Plasma and tissue angiotensin-converting enzyme 2 activity and plasma equilibrium concentrations of angiotensin peptides in dogs with heart disease

Larouche-Lebel, Éva; Loughran, Kerry A.; Oyama, Mark A.; Solter, Phil F.; Laughlin, Danielle S.; Sánchez, Melissa D.; Assenmacher, Charles-Antoine; Fox, Philip R.; Fries, Ryan C.

Linearity of the MCA standard over the range of concentrations was assessed by linear regression, using reagents prepared as described above (Supplemental Figure 2) . Linearity of the ACE2 assay with varying concentrations of canine ACE2 activity was tested using two canine kidney tissue supernatant fluids. The total protein in each sample was determined by the BCA method. The RFU vs. time curves decreased in both samples when the amount of protein used was reduced. In each of the samples the higher protein concentrations exhausted the ACE2 MCA-synthetic peptide substrate before the end of the 120-minute time period, which was evident as a change in the slope of the curve by the end of the incubation period (Supplemental Figure 3 ).