Association between cardiac high-energy phosphate metabolism and whole body metabolism in healthy female adults.

Decline in cardiac high-energy phosphate metabolism [phosphocreatine-to-ATP (PCr/ATP) ratio] and whole body metabolism increase the risk of heart failure and metabolic diseases. The aim of the present study was to assess the relationship between PCr/ATP ratio and measures of body metabolic function. A total of 35 healthy women (56+/-14.0 years of age) underwent cardiac 31P magnetic resonance spectroscopy to assess PCr/ATP ratio - an index of cardiac high-energy phosphate metabolism. Fasting and 2-hour glucose levels were assessed using oral glucose tolerance test. Indirect calorimetry was performed to determine oxygen consumption and resting metabolic rate. There were no significant relationships between PCr/ATP ratio and resting metabolic rate (r=-0.09, p=0.62), oxygen consumption (r=-0.11, p=0.54), fasting glucose levels (r=-0.31, p=0.07), and 2-hour plasma glucose (r=-0.10, p=0.58). Adjusted analysis for covariates including age, body mass index, fat mass, and physical activity, had no significant influence on the relationship between PCr/ATP ratio and body metabolism. In conclusion, the lack of relationship between cardiac PCr/ATP ratio, glucose control and metabolic rate may suggest that overall metabolic function does not influence cardiac high-energy phosphate metabolism.