Figure 4

Calculation and graphing of the emergence function, i.e., the rate of appearance of ¹²⁵I-activity in venous blood. 4A. The time-course of radioactivity concentration in arterial plasma after an intravenous bolus injection of ¹²⁵I-IGF-1. 4B. The emergence function calculated from the arterial plasma concentration-time curve following intravenous injection plus the arterial plasma curves following intraventricular and intraparenchymal infusions. The emergence function is the rate of appearance of the radioactivity in the venous system (dpm/min) and was calculated for 2.5, 7.5, 15, 25, 37.5, 52.5, and 75 min; the breakpoints on the graphs demarcate these times after infusion. The curves were not smoothed although the rates continually change throughout the period of interest.