Key result
Cultured rat mesenteric endothelial cells do not express endothelial NOS but respond to inflammatory cytokines by expressing iNOS, a process blocked by tyrosine kinase inhibition.
Rat mesenteric endothelial cells lack basal eNOS expression but can be induced to express iNOS by inflammatory cytokines via a tyrosine kinase-dependent pathway.
Leaves open tyrosine kinase targeting of cytokine-induced iNOS in mesenteric endothelium; hypothesis-generating without human or in vivo validation.
Most of the available data on the nitric oxide (NO) pathway in the vasculature is derived from studies performed with cells isolated from conduit arteries. We investigated the expression and regulation of components of the NO synthase (NOS)-NO-cGMP pathway in endothelial cells from the mesenteric vascular bed. Basally, or in response to bradykinin, cultured mesenteric endothelial cells (MEC) do not release NO and do not express endothelial NOS protein. MEC treated with cytokines, but not untreated cells, express inducible NOS (iNOS) mRNA and protein, increase nitrite release, and stimulate cGMP accumulation in reporter smooth muscle cells. Pretreatment of MEC with genistein abolished the cytokine-induced iNOS expression. On the other hand, exposure of MEC to the microtubule depolymerizing agent colchicine did not affect the cytokine-induced increase in nitrite formation and iNOS protein expression, whereas it inhibited the induction of iNOS in smooth muscle cells. Collectively, our findings demonstrate that MEC do not express endothelial NOS but respond to inflammatory stimuli by expressing iNOS, a process that is blocked by tyrosine kinase inhibition but not by microtubule depolymerization.
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Papapetropoulos et al. (2001) studied this question. Cytokines, genistein, and colchicine vs. Untreated cells was evaluated on Expression of iNOS mRNA and protein, nitrite release, and cGMP accumulation. Cultured rat mesenteric endothelial cells do not express endothelial NOS but respond to inflammatory cytokines by expressing iNOS, a process blocked by tyrosine kinase inhibition.
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