In this study, the role of cyclic GMP, the end product of the NO-cycli
c GMP signalling pathway, in the regulation of ecNOS was investigated,
Bovine pulmonary endothelial cells were exposed to 8-bromo-cyclic GMP
and its effect on NO production, ecNOS protein, and mRNA levels was a
nalyzed, Endothelial cells on exposure to 8-bromo-cyclic GMP produced
significantly increased amounts of NO, detected as increased cyclic GM
P in cocultures with vascular smooth muscle cells both under basal con
ditions and with agonist stimulation. 8-Bromo-cyclic GMP significantly
increased the ecNOS protein and mRNA levels as detected on Western an
d Northern blots respectively, This 8-bromo-cyclic GMP mediated increa
se of NO production, ecNOS protein and mRNA levels suggests that cycli
c GMP up-regulates the expression of ecNOS, Thus, there may be an inte
rcellular feedback mechanism involved at the molecular level in the ex
pression of the NO-cyclic GMP signalling pathway in blood vessels.