An inexpensive electronic digital integrator suitable for use with isolated tissues.

The development and use of an electronic integrator suitable for use with isolated tissues is described. The design of the apparatus enables a multichannel integrator to be built from easily obtainable components at a relatively low cost while having accuracy and stability not previously available from circuits designed for such applications. The design includes a Schmitt trigger for positive reset of the integrator section, a chopper type linear amplifier, an electronic digital totalizing counter with seen segment LED readout, and the inclusion of an FET device as the discharge element. The addition of a polarity change switch accommodates both relaxatory and contractile responses. A switched attenuator enables 0-10 mV, 0-100 mV, 0-1 V, and 0-14 V ranges of input to be covered. The integrator enables accurate quantitation of contractile and relaxatory responses and also allows myogenic activity to be measured whatever the time course of these responses. This integrator thereby provides an accurate alternative to the usual quantitative measurements determined from isolated tissues.