[Effect of temperature on plasma concentration of FK506].
Because the affinity of FK506 for red blood cells is strong, plasma FK506 levels vary depending upon the temperature at which plasma is separated from whole blood. This study was undertaken to investigate the effects on plasma FK506 of blood temperature at the time of separation and of its rewarming at 37 degrees C, using A) blood samples from rats administered with FK506 at 1 mg/kg for 7 days, and B) human blood samples added with FK506 at 1.0, 3.2 and 10 ng/ml in vitro. 1) Plasma FK506 levels of samples from rats were not affected by storage time, but samples separated at 20 degrees C were significantly lower in FK506 levels than those separated at 37 degrees C. Plasma FK506 level after rewarming blood at 37 degrees C was not significantly different from that of blood stored at 37 degrees C. 2) FK506 levels in human plasma, separated at 30 degrees C and 20 degrees C were 51% and 33%, respectively, of the corresponding value for plasma separated at 37 degrees C. But the level of plasma separated at 0 degrees C was 56%, which was higher than that at 20 degrees C. 3) Rewarming of human blood at 37 degrees C for 5 minutes allowed the plasma FK506 level to return to the initial level. FK506 levels of plasma separated without regard to temperature are less reliable and reproducible.(ABSTRACT TRUNCATED AT 250 WORDS)
Machida
M
M
Department of Urology, Gunma University School of Medicine.
D000818:Animals; D001793:Blood Preservation; D006801:Humans; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D016559:Tacrolimus / Q000097:blood*; D013696:Temperature
D016559:Tacrolimus