Exercise increases plasma AICAR (5‐amino‐4‐imidazolecarboxamide riboside) in the horse

Abstract

AICAR (5‐amino‐4‐imidazolecarboxamide riboside) is endogenously produced from an intermediate in the purine biosynthetic pathway. In human athletes, urine [AICAR] correlates with gender (males > females), athletic season (in competition > out of competition), and sport (weight lifting > soccer). Plasma AICAR was hypothesized to increase with exercise. An LC‐MS‐MS method was developed to quantify AICAR in plasma collected from race horses before and immediately after competition. Plasma AICAR was increased in the majority of horses after racing (n = 52, p < 0.0001). [AICAR] did not correlate with age, gender, or performance in this population. When administered intravenously, AICAR (1.0 mg/kg/min; 10 min) acutely (minutes) decreased mean arterial blood pressure (132 to 103 mmHg; n = 1) despite a compensatory increase in cardiac output (36 to 85 L/min; n = 1) and heart rate (41±4 to 72±14 bpm; n = 4). Exercise‐induced increases in AICAR may facilitate vasodilation. This work was supported by the Racing Medication and Testing Consortium, the PA Racing Commissions, the Pennsylvania Harness Horsemen Association, the Meadows Standardbred Owners Association, and the Pennsylvania Horsemen Benevolent and Protective Association.