Increased myogenic responses of resistance-sized mesenteric arteries after reduced uterine perfusion pressure in pregnant rats.

Objective: A central component of preeclampsia is a reduction in utero-placental perfusion. We tested the hypothesis that vascular reactivity of second - order mesenteric arteries would be increased in a pregnant rat with reduced uterine perfusion pressure (RUPP).

Methods: Pregnant 10-12 week old Sprague-Dawley rats underwent RUPP surgery on gestational day 14, and experiments were carried out on day 20.

Moderate ascorbate deficiency increases myogenic tone of arteries from pregnant but not virgin ascorbate-dependent rats.

Plasma ascorbic acid is decreased in women with the pregnancy disorder preeclampsia. We used a mutant strain of rats (Osteogenic Disorder Shionogi), dependent on dietary sources of vitamin C, to investigate whether reduced intake of the vitamin would differentially affect vascular function in late-pregnant (day 19) and age-matched virgin rats. The animals were given either 1 mg/mL of ascorbic acid ad libitum in drinking water [fully supplemented (FS)] or 0.

Myogenic reactivity is reduced in small renal arteries isolated from relaxin-treated rats.

Administration of the ovarian hormone relaxin to nonpregnant rats vasodilates the renal circulation comparable to pregnancy. This vasodilation is mediated by endothelin (ET), the ET(B) receptor, and nitric oxide. Furthermore, endogenous relaxin mediates the renal vasodilation and hyperfiltration that occur during gestation.