Novel Variants of Angiotensin Converting Enzyme-2 of Shorter Molecular Size to Target the Kidney Renin Angiotensin System

Wysocki, Jan; Schulze, Arndt; Batlle, Daniel

2.6. Recovery of Urinary ACE2 after Recombinant ACE2 Infusion to ACE2-Deficient mice and the Effect of Blocking Tubular Reabsorption with L-lysine Immediately after the ACE2-deficient mice [26, 27] voided urine (baseline urine collection), purified mouse recombinant ACE2 proteins were administered as a single i.v. bolus injection at a dose of 1.0 µg/g body weight. In order to determine the impact of ACE2 protein reabsorption in the proximal tubule, lysine, a blocker of proximal tubular reabsorption [28, 29] was also administered (0.4 mg/g body weight) as a single i.p. injection. The timeline of the experiment was as follows: mice were weighted, followed by collection of baseline urine levels, and, within 5-10 min after voiding urine, mice were administered mrACE2 proteins in a single i.v. injection (0.2 mL/mouse, 1 µg/g BW). Then, immediately after i.v. injection, to collect urine, mice were placed for 2 h in urine collection cages with access to water and food. Afterwards, L-lysine was injected i.p. Urine was collected again within 2 h after the subsequent i.p. injection of the tubular reabsorption blocker, L-lysine (0.4 mg/g body weight).