Role of nitric oxide in the attenuated pressor responses of pregnant or sodium-deplete sheep

Abstract

Reduced pressor responsiveness to angiotensin II (Ang II) during pregnancy and sodium depletion is a well-known but little understood phenomenon: whether the same mechanisms are involved in both situations is unclear. In pregnant humans, altered vascular reactivity to norepinephrine (NE) has also been demonstrated. Nitric oxide (NO) has been implicated in the modulation of blood pressure (BP) and the maintenance of vascular tone and may be involved in these attenuated responses. We examined the role of NO in the pressor responses to (a) Ang II (5, 10, 25, 50 μg/h) and NE (0.32, 0.65, 1.62, 3.24 mg/h) in pregnant and postpartum sheep, and (b) to Ang II (5, 7.5, 10, 25, 50 μg/h) in sodium-repl..