PET imaging has been recently introduced for investigating the type 1 angiotensin II receptor (AT1R) in vivo. The goal of the present study was to investigate the effects of acute and chronic exposure to angiotensin converting enzyme inhibitors (ACEI) on the AT1R in the dog kidney.Methods
Animals were imaged at baseline, after acute intravenous ACEI treatment and after a chronic 2-week exposure to an oral ACEI. Control animals were imaged at identical time points in the absence of ACEI treatment.Results
In vivo AT1R binding expressed by Ki was increased in the renal cortex by chronic ACEI treatment (p < 0.05). In vitro measurements of AT1R density (Bmax) also revealed significant increases in AT1R in isolated glomeruli (p < 0.05). Plasma renin activity was increased, but angiotensin II (Ang II) and the Ang II/Ang I ratio showed a weak correlation with chronic ACEI treatment, consistent with an Ang II escape phenomenon.Conclusion
This study reveals, for the first time, that chronic ACEI treatment increases AT1R binding in vivo in the dog renal cortex.