Mitragyna ciliata
(MYTA) (Rubiaceae) inhibits plasmodia activity. MYTA induces a cardiotonicity of the digitalic type on rat’s isolated heart. In this work we studied the effect of MYTA on microsomal Na
+/K
+ -dependant ATPase (Na
+, K
+ ATPase) extracted from the heart of a rabbit since digitalics inhibit Na
+, K
+ ATPase. Our results revealed that the Na
+/K
+ ATPase has an optimum pH of 7.4 and temperature of 37°C respectively. There is a linear relationship between the organic phosphate formed and the incubation time over 25 mins incubation period. The ATP hydrolysis rate in the presence of MYTA was 0.775 µM/min. LINEWEAVER and BURK plots showed that MYTA did not alter K
M (1.31 mM) but decreased V
MAX. This study shows that MYTA exerts a non-competitive inhibition on the microsomal Na
+/K
+ ATPase extracted from rabbit heart with a Ci
50 of 48 µg / ml. We conclude that the mechanism of action of MYTA is linked to the inhibition of the Na
+/K
+ ATPase like cardiotonics of the digitalic type.