Comparison of angiotensin metabolism by brain membranes from SHR and WKY rats

The ability of membrane-associated peptidases from the brains of spontaneously hypertensive rats (SHRs) and normotensive Wistar-Kyoto (WKY) rats to metabolize iodinated angiotensin (125I-Ang II) and 125I-Ang III was compared. 125I-Ang II was metabolized to 125I-Ang III and other fragments exclusively by membrane-associated peptidases. In contrast to 125I-Ang III which was effectively degraded by both membrane-associated and residual cytosolic peptidases, 125I-Ang II was unaltered by contaminating cytosolic enzymes. The ability of SHR-derived membranes to metabolize 125I-Ang II and produce 125I-Ang III was enhanced when compared to membranes from WKY rats. No difference was observed in the ability of membrane or cytosolic enzymes from SHR and WKY rats to degrade 125I-Ang III. These data are consistent with an increased availability of Ang III in the brains of SHRs.