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.