BACKGROUND: Karwinskia humboldtiana (Kh) is a
poisonous plant of the rhamnacea
family . To elucidate some of the subcellular effects of Kh
toxicity ,
membrane fluidity and
ATPase activities as hydrolytic and as
proton -pumping activity were assessed in
rat liver submitochondrial particles .
Rats were randomly assigned into control non-treated group and groups that received 1,1.5 and 2 g/Kg
body weight of dry
powder of Kh
fruit , respectively.
Rats were euthanized at day 1 and 7
after treatment .
RESULTS: Rats under Kh
treatment at all
dose levels tested, does not developed any
neurologic symptoms . However, we detected alterations in
membrane fluidity and
ATPase activity. Lower
dose of Kh on day 1
after treatment induced higher
mitochondrial membrane fluidity than
control group . This change was strongly correlated with increased
ATPase activity and
pH gradient driven by
ATP hydrolysis . On the other
hand ,
membrane fluidity was hardly affected on day 7
after treatment with Kh. Surprisingly, the
pH gradient driven by
ATPase activity was significantly higher than controls despite an diminution of the hydrolytic activity of
ATPase .
CONCLUSIONS: The changes in
ATPase activity and
pH gradient driven by
ATPase activity suggest an adaptive condition whereby the fluidity of the
membrane is altered.