Characterization of the myocardial and renal renin-angiotensin system in normal cats and cats with hypertrophic cardiomyopathy.

Feline myocardial and renal RAS enzyme activity is quantifiable but unstable during postmortem sampling.

This study characterized the tissue renin-angiotensin system (RAS) in feline myocardial and renal tissues for the first time. Researchers analyzed RAS enzyme activity and angiotensin peptide concentrations in necropsy samples from 17 adult cats: 8 with echocardiographically normal hearts and 9 with hypertrophic cardiomyopathy (6 stage B1, 3 stage C). Tissues were incubated with angiotensin I or II under various conditions to assess enzyme contributions to angiotensin II and angiotensin 1-7 formation. Key findings demonstrated that RAS enzyme activity was present and quantifiable in both myocardial and renal tissues. Angiotensin-converting enzyme (ACE) contributed over 85% to angiotensin II formation across all tissues. However, angiotensin peptide concentrations did not significantly differ between normal cats and those with HCM. The study identified a critical methodological limitation: RAS enzyme activity and peptide concentrations changed during the postmortem period (3-hour delay), suggesting that necropsy-based RAS studies require careful timing considerations. These findings establish baseline RAS characterization in feline tissues and provide important technical insights for future feline cardiovascular research.

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