Influence Of Mitragyna ciliate (Myta) On The Microsomal Activity Of ATPase Na+/K+ Dependent Extract On A Rabbit Heart.

Mitragyna ciliate (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 37oC 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 KM (1.31 mM) but decreased VMAX. This study shows that MYTA exerts a non-competitive inhibition on the microsomal Na+/K+ ATPase extracted from rabbit heart with a Ci50 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. Keywords: Mitragyna ciliate; ATPase Na+/K+; inhibitors of ATPase Na+/K+.African Journal of Trad, Comp and Alternative Medicine Vol. 5 (3) 2008: pp.294-30