Genetic Mechanisms in Human Hypertension

Thank you for your interest in the investigators Genetics and Blood Pressure Research Study.
The National Institutes of Health are sponsoring us to investigate why patients develop high
blood pressure, atherosclerosis (hardening of the arteries), and heart disease. There are two
parts of the investigators research program. The first part is a screening visit. At this
visit you will be given a brief physical exam and will be asked questions concerning your
medical history. During the same visit you will have your blood drawn for routine screening
and to prepare DNA for genetic testing. You will also be asked to collect a urine sample for
routine screening.

If the doctor finds that you are a healthy candidate you will be invited to participate in
the second part of the study. During Phase II, the investigators will perform physiological
tests after you are placed on a low salt diet and again after you are placed on a high salt
diet. If you are on blood pressure medication, it may be necessary to discontinue taking your
present medication for up to three months before beginning the study. Patients discontinuing
their current blood pressure medication may be placed on a different blood pressure
medication during this washout period if necessary to maintain blood pressure at pre-study
levels. The investigators will take you off all medications at about two weeks prior to your
scheduled in-patient study (overnight visits).

Once your blood pressure medications are discontinued, you will be closely monitored to make
sure you do not encounter any difficulty. If you do not own a home blood pressure monitor,
the investigators will provide one for you to use during the study so that you can keep a
daily record of your blood pressure readings. The investigators will ask you to call us every
three days to report your blood pressure readings. Less than 20% of patients have any
significant increase in their blood pressure during this short time off of therapy. After you
have stopped taking your medication, dieticians at the hospital will make you low salt meals
to eat at home for seven days. On the seventh day of the low salt diet, you will be asked to
begin a 24-hour urine collection that you will bring with you when you are admitted to the
hospital that evening. That morning, you will be required to come to the Clinical Research
Center for a one-hour test to check if your body is in the correct salt balance. You will
return that evening to the inpatient Clinical Research Center where you will be admitted for
your study that will occur the next morning. On the morning of your low salt study, you will
have naturally occurring hormones administered and blood samples drawn from an intravenous
needle. The investigators will also take ultrasound pictures of your heart to see how salt
and hormones affect the way the heart functions. These tests will last approximately five
hours and you will be discharged around 2:00 PM. For the next five days, you will be placed
on a high salt diet. During these five days, you will eat all your own food, but the
investigators will give you some supplements to eat with your meals. After five days on your
high salt diet, on the morning of your second admission to the hospital, you will be asked to
begin a final 24-hour urine collection. That morning, you will again be required to come to
the Clinical Research Center for a one-hour test to check if your body is in the correct salt
balance. You will return that evening to the inpatient Clinical Research Center where you
will be admitted for your final study that will occur the next morning. The same study that
was done for the low salt study will be repeated for the high salt study. You will be
discharged around 2:00 p.m. This study will determine if you are salt-sensitive. In addition,
the investigators hope to learn more about the hormones that regulate your blood pressure and
the genes responsible for regulating those hormones.

You will be placed back on your initial blood pressure medication (if you are on any) and
returned to your regular physician for care. The investigators will provide clinically
relevant information to you and your physician.