Expression of a channel-like pathway for adenosine transport in Leishmania donovani promastigotes

L. donovani promastigotes (MHOM/ET/67/HA3) transport adenosine by a route that is sensitive to inhibition by a nonspecific channel blocker, propranolol. At the logarithmic and stationary phases of growth, the transport of 1 microM-3H-adenosine was significantly inhibited (40-50%) by 100 microM-propranolol. In contrast, a strain of Leishmania donovani promastigotes clonally selected to grow in defined medium was only slightly (approximately 10%) inhibited at the logarithmic but not at the stationary phase. These results suggest that the differences in expression of adenosine in the parasites previously reported, may be related to uptake by a channel-like pathway in the promastigotes.