The Superfusion Cascade Bath permits testing of extremely small quantities of pharmaceuticals. Any metabolites or mediators released are passed to the subsequent test preparation and can become effective there. It is possible to test up to four preparations (muscle strips or isolated tissues). The preparations are contained in a thermostated chamber. A roller pump produces a small flow of solution (1 - 10 ml/min) which is warmed by a heat exchanger then drips on to the uppermost test preparation. There is a provision for switching between two different solutions. The effluate of each preparation passes in the form of a cascade onto the subsequent preparation. Any muscle contractions produced are measured by force transducers (isometric contraction measurement) or displacement transducers (isotonic contraction measurement).
The Superfusion Cascade Bath, as modified by SCHULER, consists of a moist acrylate chamber which is thermostated by radiant heat from a thermostated metal plate. Temperature control is provided by a thermostatic circulator. The four tissues are arranged in cascade so that each tissue receives its superfusion solution from the previous tissue through a small tube. These stainless steel tubes carry a ring to which the tissues are attached. Part of the tube is in the form of an open channel. The tubes can be moved in height (vertically) and also horizontally, ensuring optimum adjustment to suit the suspended tissues and allows superfusion free from any interruption. Mounting the tissues is simplified by the removable front panel of the chamber.