BIPHASIC ACTION OF 5-HYDROXYTRYPTAMINE AND ADRENALINE, AND COMPARATIVE SENSITIVITY TO 5-HYDROXYTRYPTAM INE AND CATECHOL-AMINES IN ISOLATED FROG HEARTS

Abstract

A specially designed experimental set up with transducers, integrating circuits, a four channel recorder and other electronic assemblies, was developed to monitor and record very small changes in cardiac output, arterial pressures, heart rate and venous (perfusion) pressure of spontaneously beating isolated perfused frog hearts. The sensitivity of the method permitted recording of actions of very small quantities of acetylcholine in a concentration as low as 10^-19 g/ml (1, 2). The study was extended to other neurohumoral transmitters. This paper reports the results of investigation on the action of 5-hydroxytryptamine, adrenaline and noradrenaline.