Developmental aspects of the renal responses to hemorrhage during converting-enzyme inhibition in fetal lambs

R A Gomez, J E Robillard
1984 Circulation Research  
The role of the renin-angiotensin system in modulating the renal hemodynamic and functional responses to reductions of fetoplacental blood volume (8.8-35.5%) was studied in two groups of fetal lambs (<120 days and >130 days gestation; term 145 days) during infusion of either captopril (experimental fetuses) or dextrose 5% in water (control fetuses). At high hemorrhage levels (level III), renal blood flow decreased and renal vascular resistance increased significantly in both groups of fetuses
more » ... groups of fetuses (<120 days and >130 days), either treated or not treated with captopril. However, at low hemorrhage levels (levels I and II), and contrary to what was observed in young fetuses (<120 days), near-term fetuses (>130 days) receiving captopril showed neither significant decreases in renal blood flow nor increases in renal vascular resistance, whereas untreated fetuses of the same gestational ages demonstrated significant decreases in renal blood flow and increases in renal vascular resistance. It was found in both <120 day and >130 day fetuses that hemorrhage is associated with a decrease in urinary flow rate and free water clearance accompanied by an increase in urine osmolality and sodium reabsorption. It was shown that captopril does not modify this response. The present study also demonstrated that the blood pressure response to hemorrhage was characterized by a similar decrease in <120 day fetuses, whether treated or untreated with captopril. On the other hand, blood pressure did not change in control fetuses >130 days, but decreased slightly in captopril-treated fetuses during hemorrhage. Taken together, the present results tend to suggest that the renin-angiotensin system may be an important modulator of the renal hemodynamic response to low level hemorrhage as fetuses approach term, and may be more important in controlling blood pressure in near-term than in young fetuses. (Circ Res 54: 301-312, 1984)
doi:10.1161/01.res.54.3.301 pmid:6321056 fatcat:h4g3cpi6hvdfdi72xolbe6rbue