The effects of phenoxybenzamine on the aortic pressure-diameter relationship in dogs.

The normalized diameter (D/D13.3 where D13.3 equals D at 13.3 kPa under control conditions) was measured at selected pressure levels under different hemodynamic conditions. Hemorrhage caused the normalized diameter to decrease (-3.3%) when compared to control values at a given pressure. Volume expansion and alpha-blockade with phenoxybenzamine caused D/D13.3 to increase (+3.3% and +8.5% respectively).