PL 41. The impact of glycosylated serum protein on endothelial dysfunction and vascular erectile dysfunction
Erectile dysfunction(ED) is a common disease in males, and vascular disorder is the most common cause. ED is considered to be the earliest clinical manifestation of cardiovascular diseases (CVD), so ED can be seen as an early warning factor of cardiovascular events. Endothelial dysfunction is the initial triggering factor and most important in the pathogenesis of ED and CVD. Glycometabolism markers significantly correlate with ED. Glucose can be slowly combined with serum proteins and then transformed into glycosylated products, which is the process of non-enzymatic glycosylation reaction. Once glycometabolism is disordered, high level glycated products will increase significantly and impair systemic microvascular tissue. In diabetic patients, abnormally high-levels of advanced glycation end products (AGEs) cause the cardiovascular complications. Glycosylated serum protein (GSP) is an early glycated product which may appear before the occurrence of diabetes. Thus, serum levels of GSP may significantly increase when a potential glycometabolic disorder occurs. Some studies have demonstrated that GSP may damage the biological function of endothelial cells, which may accelerate the development of cardiovascular disease.
To studied the impaired role of glycated serum albumin on vascular endothelium-dependent relaxation in vitro. In clinical study, young ED patients without obvious causes for ED were selected to evaluate the state of glycometabolism and endothelial function and investigate the influence of glycosylated serum protein on vascular erectile dysfunction.
Male SD rats were selected and killed with dislocation. Aorta was cut into vascular rings with a length of 3-4 mm in each. The vascular rings were fixed with steel hook in different constant perfusion tanks, respectively. The vascular rings were divided into three groups including control, BSA and GBSA group. Two tanks were selected to add BSA and GBSA to incubate vascular rings for 60min, respectively. Phe and ACh were used to stimulate the pre-contraction and relaxation of vascular rings, and then a maximum contraction value (Emax0) and diastolic value (Emax1) were marked, respectively.
ED patients aged 20-40 years were screened, and control group which is age-matched with case group were screened from health population. All the participants need to accept systemic data collection. We made the uniform standards for screening and inclusion including IIEF-5 <21 without obvious causes for ED in ED group, and IIEF-5 ≥22 without risk factors of ED in control group. Ultimately, the participants met the screening and inclusion criteria were enrolled in the research cohort. The target patients were then divided into groups for analysis according to the severity of erectile dysfunction determined by IIEF-5 scores.
In vitro, GBSA significantly impaired endothelium-dependent vasodilation. Before treatment, no significant differences were found in maximum expansion rate among three groups of vascular rings. After treatment, the maximum expansion rate of control and BSA groups had no significant difference compared with before treatment. The maximum expansion rate of the GBSA group was significantly lower than before treatment (10.7 ± 8.0 vs. 58.5 ± 0.08, P<0.05), control group (10.7±8.0 vs. 49.1±21.6, P<0.05), and BSA group (10.7±8.0 vs. 45.8±19.2, P<0.05), respectively.
Compared with control group, case group had significantly lower IIEF-5 score. Clinical parameters in two groups showed no significant difference. FBG level of case group was higher than of control group, and GSP level in case group was significantly higher than in control group. In ED group, FMD was significantly lower than that in control group. FMD values decreased and GSP values increased with the increasing severity of ED. FMD value was positively correlated with IIEF-5 score, and GSP level was negtively correlated with IIEF-5 score. There was a significantly negative correlation between GSP and FMD. Multiple linear regression analysis showed FMD and GSP can be used as independent predictors of ED.
Glycosylated serum albumin can impair endotheliumdependent dilation of rat aorta in vitro. Potential endothelial dysfunction and glycometabolism disorder may present in young ED patients without obvious causes. Glycosylated serum protein significantly correlates with endothelial dysfunction and erectile dysfunction, and it may be an early predictor of endothelial dysfunction and erectile dysfunction.
