Maternal Na⁺ intake induces renal function injury in rats prevented by a short-term angiotensin converting enzyme inhibitor

The Na⁺ -ATPase, a secondary pump in the proximal tubule, is only weakly responsive to angiotensin II in adult offspring exposed perinatally to high Na⁺ intake. We have investigated whether the offspring from mothers given 0.3 mol/L NaCl show an ineffective angiotensin II action to increase in blood pressure. It was hypothesized that functional alterations at adult life are associated with the number of angiotensin II-positive cells in the developing kidney, with increased oxidative stress in maternal/foetal organs, or with morphometrical changes in placentas. Wistar female rats were maintained on 0.3 mol/L NaCl in their drinking water from 20 days before conception until weaning. After weaning, some of the male offspring were treated with enalapril for 21 days. Glomerular filtration rate was recorded up to 210 days of age, when mean arterial pressure was measured after infusion of angiotensin II. To investigate the placenta and foetal kidneys, mothers on tap water or NaCl were also treated with alpha-tocopherol, pregnancy being interrupted on the 20th day. There were no changes in the number of cells positive for angiotensin II in the foetal kidney and unchanged lipid peroxidation in the placenta of offspring exposed to NaCl, but the intermediate trophoblast area in the junctional zone was increased, possibly reducing maternal-foetal exchange. Glomerular filtration rate was reduced and there was an attenuated effect of angiotensin II on elevation of blood pressure, which could be mediated by an elevated angiotensin II during early life, once these disturbances had been prevented by early and short-term treatment with enalapril.