N
N
Wolin
M S
MS
D000328:Adult; D001158:Arteries / Q000187:drug effects / Q000502:physiology; D005576:Colforsin / Q000494:pharmacology; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D007773:Lactates / Q000494:pharmacology*; D019344:Lactic Acid; D009126:Muscle Relaxation / Q000187:drug effects* / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology; D005996:Nitroglycerin / Q000494:pharmacology; D010920:Placenta / Q000098:blood supply*; D011225:Pre-Eclampsia / Q000503:physiopathology*; D011247:Pregnancy; D014665:Vasodilator Agents / Q000494:pharmacology; D014680:Veins / Q000187:drug effects / Q000502:physiology
D007773:Lactates; D014665:Vasodilator Agents; D005576:Colforsin; D019344:Lactic Acid; D005996:Nitroglycerin