Vascular reactivity in normal and abnormal gestation.
Preeclampsia is characterized by enhanced pressor responsiveness to angiotensin II. This report summarizes studies by our laboratory to investigate possible roles for calcium, sodium, membrane pumps, and the vasoactive hormones, atrial natriuretic peptide (hANP) and endothelin, in modulating the change in vascular reactivity characteristic of preeclampsia. Urinary calcium excretion, 1 alpha-25(OH)2D3 levels, and serum free calcium levels were all decreased, whereas parathyroid hormone levels and intraplatelet calcium concentrations were increased in women with preeclampsia. Erythrocyte sodium content was elevated, while red blood cell membrane Na-K-ATPase activity was decreased in patients with severe disease. Preeclamptics also had elevated levels of hANP, which failed to increase further when saline was infused or when blood pressure was increased transiently with angiotensin II administration. Finally, endothelin levels that are reduced in normal gestation, were increased in preeclampsia. While the cause of increased vascular reactivity is still unclear, there appear to be changes in the intracellular cation environment, combined with loss of compensating mechanisms, both at the membrane and humoral level, as well as enhanced concentrations of a potent vasoconstrictor in blood; all which lead to increases in vasoreactivity and blood pressure in preeclampsia.
Mochizuki
M
M
Department of Obstetrics and Gynecology, Kobe University School of Medicine, Japan.
Morikawa
H
H
Yamasaki
M
M
Maruo
T
T
D009320:Atrial Natriuretic Factor / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D002118:Calcium / Q000502:physiology; D016232:Endothelins / Q000502:physiology; D005260:Female; D006801:Humans; D011225:Pre-Eclampsia / Q000378:metabolism / Q000503:physiopathology*; D011247:Pregnancy; D012964:Sodium / Q000502:physiology; D014661:Vasoconstriction / Q000502:physiology
D016232:Endothelins; D009320:Atrial Natriuretic Factor; D012964:Sodium; D002118:Calcium