Abstract
Plasma membranes from the promastigote and amastigote forms of Leishmania mexicana mexicana were examined for the presence of an adenosine receptor. Specific binding of selected adenosine receptor ligands was tested for modulation of membrane associated adenylate cyclase activity. Time course experiments utilizing amastigote and promastigote membranes demonstrated that total binding of all adenosine receptor ligands equilibrated within 20 min. All incubations of membranes were conducted for 30 min. Specific, nonspecific and total binding of 3H-cyclohexyladenosine (CHA) and 3H-methyl-2-phenylethyl-adenosine (PIA) to promastigote and amastigote membranes over ligand concentrations of 8 to 400 nM were determined. Scatchard plot analysis of the specific binding data indicated single binding sites for both CHA and PIA with Kd values of 75 nM and 200 nM respectively for promastigotes and 55 nM and 175 nM respectively for amastigotes. Membranes were also found to possess adenylate cyclase activity which could be readily inhibited in the presence of increasing concentrations of adenosine, PIA, and CHA (0 to 1 mM). The rate of promastigote replication and transformation to the amastigote form and transformation of the amastigote to the promastigote stage could all be significantly increased in the presence of the adenosine receptor ligands. This receptor mechanism may therefore act to modulate the rate of cell replication and life cycle transformation.
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Hansen, B., Perez-Arbelo, J. & Chiang, P. EVIDENCE FOR A MEMBRANE ADENOSINE RECEPTOR IN LEISHMANIA MEXICANA MEXICANA (WR224): 79. Pediatr Res 19, 757 (1985). https://doi.org/10.1203/00006450-198507000-00099
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DOI: https://doi.org/10.1203/00006450-198507000-00099