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Abstract Background: Salt is an important component for normal function of cells. However, we consume more than 10 times the salt that is required. This high salt content affects the renin–angiotensin–aldosterone system (RAAS) that regulates blood pressure (BP) and water content of our body. Angiotensinogen is an oligopeptide hormone precursor serving as a substrate for renin in the formation of angiotensin I. Angiotensin I is converted to angiotensin II that causes vasoconstriction and a subsequent increase in BP. We hypothesized that angiotensinogen secretions increases in the kidney and urine with intake of high salt diet. Methods: Dahl salt sensitive (SS) and salt resistant (SR) male rats (8 weeks old) were fed with high salt (HS) and low salt (LS) diet along with or without aldosterone (ALDO); aldosterone antagonist, eplerenone (EPL); and NADPH oxidase inhibitor, apocynin (APC) for 21 days. Urine samples and kidney were collected; total proteins isolated, and quantified using the microassay procedure and analyzed by western blot for angiotensinogen. Results: Angiotensinogen was detected in the kidney samples of Dahl SS rat when fed either low or high salt diet, whereas angiotensinogen was detected in kidney samples of Dahl SR rats when fed with high salt diets. Angiotensinogen was not detected in urine samples. Conclusions: In conclusion, consuming a high salt diet increases Angiotensinogen that lead to an increase in angiotensin II which may cause an increase in BP. Acknowledgements: Vivien Thomas Summer Research Program, Morehouse School of Medicine, Atlanta, GA, USA.
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EFFECTS OF EXCESS SALT DIET ON ANGITENSINOGEN SECRETIONS IN THE KIDNEY OVER TIME
Chieh-Yin Kuo,Vivien Thomas Summer Research
Program; Department of Pharmacology & Toxicology, Morehouse School of Medicine,
Atlanta.
SALT (SODIUM CHLORIDE, NACL) INTAKE
• Add flavor to our food.
• Adults need ~6g (or around about a teaspoon) of salt a day.
• According to the World Health Organization (WHO), the current global average intake of salt is between 9g and 12g per day or more.
KIDNEY An essential organ in the urinary system Serve for homeostatic functions
(the regulation of electrolytes, maintenance of acid–base balance, and regulation of blood pressure via maintaining salt and water balance)
KIDNEY DISEASES
Kidney removes waste products from blood and regulate the water fluid
High salt diet reduce function and removed less water in the kidney. This result in high blood pressure (BP) and kidney disease .
African American are 3-5 times more likely to suffer kidney failure than Caucasian.
African American with diabetes are 10 times more likely to have kidney failure.
ANGIOTENSINOGEN
Oligopeptide hormone precursor serving as a substrate for renin in the formation of angiotensin I
Angiotensinogen produced in liver
Causes vasoconstriction and a subsequent increase in blood pressure.
RENIN- ANGIOTENSINOGEN
Renin, which is primarily released by the kidneys, stimulates the formation of angiotensin in blood and tissues, which in turn stimulates the release of aldosterone from the adrenal cortex.
Dr Bayorh’s lab has previously shown that a HS diet increases Angiotensin II. My job was to see if HS diet increases Ang II by increasing Angiotensinogen.
RENIN- ANGIOTENSINOGEN
Acts on the adrenal cortex to release aldosterone, which in turn acts on the kidneys to increase sodium and fluid retention
Stimulates the release of vasopressin (antidiuretic hormone, ADH) from the posterior pituitary, which increases fluid retention by the kidneys
Stimulates thirst centers within the brain
HYPOTHESIS
We hypothesized that angiotensinogen secretion increases in the kidney and urine with high salt diet.
METHODSDahl salt sensitive (SS) rat and salt resistance (SR) rats (8
weeks old) were divided into following groups and treated as mentioned below for 21 days.
Group 1 : low salt (0.3% NaCl) control Group 2 : high salt (8% NaCl) diet Group 3 : low salt diet + aldosterone (ALDO; 0.2 mg pellet) Group 4 : high diet + aldosterone (ALDO; 0.2 mg pellet) Group 5 : high diet + apocynin (APC, 1.5 mM in the drinking
water) Group 6 : high diet + Eplerenone (EPL)
Apocynin, is a NADPH oxidase inhibitor; blocks the bad effects of angiotensin IIApocynin, is a NADPH oxidase inhibitor; blocks the bad effects of angiotensin II
Eplerenone, is an aldosterone antagonist; blocks the effects of aldosteroneEplerenone, is an aldosterone antagonist; blocks the effects of aldosterone
METHODS
Microassay Procedure was used to analyzed total protein content in the urine sample of rats.
WESTERN BLOT (WB)-TOTAL PROTEIN SEPARATIONUSING SDS-PAGE
WESTERN BLOT (WB)-TRANSFER OF PEPTIDE TO PBDF MEMBRANE
RESULTS
Normal rat :Average systolic pressure = 121 mmHg; Average diastolic pressure = 84 mmHg;Average mean pressure = 103 mmHg; Heart rate = 380 beats per minute
RESULTS
RESULTS-WESTERN BLOT ANALYSIS ON ANGINOTENSINOGEN
Rat Urine Sample
RESULTS-WESTERN BLOT ANALYSIS ON ANGINOTENSINOGEN
Additional analysis required to better understand the results above.
CONCLUSIONS
These findings suggest that consuming high salt diets increase Angiotensinogen that leads to an increase in Angiotensin II which may cause an increase in blood pressure.
Take Home Message Key messages to protect kidney
health• Become a label reader
• Take every day fresh fruits and vegetables as a major part of diet
• Avoid fast foods and processed food
• Drink more water
Future goal
• Increase the number of samples for Increase the number of samples for this study. this study.
• Also, examine Also, examine how high salt diet affects kidney functions.
ACKNOWLEDGEMENT
Dr. Danita Eatman Dr. Mohamed A. Bayorh Mrs. Aisha Rollins-Hairston Ms. Nithya Rajendran Ms Raeonda Williams Mrs. Wanda Harvey Vivien Thomas Summer Research
Program, Morehouse School of Medicine, Atlanta.
RESOURCES http://www.news-medical.net/news/20120521/Salt-intake-why-is-it-
bad-for-you.aspx http://pcwww.liv.ac.uk/~petesmif/petesmif/why%20do%20we
%20need%20kidneys/the%20kidney%20and%20homeostasis.htm http://totalhealthforall.com/physical-health-fitness/salt-the-silent-
killer-also-known-as-white-death/
