Gavi‐Maza, Marisol

The Na + /monocarboxylate transporters (SMCT1 and SMCT2) are expressed several organ between them intestine and kidney, suggesting that its main physiological function are the absorption of fuel molecules involved in cellular metabolism and have only one ‐COOH group in its chemical structure; (lactate, propionate). Drugs with similar chemical properties also are translocated by SMCTs (B3 vitamin, pyrazinoate). However some propionate‐derivative NSAIDs (ibuprofen) reduce the activity of mammalian SMCT1. Using 22 Na + uptake in Xenopus oocytes injected with zebrafish SMCT’s (zSMCT1, zSMCT2) or human SMCT1 cRNA, we evaluated the effect of aspirin and salicylate on the function SMCT’s. Our results indicate a 22 Na + uptake that is aspirin concentration dependent in all SMCT’s. Similar affinity by aspirin was observed between hSMCT1 (K m ~2.4mM) and zSMCT1 (K m ~2.5 mM) in contrast to a lower affinity of zSMCT2 (K m ~5mM). Also the difference of substrate affinity between zSMCT2 and hSMCT1 was evident by salicylate ( hSMCT1 K m ~4mM vs zSMCT1 K m ~30 mM). Interestingly, although zSMCT1 and hSMCT1 shares a similar affinity and transport capacity for several substrates, the salicylate transport by zSMCT1 was not detected and only reduced a small percentage propionate transport induced by zSMCT1 (~10%) in contrast of ibuprofen which drops to 80%. The clear difference of salicylate transporter between SMCT1 could be explained by changes in the structure of proteins because the amino acids sequences are approximately 50% different, so the salicylate could be candidate for studies of structural‐function between SMCT1. Grant Funding Source : CONACYT48709MJ(CP)