Effect of [alpha]1 adrenoceptor blockade on resting and hyperemic
myocardial blood flow in normal humans.
Lorenzoni, Roberto, Stuart D Rosen, and Paolo G Camici.
MRC Clinical Sciences Centre and Royal Postgraduate Medical School,
Hammersmith Hospital, London W12 ONN, United Kingdom
APStracts 3:0040H, 1996.
In the present study we aimed to assess the effect of [alpha]1
adrenoceptor blockade on resting and hyperemic myocardial blood flow
in normal humans. Myocardial blood flow, at baseline and after
dipyridamole, was measured in 11 normal volunteers with positron
emission tomography and 15O-labelled water, at control and during
[alpha]1 blockade with doxazosin. Baseline myocardial blood flow,
during [alpha]1 blockade, was not different from control while
coronary resistance was significantly lower (73.48+/-18.31 vs
89.84+/-27.96 mmHg.min.ml-1.g-1; p<0.05). After dipyridamole,
during [alpha]1 blockade, myocardial blood flow was significantly
higher (3.50+/-0.75 vs 2.58+/-0.54 ml.min-1.g-1; p<0.01) and
coronary resistance lower (25.30+/-7.37 vs 33.89+/-7.04 mmHg.min.ml
-1.g-1; p<0.01) compared to control. In conclusion, in normal
humans, dipyridamole-induced increase in myocardial blood flow is
limited by [alpha]1-mediated coronary vasoconstriction.
Received 11 September 1995; accepted in final form 9 January
1996.
APS Manuscript Number H854-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 29 January 96