Wd. Franke et Sn. Lavere, EFFECTS OF ALPHA(1)-BLOCKADE ON THE FOREARM VASCULAR-RESISTANCE RESPONSES TO LOWER-BODY NEGATIVE-PRESSURE IN YOUNG BORDERLINE HYPERTENSIVES, American journal of hypertension, 10(8), 1997, pp. 893-898
To determine whether alpha(1)-blockade affects the forearm vascular re
sistance responses to lower body negative pressure (LBNP) in borderlin
e hypertensives, six hypertensives (HTN; mean arterial pressure [MAP]
= 109.9 +/- 1.7 mm Hg, mean a SE) and seven normotensives (NTN; MAP =
81.5 +/- 1.4 mm Hg) underwent exposures of LBNP at pressures of -10, -
20, and -40 mm Hg during systemic alpha(1)-receptor blockade (BLK) and
during placebo (PLA). Resting forearm vascular resistance (FVR) was g
reater in HTN than in NTN during PLA (34.8 +/- 5.4 v 17.5 +/- 3.1 unit
s; P < .05), but not during BLK (28.1 +/- 5.2 v 25.3 +/- 9.9 units). W
hen expressed as a percentage of resting FVR, LBNP evoked an increased
FVR (P < .001) that did not differ significantly between BLK and PLA
in either group. FVR was higher (P < .001) in HTN than in NTN througho
ut both trials; at -40 mm Hg of LBNP during BLK, the increase in FVR w
as greater (P < .05) in HTN than in NTN (131 +/- 42 v 48 +/- 15%). MAP
(relative to resting) was maintained throughout LBNP during PLA but,
at -40 mm Hg, was lower (P < .01) during BLK for both groups. HR was e
levated in BLK and was increased at -40 mm Hg (P < .01) for each group
in each trial. This increase was greater during BLK (P < .05). These
data suggest that borderline hypertensives have a greater vasoconstric
tor response to LBNP than do normotensives and cu,blockade does not ap
pear to attenuate this response. (C) 1997 American Journal of Hyperten
sion, Ltd.