Ketamine-induced neuromuscular reactivity is associated with aging in female rhesus macaques

Rhesus macaques represent an important species for translational and pre-clinical research studies across a multitude of disease and injury models, including aging. Ketamine anesthesia is used in humans and non-human primates but may be associated with adverse effects, including neuromuscular reactions. The effects of aging on ketamine adverse effects is not well characterized. Urodynamic recordings and electromyography (EMG) studies were performed in aged (>20 years old) and adult (3.9-14.9 years old) female rhesus macaques under an equal and light plane of sedation by constant rate infusion (CRI) of ketamine. A total of 4 of 41 adult subjects (9.7%) showed clinical signs of ketamine-induced abnormal neuromuscular reactivity, whereas a larger portion of 14 of 26 aged subjects showed similar ketamine-induced neuromuscular reactivity (53.8%; P< 0.001). The ketamine CRI rate was 19.8±0.9 mg/kg/h in adults and lower in aged subjects at 16.5±1.4 mg/kg/h (P