The renin-angiotensin system (RAS) plays an important part in homeostasis through angiotensin IPs role as a vasoconstrictor. Defects in the renin angiotensin system can lead to hypertension, heart attack, and stroke (Weir, 1999). Studies have shown an inverse relationship between Vitamin D3 and blood pressure (Li et al., 2002). While studies have been performed on vitamin D\u27s effect on renin expression, little is known about vitamin D\u27s effect on the angiotensin II high-affinity type 1 (ATi) receptor. The hypothesis for this study was that human iliac artery endothelial cells (HIAEC) supplemented with 1,25-dihydroxy vitamin D3 will express less AT] receptor protein expression than the control group. After exposing the cell to 1,25- dihydroxy vitamin D3, RNA was isolated and RT-PCR was completed using AT| primers. Gel electrophoresis allowed for quantification of expression by measuring the density of bands. Two way ANOVA was used to determine significance, and it was determined that the presence of 1,25-dihydroxy vitamin D3 had no significant effect on either AT] or B-actin expression in HIAE cells. The hypothesis can neither be rejected nor accepted however because the control group did not express AT| and therefore it cannot be determined whether ATi expression would have been reduced
