This paper describes three configurations of a now injection apparatus
designed to be the fluidic drive for perfusion studies of cultured ad
herent cells. The apparatus was coupled to a now-through perfusion cha
mber that was specifically designed for live cell perfusion using fluo
rescence microscopy as the detector. The instrument consists of two li
near syringe pumps and a multiposition selector valve which, under com
puter control, allowed sequential injection, fluid switching, and now
injection to be performed with minimal system reconfiguration. When th
e apparatus is coupled to a dual inlet perfusion chamber, target cells
can be exposed to very steep reagent pulses, while the traditional si
ngle inlet perfusion chamber allows more flexibility and provides a mo
re gradual increase in reagent concentration, The most significant sal
ient feature of the system is the ability to generate very steep pulse
s-a desirable feature for cell perfusion studies.