Association Between Circulating Lipids and Vascular Function in Young and Postmenopausal Women

Abstract

Aging is the primary risk factor for cardiovascular disease (CVD), which remains the leading cause of death in the United States. The incidence of CVD increases in postmenopausal women (PMW) and is associated with a decline in vascular endothelial function and stiffening of the large elastic arteries, two important indicators of vascular aging; however, the underlying mechanisms are not completely understood. Traditional risk factors for CVD include a well‐established, causal relationship between low density lipoprotein (LDL) and total cholesterol (TC). In addition to these established markers, there has been increased attention to the added risk that elevated plasma triglycerides (TG) may have on CVD risk; however, whether TG contribute to the decline in vascular function with menopause is not known. Accordingly, we sought to examine the relation among common lipid markers and vascular function in young and postmenopausal women. We hypothesized that there would be an inverse relation between plasma TG and vascular function and that this relation would be stronger in PMW compared to young women (YW).METHODSNinety‐two women (53 PMW and 39 YW) completed a fasting blood draw and flow‐mediated dilation (FMD) was measured to assess vascular endothelial function. In a subset of women (29 PMW and 18 YW) large elastic artery stiffness was assessed by carotid‐femoral pulse wave velocity (PWV). All young women were tested during the early follicular phase of the menstrual cycle or the placebo phase of oral contraceptive use, and PMW were a minimum of one year since their last menstrual cycle. Group differences were analyzed using t‐test and associations tested with Pearson correlations.RESULTSPMW were older (59±6 vs.24±6 years; p<0.001), exhibited higher TC (207±31 vs 168±32 mg/dL; p<0.001) LDL (115±29 vs. 88±28 mg/dL; p<0.001) and HDL (76±17 vs. 64±14 mg/dL; p<0.01). BMI (24±4 vs. 23±3 kg/m2; p=0.053) and TG did not differ between the two groups (77±29 vs.77±38 mg/dL; p=0.920). As expected, PMW had lower FMD (4.89±2.54 vs. 7.15±3.25 %; p<0.001), and higher PWV (7.37±1.39 vs.5.63±0.93 m/s; p<0.001) compared to YW. Within each group there was no relation between TC, LDL, HDL or TG with FMD. PWV was inversely associated with HDL (r= −.499; p<0.001) and positively associated with TG (r = .595; p<0.001) in PMW. Interestingly, in YW, there was a positive association between PWV and HDL cholesterol (r = 0.509; p<0.05) whereas the negative association between PWV and TG was not significant (r = −0.448; p=0.06).CONCLUSIONAlthough we did not observe any relation between lipid markers and endothelial function in either age group, our findings suggest that plasma TG levels may contribute to stiffening of the large elastic arteries and that this effect is greater in PMW. Additional data are needed to determine the mechanisms by which increased TG may lead arterial stiffening in women across the menopausal transition and whether TG affect arterial stiffness similarly in men.Support or Funding InformationSupported by NIH R01 HL146558, P20 GM113125