Abstract:A new method for the quantitative measurement of fluorescent intensity of the rat's liver surface after fluorescein injection is described. The measuring system of fluorescent intensity on the rat liver surface consisted of a video laparoscopy with a video densitometer. An excitation filter was placed in the light source and an absorbing filter was attached to the eyepiece of the magnifying scope in this fluorescence video laparoscopy system. Fluorescein was injected intravenously into the inferior vena cava. Video fluorescence images of the liver surface were recorded with a CCD TV camera which was connected to the scope. In measuring the mean intensity of video images, a region of interest was designated on the TV monitor. The fluorescent intensity in this region was measured by a video densitometer and expressed in volts. The time‐intensity curve was graphically presented using a pen recorder. In this way, the time course of the liver surface fluorescent intensity could be analyzed with data expressed in volts. In normal livers, the fluorescent intensity began to rise 4.0 ± 0.5 seconds after fluorescein injection and reached a peak at 14.4 ± 1.5 seconds. Thereafter, the intensity fell slightly but then rose again to a second peak 170±50 seconds after injec