Real-time observation of hemodynamic changes in glomerular aneurysms induced by anti-Thy-1 antibody

Background. Blood flow in the microvasculature plays a pivotal role in dete rmining the outcome of injury and repair in inflamed tissue. Real-time obse rvation of the kidney microvasculature, including the glomerular capillary tufts, is extremely difficult because of the methodological limitations of currently available microscope optics. In the present study, we attempted t o analyze hemodynamic events that occurred in vivo during microvascular reg eneration following destruction of the glomerular capillary tuft, functiona lly and quantitatively by the use of a real-time confocal laser-scanning mi croscope (CLSM) system. Methods. A polyethylene catheter was inserted into the carotid artery to al low blood pressure measurement. Mesangiolytic lesions producing microaneury sms were induced by the injection of anti-Thy-1.1 antibody. On days 3 and 7 after antibody injection, we examined hemodynamic changes under an intravi tal microscope equipped with real-time CLSM in combination with a high-spee d CCD video camera. To measure vessel diameter and erythrocyte velocity, ra ts were injected with fluorescein isothiocyanate (FITC)-labeled dextran and FITC-labeled red blood cells (RBCs). Results. On day 3 of the disease, mean arterial blood pressure was 112 +/- 5 mm Hg, which was significantly higher than that of normal rat or of rats on day 7 (93 +/- 1 and 101 +/- 9 mm Hg. respectively). Within mircroaneurys ms on day 3, RBC velocity was greatly suppressed. By day 7, RBC velocity, i n glomeruli with normal appearances, recovered to about half of the level s een in normal controls (430.6 +/- 284.7 mum/sec), while in narrowed glomeru lar tufts, it was still only 104.6 +/- 35.1 mum/sec. Conclusions. The noninvasive procedure, using CLSM in combination with a hi gh-speed video camera, allowed us to examine hemodynamic events quantitativ ely and to analyze microvascular architecture three dimensionally in the ki dney. It is useful for estimating hemodynamic response and vascular regener ation in vivo and may be promising for clinical application.