IN-VIVO MEASUREMENT OF MORPHOMETRIC AND HEMODYNAMIC-CHANGES IN THE MICROCIRCULATION DURING ANGIOGENESIS UNDER CHRONIC ALPHA(1)-ADRENERGIC BLOCKER TREATMENT

The effect of chronic administration of the alpha 1 blocker prazosin o n microvascular angiogenesis was studied in rabbit ear chamber to inve stigate the role of concomitant increase in now-oriented wall shear st ress in vascular remodeling during angiogenesis. Rabbits were treated with pm zosin hydrochloride (50 mg/liter in water) orally after ear ch ambers were installed. The microcirculation in the chamber was observe d and recorded from 4 to 23 postoperative day (POD) by an intravital v ideomicroscope. The total vascular area (TA) were quantified as a morp hometric parameter. Changes in wall shear stress in venules (20-40 mu m ID) were calculated from flow velocity, vessel diameter, and in vivo blood viscosity. TA was significantly increased in the prazosin-treat ed animals. The levels of shear stress, which was increased 1.43 times by prazosin on 9 POD, gradually decreased toward the control level on 13 POD and they almost coincided on 21 POD. These findings experiment ally provided supporting evidence that shear stress is probably involv ed in the adaptive response as one of mechanical factors regulating va scular remodeling during angiogenesis. (C) 1998 Academic Press.