Discipline: Biological Sciences
Subcategory: Cell and Molecular Biology
Jamie Binns - Talladega College
Co-Author(s): James J. Galligan and Hui Xu, Michigan State University, East Lansing, MI
Hypertension is a commonly diagnosed cardiovascular disorder affecting Americans. Studies have shown links between obesity and hypertension. Obesity associated hypertension in rodent models is commonly associated with increased sympathetic activity and altered vascular reactivity to sympathetic neurotransmitters. As higher vascular reactivity to sympathetic neurotransmitters causes arterial constriction, increases vascular peripheral resistance, and blood pressure, I hypothesized that obesity may increase the arterial responses to sympathetic neurotransmitters (norepinephrine, NE; and ATP), which could also contribute to obesity associated hypertension. Male Sprague-Dawley rats were placed on high fat diet (HFD, 60% kcal n=5) or normal-fat diet (NFD; 10% kcal from fat n=5) for 20-22 weeks after weaning (3 weeks of age). Compared with NFD rats, HFD rats were obese (836±39g vs 617±144g, P<0.05), but not hypertensive (MAP, 108±1 mmHg vs 107±6 mmHg, P>0.05, measured by radiotelemeter). NE and ATP-induced arterial constrictions were determined in cannulated and pressurized small mesenteric arterial (~300 m inner diameter, 60 mmHg) from HFD and NFD rats in vitro. Vessels were constantly perfused with oxygenized (21% O2) and heated (36ºC) Kreb’s buffer. Drug-induced percentage changes in arterial inner diameter were recorded using Diametrack software. Concentration response curves for NE and ATP were plotted and the EC50 values of each drug (the concentration of a drug that gives half-maximal response) were calculated using Origin software. NE-induced maximal constriction and pD2 (EC50) were 89.±22% and 6.2±0.35 (n=4) in NFD rats; 94.% and 6.8 (n=1) in HFD rat. ATP-induced maximal constriction and pD2 (EC50) were 44.% and 1.2 (n=1) in NFD rats; 72.% and 3.8 (n=1) in HFD rat. My studies indicated that obesity may not be necessarily correlated with hypertension in rats. The conclusions of altered arterial reactivity to neurotransmitter cannot be made from my current studies, due to the lower animal numbers in HFD rats.
Funder Acknowledgement(s): NIH R25HL103156; NIH2P01HL070687-11A1
Faculty Advisor: Hui Xu, firstname.lastname@example.org
Role: I enjoyed the opportunity to work in such a prestigious laboratory at Michigan State University, Dr. James Galligan's Blood Vessel Lab. As a student attending a small college, resources are limited. It was rewarding to practice some of the concepts that I had been theoretically taught. Being able to practice and learn the needed skills and techniques provided me greater insight into my specific research.