Microdialysis of neuropeptide Y in human muscle tissue

Microdialysis of neuropeptide Y (NPY) has been reported to be difficult, which partly may be due to the adhesive nature of the molecule. The aim of this study was to determine the optimal probe and perfusion medium for microdialysis of NPY and to investigate if microdialysis can be used to sample NPY from human muscle tissue. Three different probe types with a 10mm membrane were used for experiments in vitro. They were perfused with a modified Krebs-Henseleit buffer (KHB), with or without the addition of 0.5% human serum albumin (HSA). Dialysate samples were collected at different flow rates. Ten healthy subjects participated in the clinical microdialysis. Microdialysis samples were obtained by probes inserted intramuscularly in the right masseter and trapezius muscle and perfused with KHB+HSA at a flow-rate of 4 microl/min. The relative recovery of NPY was significantly higher in the dialysates with HSA added to the perfusion medium, while there was no difference between the three probe types. NPY was detectable in 90% of the dialysates from the masseter and in 40% of the dialysates from the trapezius muscle. In conclusion, this study shows that NPY can be detected in microdialysis samples from human skeletal muscle and that addition of HSA to the perfusion medium increases the relative recovery in vitro.