Effect of bioamines on the cellular differentiation of Hartmannella culbertsoni

Abstract

Epinephrine, 5-hydroxytryptamine, dopamine and tyramine induce axenic encystation of the free living amoeba Hartmannella culbertsoni. Cycloheximide inhibits encystation of amoeba mediated by the amines. The amines uniformly stimulate 3 to 4-fold the ability of the cells to synthesize cyclic 3',5'-adenosine monophosphate from adenosine triphosphate formed in situ. Epinephrine[¹⁴C] is bound to membranes of the amoeba (K_mof binding = 6.5 mM epinephrine). When amoebae are exposed to epinephrine, tyramine, dopamine or cAMP in a non-nutrient medium for 6 hr protein kinase activity is stimulated as evident from increased incorporation of ³²P into cellular proteins.