Fully automated experiments with isolated organs in vitro.

A fully automated system for pharmacological in vitro experiments with isolated tissues is described. The apparatus consists of an organ bath equipped with a) a gradient pump supplying a logarithmic concentration/time gradient of agonist; b) pumps and valves for dispensing bath fluid, antagonist solutions, and an oxygenation gas mixture; and c) a transducer with automatic baseline adjustment. The information coming from the preparation (i.e., changes in length or tension) is fed into a DEC PDP-11 mini-computer (MINC). This computer controls the test procedure either directly (e.g., when to break off the logarithmic gradient) or indirectly after processing the information in the form of log-concentration response curves (e.g., when to repeat a given procedure, or when to stop the experiment). At the end of the experiment, the results are presented both alpha-numerically and graphically. The data of various experiments can be accumulated and Schild-plots obtained. The example given demonstrates that this automated method offers considerable advantages over the classical manual method in that it has far greater precision. By careful planning, using several set-ups simultaneously with different isolated organs from the same animal, the investigator can carry out various experiments 24 hr a day and also reduce the number of sacrificed animals.