Title page for ETD etd-07282008-135332
|Type of Document
||Franke, Warren D
||Effects of α1-receptor blockade on the hemodynamic responses to exercise in young normotensives and hypertensives
||Educational Research and Evaluation
|Herbert, William G.
|Cross, Lawrence H.
|Gwazdauskas, Francis C.
|Humphrey, Reed H.
|Kenner, W. Larry
|Southard, Douglas R.
|Date of Defense
The purpose of this study was to determine if α1-
adrenergic receptor blockade alters the hemodynamic response
to exercise in young (<25 yr) male adult borderline
hypertensives differently than in young normotensives. Five
hypertensive (HTN, MAP>105 mmHg) and 7 normotensive (NTN,
MAP<95 mmHg) college-age males underwent two 30 min bouts of
cycle ergometry exercise at 50% V02Pk in a warm (25°C, 50%
rh) environment; one bout occurred followed α1-receptor
blockade with prazosin (HTN-α, NTN-α) and the other
following placebo administration (HTN-p, NTN-p). At rest,
HTN-p exhibited an elevated cardiac output (Q, p=.024) and
MAP (p=.007). Resting Q was similar for HTN-α and NTN-α.
Resting heart rate (HR) was elevated more in HTN-α than NTNα
(p=.013) and not different for placebo. Resting and
exercise forearm blood flows were similar between groups and
altered similarly with prazosin. Exercise resulted in
greater (p=.035) Q for HTN vs NTN (HTN-u > NTN-α; HTN-p =
NTN-p). HR was higher (p=.043) with prazosin for both
groups. Regardless of drug treatment, MAP was stable for
NTN while it declined after 10 min of exercise in HTN.
Rectal temperatures rose above baseline after 10 min. since
Q was similar between groups with placebo but not with α1-
blockade, and FBF, MAP, and HR were similarly altered
between drug trials, it was concluded that young male
hypertensives have an elevated blood pressure due to an
elevated Q. In this group, α1-blockade may reduce Q by
reducing central venous return.
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