Fig. 1.

Experimental protocols. A: in the kinetic study, primed continuous infusions of tracers of arginine, citrulline, and phenylalanine were performed to determine NO and its precursor metabolism and protein breakdown in the fasted state and in response to citrulline sip ingestions. B: in the peripheral vascular function study, reactive hyperemic forearm blood flow responses (RH-FBF) were determined in the fasted state and in response to a bolus ingestion (10 g) of citrulline (CIT) or placebo (equal parts serine, glycine, and alanine).