Kinetic and morphometric measurements of enzyme reactions in tissue sections with a new instrumental setup.

An instrumental setup is described for the measurement of enzyme kinetics and morphometry in tissue sections. It consists of a Vickers M85 microdensitometer and computer-assisted Kontron Videoplan system. The Videoplan system consists of a minicomputer with two mini-floppy disks, a keyboard, a graphic tablet, a TV monitor and a printer/plotter. The measuring component of the M85 is linked to the minicomputer via a BCD interface, and the optical system of the M85 is coupled to a TV camera for display on the monitor screen. The enzyme-kinetic data obtained with the M85 in a specified area of the tissue section (density values as a function of reaction time) are stored in the minicomputer. The measurement process is controlled by a corresponding measuring program. Through correlation analysis (a component of the commercial software) between density values and reaction time, the initial and thus maximum enzyme activity is determined. Upon completion of the kinetic measurements, the measured area of tissue is transferred by the TV camera to the monitor, and the reaction area is described and measured with the graphic tablet in video dialogue and related to the initial enzyme activity. With the setup described, it is possible to make microdensitometric measurements of enzyme activities in a specified tissue area while morphometrically analyzing the associated reaction area. To illustrate the use of the system, enzyme-kinetic (succinate dehydrogenase) and morphometric measurements are performed in tissue sections from the proximal tubule of the rat nephron. Additional applications of the system are discussed.