The effects of transient systemic hypotension on renal oxidative status, morphology and plasma nitric oxide levels in pregnant rats

Abstract

Objective. Transient hypotension attacks, frequently experienced during pregnancy, have detrimental effects on maternal and fetal physiology. Despite the strong autoregulatory mechanisms, kidneys are remarkably sensitive to hypoperfusion. Transient hypotension together with high metabolic demand and increased oxygen requirement during pregnancy may disturb the oxidant status and natural course of nitric oxide (NO) metabolism. Therefore, we investigated in this study the effects of systemic hypotension during pregnancy on kidney oxidant status and morphology and plasma NO levels in an experimental hypotension model in rats.

Methods. Twenty-four rats were allocated into four groups as non-pregnant control (NPC), non-pregnant hypotensive (NPH), pregnant control (PC) and pregnant-hypotensive (PH). Blood pressure was monitored only (NPC, PC) or systemic hypotension by blood withdrawal (NPH, PH) was produced for 30 min following catheterisation on the 15th day of pregnancy or at a corresponding time in the control animals. Animals were sacrificed after 48 h of reperfusion. Malonyldialdehyde (MDA) and reduced glutathione (GSH) levels, superoxide dismutase and catalase activities in the kidneys and plasma NO levels were measured. Tissues were evaluated, histologically.

Results. Hypotension and/or pregnancy elevated MDA levels, which was significant in the NPH and PH groups (p < 0.05). GSH levels were lower in all groups compared with the NPC group (p < 0.05). Pregnancy itself increased NO only in the control animals (p < 0.05), not in the hypotensive pregnant rats. Transient hypotension resulted in kidney damage in both hypotension groups, and damage was more prominent in renal cortical regions. The most severe effects were seen in the PH group (p < 0.05).

Conclusions. The findings of this study show that transient hypotension induces a kidney injury in pregnant rats. MDA and GSH in kidneys seem to play a role in the pathophysiology of this injury. However, the roles of antioxidant enzymes and NO and the other underlying mechanisms deserve and necessitate further investigation regarding the long-term health of the mother and fetus.

Keywords:

• Hypotension
• pregnancy
• oxidative stress
• renal injury
• nitric oxide