Maternal metabolizable protein restriction during gestation affects the vascular function of maternal and fetal placental arteries in sheep

We hypothesized isocaloric diets low in protein would decrease the sensitivity of caruncular (CAR) and cotyledonary (COT) arteries compared to placental arteries from ewes receiving adequate metabolizable protein (MP) requirements. Pregnant ewes were fed one of three isocaloric dietary treatments that provided 60% (MP60), 80% (MP80), or 100% (MP100) of the MP requirements. Diets were fed from day 100-130 of gestation. In vitro dose response curves to bradykinin (BK), sodium nitroprusside (SNP), potassium chloride (KCl), and phenylephrine (PE) in CAR and COT arteries were performed. As MP decreased, the sensitivity to a low dose of KCl increased (P = 0.05) in the COT arteries. There was an overall treatment effect in the CAR and COT arteries for the BK dose response curve, where CAR arteries of MP80 ewes were more sensitive (P = 0.05) to BK compared with MP60 and MP100 ewes, and COT arteries of MP60 and MP80 ewes were more sensitive (P = 0.01) to BK compared with MP100 ewes. There were no treatment effects (P > 0.09) on the SNP or PE dose response curves in CAR or COT arteries. The mechanism of the BK induced vasodilation needs to be elucidated. Moreover, MP restriction appears to alter placental vascular function, which could help explain the differences in nutrient flux previously reported.(c) 2022 Elsevier Inc. All rights reserved.

Automated summary

This study hypothesized that isocaloric diets low in protein would decrease the sensitivity of caruncular and cotyledonary arteries. The results showed that low protein intake increased the sensitivity of cotyledonary arteries to low doses of potassium chloride, while caruncular arteries of ewes on 80% MP diet were more sensitive to bradykinin compared to ewes on 60% and 100% MP diets.