EARLY DIAGNOSIS OF THE CARDIOVASCULAR SYSTEM - THE NANOMEDICAL EVALUATION OF ENDOTHELIAL DYSFUNCTION
Tadeusz Malinski, M.D., Rudek Ohio University, Athens, Ohio, USA
Background: Endothelial dysfunction can be directly related to the dysfunction of the cardiovascular system. The dysfunctional endothelium is characterized, among others, by the deficiency of bioavailable nitric oxide (NO) and excess production of cytotoxic superoxide (O2-) and peroxynitrite (ONOO-) – the main components of oxidative stress. The studies presented here focus on the early assessment of endothelial dysfunction and its risk associated with the development of cardiovascular diseases.
Methods & Results: We used a nanomedical approach (nanosensors with a diameter of 150-250 nm) to simultaneously measure the production of NO, O2-, and ONOO- in single HUVECs, of different ethnicities (Caucasian, African American, Native American) and different gene variants of endothelial nitric oxide synthase (eNOS). We introduced the parameter R, where R = [NO]/ [O2-] +[ONOO-], to measure the degree of endothelial dysfunction and the K as the rate of NO, ONOO- and O2- production in nmol/s. R varied from about 3.5±0.4 to 1.8±0.3, indicating a significant change in the function of eNOS variants. Dependent upon the eNOS gene variants and ethnicity, the rate K, of NO production also varied from 180±25 nmol/s to 60±15 nmol/s. In a set of separate experiments, [NO]/[O2-]+[ONOO-] balance/imbalance and the kinetics of NO, O2- and ONOO production were also elucidated in the presence of environmental factors like elevated glucose and/or elevated NaCl. Apparently, these environmental factors further increased endothelial dysfunction, unfavorably shifting the [NO]/[O2-] + [ONOO-] balance. This effect was additive to the effect of the gene variants.
Conclusion: The [NO]/ [O2-] +[ONOO-]ratio, as well as the rate of NO, ONOO- and O2- generation, accurately reflects the functional state of the endothelium. This model can be used to design a method for early diagnosis of cardiovascular diseases based on the analysis of a single endothelial cell.