CONCLUSIONS: Under control diet conditions, TMP inhibited ENaC function, without changing urinary H^(+) excretion. This finding further supports the hypothesis that the inhibition of ENaC per se does not impair H^(+) excretion in the collecting duct. Moreover, TMP-induced urinary alkalization in animals fed a low K^(+) diet highlights the importance of renal H^(+)/K^(+)-ATPase-mediated H^(+) secretion in states of K^(+) …