Maternal protein restriction in the rat impairs resistance artery but not conduit artery function in pregnant offspring

Abstract

Dietary protein restriction during gestation has been shown to produce vascular dysfunction in pregnant rats and hypertension in their offspring. However, no studies have to date examined the effects of such 'programming' on the vascular function of female offspring when they in turn become pregnant. We have therefore studied isolated conduit and resistance artery function from pregnant female offspring of control (C, 18 % casein) and protein-restricted (PR, 9 % casein) pregnant dams. There were no differences in birth weight, weight gain during pregnancy, litter size, fetal weight, placental weight, fetal : placental weight ratio or organ weights between the C and PR groups. In isolated mesenteric arteries, the vasodilatation in response to the endothelial-dependent vasodilator acetylcholine (ACh) and the beta-adrenoceptor agonist isoprenaline was decreased in the PR group, while there were no differences in the constriction in response to potassium (125 mM) or the alpha1-adrenoceptor agonist phenylephrine (PE). No differences in any responses were seen in the isolated thoracic aorta. We conclude that dietary protein restriction in pregnancy programmes vasodilator dysfunction in isolated resistance arteries of female offspring when they become pregnant, but does not affect conduit arteries.

Figure 1. Growth of female offspring before mating of C (○) and PR (•) rat dams

** P < 0.01 effect of diet vs. control (two-way ANOVA).

Figure 2. Vasoconstriction induced by phenylephrine (PE) in arteries from pregnant offspring of C (○) and PR (•) pregnant rat dams

A, thoracic aorta (C, n = 5; PR, n = 5). B, small mesenteric arteries (C, n = 8; PR, n = 9).

Figure 3. Vasodilatation induced by acetylcholine (ACh) in PE preconstricted arteries from pregnant offspring of C (○) and PR (•) pregnant rat dams

A, thoracic aorta (C, n = 5; PR, n = 5). B, small mesenteric arteries (C, n = 7; PR, n = 8). ** P < 0.01vs. -log EC₅₀ of control relaxation. Results are expressed as percentage relaxation of tone induced by PE (EC₈₀).

Figure 4. Vasodilatation induced by isoprenaline in PE preconstricted arteries from pregnant offspring of C and PR pregnant rat dams

A, thoracic aorta (○, C, n = 5; •, PR, n = 5). B, small mesenteric arteries (○, C, n = 7; •, PR, n = 8). *** P < 0.0001vs. control maximum relaxation. C, small mesenteric arteries in the presence of l-NAME (□, C, n = 5; ▪, PR, n = 8). Results are expressed as percentage relaxation of tone induced by PE (EC₈₀).