mRNA expression of nitric oxide synthase and no production in human monocytes in essential hypertension.

to evaluate inducible (i-NOS) and constitutive (c-NOS) NO synthase mRNA expression and NO production, in human peripheral blood monocytes (PBM) and umbilical vein endothelial cells (HUVEC), in basal condition and after vasoactive stimuli. PBM were purified from healthy donors and hypertensive (HT) subjects; HUVEC and PBM were incubated 4 hours at 37°C in basal condition and after addition of physiologic concentration of Epinephrine, Dopamine, Endothelin-1 (ET-1), Angiotensin II (AII), Cortisol and Bradykinin (BK). After total m-RNA extraction RT-PCR was performed resulting in amplification of i-NOS and c-NOS mRNA fragments. Due to the High affinity binding between NO and Fe-eme, Electronic Paramagnetic Resonance Spectroscopy (EPR), that detects the complex NO-Hb, was used to evaluate NO production. c-NOS mRNA was detectable in basal condition in HUVEC and PBM and was not significantly influenced by vasoactive hormones. In contrast, i-NOS mRNA, unconstantly detectable in basal condition, increased after Epinephrine, Dopamine, ET-1 and AII stimulation, in normotensive PBM and HUVEC, while Cortisol and BK did non affect the basal expression. EPR experiments confirmed these findings. In HT i-NOS mRNA and NO were mostly detectable in basal condition. In conclusion i-NOS mRNA and NO in PBM and HUVEC may be induced by vasoconstrictive hormones, such as Epinephrine, AII and ET-1, beside LPS and γIFN. Moreover i-NOS expression may be higher in basal condition in HT. these data suggest a possible role in the regulation of vascular tone for this enzyme. Finally c-NOS and i-NOS mRNA expression show the same pattern of behaviour, after stimuli, in HUVEC and PBM, so that PBM may provide a interesting experimental model in NOS isoform evaluation in HT.