In the present study we aimed to assess the effect of α1-adrenoceptor blockade on resting and hyperemic myocardial blood flow in normal humans. Myocardial blood flow, at baseline and after dipyridamole, was measured with positron emission tomography and 15O-labeled water in 11 normal volunteers at control and during α1-blockade with doxazosin. Baseline myocardial blood flow during α1-blockade was not different from control, whereas 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, myocardial blood flow during α1-blockade 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-1g-1; P <0.01) compared with control. In conclusion, in normal humans, dipyridamole-induced increase in myocardial blood flow is limited by α1-mediated coronary vasoconstriction.
|Journal||American Journal of Physiology - Heart and Circulatory Physiology|
|Publication status||Published - Oct 1996|
- Autonomic nervous system
- Coronary resistance
- Positron emission tomography
ASJC Scopus subject areas