Muscle protein fractional synthesis rate formula

[Function]

Hello everyone

 

In order to write a paper, I need to understand the "precursor-product model" formula in order to calculate the FSR of mixed muscle protein.

 

In articles using marked phenylalanine as a tracer, this is the given formula

 

[math]FSR=\frac{\Delta E_p}{t} / \left[\frac{E_{M1}+E_{M2}}{2}\right]\cdot 60\cdot 100[/math]

 

Where Delta(Ep) would be the increment in protein bound tracer, and EM1 and EM2 being "the phenylalanine enrichments in the free intracellular pool in the 2 sequential biopsies" and t being the time.

 

I've got 2 questions:

• Can someone clearly explain to me EM1 and EM2, and why one should divide Delta(Ep) by the mean of EM1 and EM2?
• Why does one multiply by 60?

In articles using marked leucine as a tracer, this is the given formula

 

[math]FSR=\frac{\Delta L_m}{L_p}\cdot\frac{1}{t}\cdot 100[/math]

 

Delta(Lm) is similar to Delta(Ep) and Lp would be "the mean value over time of venous alpha-KIC labelling" and t again the time.

 

Can someone, in accordance to my questions above, explain to me Lp and why one divides by this Lp? And why no factor similar to 60 here?

 

Thanks!

 

Function

Edited February 13, 2016 by Function