An automated data acquisition system for isolated tissue studies

Automated measurements of isolated heart muscle contractions: effects of halothane, calcium, and magnesium on guinea pig left atrial muscle

An in vitro method for automatically measuring muscle contraction force has been demonstrated in a study of the effects of the inhalation anesthetic halothane followed by calcium chloride or magnesium sulfate on isolated guinea pig left atrial muscle. An automated computer-controlled system was used to collect muscle contraction force waveforms and to analyze contraction waveforms for comparison of variables before and after drug administration. Two concentrations of halothane (0.5 and 1.5%) were administered to the atrial preparation for 30 minutes and followed by calcium chloride or magnesium sulfate. Six variables (latency, time to peak tension, peak tension, maximum rate of change of pressure, force time integral, and relaxation time) were automatically determined from averaged stimulus-response curves. Results were normalized and compared with controls administered only calcium and magnesium and with controls administered no drugs. The automated system greatly simplified data collection and accumulation and statistical analysis of multiple responses. The system made possible averaging and analysis of more data with less variability than is normally obtained with manual systems. The results confirm several known actions of these agents. Halothane prolongs latency (9 and 21% for 0.5 and 1.5% halothane, respectively) and shortens time to peak tension (6 and 17% for 0.5 and 1.5% halothane, respectively) and relaxation time (17 and 39% for 0.5 and 1.5% halothane, respectively). At high halothane concentrations (1.5%) calcium chloride shortens latency (10%) and prolongs time to peak tension (11%); magnesium sulfate prolongs latency (14%) and shortens time to peak tension (10%).

A fully automated system using a microcomputer for the hypertensive activity assays of drugs in the anesthetized rat

A complete system is described for the computerized automation of the determination of activity of hypertensive drugs in the anesthetized rat. The microcomputer used was the Apple IIe, and the automation was performed by a purpose-designed command module. The series of injections of hypertensive drugs was controlled by the microcomputer through the intermediary of the command module. All processing of the signal (hypertension peak), calculation of the data obtained, statistical processing, and archive storage of the results was carried out entirely by the microcomputer. The computer was able unaided to control three work stations simultaneously without requiring synchronization.