|| Plant essential
oils often are applied to the skin, added to bath water or inhaled, accounting
for some absorption of these components into the bloodstream. Because
there have been many claims as to the relaxing properties of some of these
oils, the effects of nine essential oils on smooth and skeletal muscle
were studied in vitro. Angelica, dill, fennel, frankincense and
nutmeg produced spasmogenic effects on smooth muscle. In the case of clary
sage, this effect was followed by a reduction in field-stimulated contractions.
Thyme and lavender had only a spasmolytic effect on smooth muscle, and
camphor produced an increase
in twitch size for smooth and skeletal muscle. Four different effects
on skeletal muscle were observed overall, wheras only contracture was
observed in smooth muscle. Researchers concluded that essential oils have
selective actions on biological tissues and that their bioactivity is
not due to non-specific toxic actions on cell membranes.