• Harshfield, Gregory A (PI)

Project: Research project

Project Details


The goals and specific aims of the project remain the same as in
the original application except for changes suggested by the study
section (deletion of the measurement of forearm blood flow and
catecholamines as well as the drug studies in years 4 & 5). The
long term goal of the principal investigator is to determine the
role of genetic and environmental factors in hypertension in
blacks. This research will use the power of the study of twins to
investigate the effect of behaviorally-induced arousal of the
sympathetic nervous system (SNS) on the renal handling of sodium
(Na+) and the hemodynamic and humoral factors mediating
changes in Na+ excretion (ENa+). The specific aims are to answer
the following questions in man: 1.) Does behavioral induced
arousal of the SNS change the renal handling of Na+? 2.) if so,
what changes in hemodynamic and hormonal modulators of renal
Na+ handling are correlated with these alterations? 3.) Do blacks
and whites differ in ENa+ changes induced by arousal and, if so,
are the correlations different? 4.) Are the associated SNS and
hormonal mechanisms associated with changes in ENa+
responsible for the changes in Na+ handling both during and
following the arousal period? 5.) What is the relative role of
genetic and environmental factors on the response patterns? We
will study a total of 100 male twin pairs (50 will be black, 50 will
be white). There will be equal numbers of monozygotic and
dizygotic twins. The protocol we have developed induces SNS
arousal by challenging pairs of subjects to compete with each
other for one hour using computer based tasks. During this
protocol we will measure blood pressure and heart rate, renal
plasma flow (PAH), glomerular filtration rate (creatinine or
inulin), proximal Na+ reabsorption (lithium clearance), total ENa+,
plasma renin activity, aldosterone and cortisol to evaluate how
SNS arousal reduces Na+ excretion and changes systemic and
renal hemodynamics before, during and after SNS arousal. Data
analyses using uni- and multivariate techniques will be used to
answer the questions posed.
Effective start/end date9/1/888/31/92


  • Medicine(all)


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