Objective Nitric oxide (NO) production by inducible NO synthase (iNOS) may
play an important role in the pathogenesis of atherosclerosis. Although lov
astatin has been shown to reduce the progression of atherosclerosis, it is
not known whether it regulates NO production. We investigated the effects o
f lovastatin on NO synthesis and the mechanisms by which lovastatin exerts
its effects in rat vascular smooth muscle cells.
Methods Primary cultures of the vascular smooth muscle cells were obtained
from the media of the thoracic aorta of Sprague Dawley rats (200 - 250 g).
Nitrite levels in the culture medium of rat vascular smooth muscle cells we
re determined colorimetrically.
Results Lovastatin (10(-5) mol/L) significantly increased interleukin-1 bet
a (IL-1 beta, 10 ng/mL)-induced nitrite accumulation in a time (0 - 24 hour
s)-dependent manner, Exogenous mevalonate and geranylgeranyl-pyrophosphate
completely reversed the stimulatory effects of lovastatin on nitrite produc
tion. Furthermore, inhibition of Rho by C3 exoenzyme mimicked the increase
in IL-1 beta -induced nitrite accumulation induced by lovastatin in the vas
cular smooth muscle cells.
Conclusion These results demonstrate that lovastatin up-regulates NO format
ion in rat vascular smooth muscle cells stimulated by IL-1 beta, and the ef
fect may be associated with the inhibition of Rho activity.