Abstract
Sarcolemmal vesicles prepared from rat heart exhibited ATP-dependent uptake of S-(2,4-dinitrophenyl)glutathione (DNP-SG), which obeyed Michaelis-Menten kinetics with an apparent K m of 21 μM for DNP-SG and a V max of 0.27 nmol · 10 min−1 · mg protein−1. Several model glutathione S-conjugates inhibited DNP-SG uptake, but leukotriene C4 inhibited uptake much more significantly even at lower concentrations (competitive inhibition, K i = 1.5 μM). However, leukotrienes D4 and E4, which lack the γ-glutamyl moiety, were less effective. The results suggest that the ATP-dependent transport system has a high affinity for leukotriene C4, and may be responsible for the translocation of this compound.