| Hypertension is a chronic medical condition, and a primary contributor to severe cardiovascular disease. It can increase mortality risk. Studies have found that a low-grade inflammation is involved in the development of hypertension. In addition, men have been found to have a higher risk of hypertension than age-matched women, while women have an increased risk of hypertension after menopause. Female sex hormones are considered to play a protective role in the development and progression of hypertension. Prostanoids are inflammatory mediators, and have important physiological roles on promoting or suppressing inflammation. Studying the combined roles of these two biochemical families in disease development will be helpful to understand the balance between a self-protective effect and inflammatory response in hypertension, and find effective biomarkers to predict the progression of hypertension. In my study, a reversed phase high performance liquid chromatography is used to develop the separation method. A combination of up to nine prostanoids (PGD2, PGE2, 6-keto PGF1alpha, PGF2alpha, 11-dehydro TXB2, 8-iso PGF2alpha, 13,14-dihydro-15-keto PGA2, 13,14-dihydro-15-keto PGE2 and 15-deoxy Delta12,14 PGJ2) and eight female sex hormones (E1, E2, E3, progesterone, 2-OHE1, 4-OHE1, 16alpha-OHE1, and 2-MeOE1) were chosen as analytes. The separation was performed on a Symmetry C18 4.6 x 250 mm column with 5-mum particle size. A UV detector and is selected to determine the levels of analytes in a single 25-minute run. A solid phase extraction procedure was used to pretreat urine samples before injection. Then the validated separation method was applied to urine samples collected from African American patients with hypertension stage 1 before and after a special physical training. The role of physical exercise on hypertension was investigated by studying the level of change in urinary prostanoids and female sex hormones before and after exercise. The level of urinary prostanoids and female sex hormones is usually too low to be detected with HPLC-UV, which encouraged us to develop a more sensitive method to detect the combination in urine. In the study, a LC-ESI-MS technique was chosen to separate and quantify the analytes. An LC-MS method was developed to quantify the above combination of prostanoids and female sex hormones. In the method, negative ionization mode was used to determine prostanoids, while positive ionization mode for female sex hormones. Compared with the HPLC-UV method, LC-MS provides a lower LOD for analytes. In addition, a theoretical model was developed to build a link between the retention behavior of analytes and chemical structure at an isocratic condition with HPLC-UV. The model was called quantitative structure-retention relationship (QSRR). The molecular descriptors were calculated in a semi-empirical AM1 mode. Multiple linear regression analysis was applied to the molecular descriptors to find a QSRR equation to predict the retention times of prostanoids and female sex hormones. The study is helpful to interpret the retention mechanism of prostanoids and female sex hormones on a C18 column. |
