Usefulness of Bioelectrical Impedance Analysis in Macaques: Impact of Sedatives and Potential as Pathophysiological and Aging Indicators

Bioelectrical Impedance Analysis (BIA) non-invasively evaluates body composition and cellular health. Despite widespread clinical use in humans, BIA application in non-human primates (NHPs)—crucial biomedical models—remains unexplored. In this study, we evaluated BIA in Japanese and cynomolgus macaques. Phase angle exhibited age-related trends (increasing during growth, declining with aging) highly consistent with human data. Furthermore, BIA successfully reflected pathological conditions, including hyperglycemia, cardiac disease, and bowel disease in both species. Crucially, comparing ketamine sedation with a triple-anesthetic combination (MMK) revealed that no significant effect of anesthetic protocol on BIA parameters was detected under the conditions tested. These findings suggest that BIA measurements are robust across the anesthetic protocols evaluated in this study. This study provides the first foundational BIA baseline for NHPs. BIA is a reliable, robust, and non-invasive surveillance tool for assessing physiological and pathological states, highlighting its immense clinical utility in primate research.