Brain and nerve cells communicate with each other by releasing and picking up chemicals
called neurotransmitters. Norepinephrine is a neurotransmitter used by part of the nervous
system activated during stress called the sympathetic nervous system. The sympathetic
nervous system is involved with regulating blood pressure and pulse rate. Researchers
believe the level norepinephrine in the blood can be used to measure activity of the
sympathetic nervous system.
This study is designed to answer important questions about rates of release of
norepinephrine into the blood stream, removal of released norepinephrine, and the
sympathetic nervous system response to stress.
Researchers will attempt to measure levels of norepinephrine and activity of the sympathetic
nervous system in patients with high blood pressure, normal patients with family histories
of high blood pressure, patients taking drugs that can effect levels of norepinephrine, and
patients with diseases or conditions directly affecting the sympathetic nervous system.
In order to examine sympathetic nervous system function in neurocardiological disorders and
catecholaminergic effects of dietary manipulations or neuropsychiatric drugs, the protocol
calls for evaluations of the kinetics of 3H-norepinephrine or 3H-epinephrine in patients
with hypertension, dysautonomias, or disorders thought to involve abnormal catecholaminergic
function, and in normotensive normal volunteers. Apparent spillover and clearance rates are
estimated based on the norepinephrine or epinephrine concentration during the infusion and
their steady-state specific activities, under resting conditions and in response to
physiological or pharmacological manipulations thought to affect sympathetic outflows.
Must be greater than or equal to 18 years of age.
Must not be pregnant or lactating.