<qa>  What was the primary renal alteration in the ability to excrete sodium?Rostafuroxin was selected during a research program aimed to synthesizing and selecting new antihypertensive compounds able to interfere with abnormalities in Na tubular reabsorption due to humoral andor genetic mechanisms leading to essential or genetic hypertension. Many studies performed on the Milan hypertensive strain of rats MHS, bearing a primary renal alteration in the ability to excrete sodium and increased blood pressure levels, showed a clear capacity of Rostafuroxin to revert these alteration, reducing systemic blood pressure. 