THE ISOLATED ACID PERFUSED WORKING HEART OF THE FROG, RANA-ESCULENTA - AN IMPROVED PREPARATION

1. An in vitro preparation of the intact heart of the frog Rana escule nta was set up. 2. The isolated heart, perfused at constant pressure, was spontaneously beating and able to generate physiological values of output pressure, cardiac output, ventricle work and power. It showed the typical phenomenon of the ''hypodynamic state'' after a relatively constant time from the onset of the perfusion. 3. Perfusion with air- saturated saline and 99.5% oxygen-saturated saline did not show signif icant differences in the recorded parameters. 4. This experimental mod el represents a useful tool for physiological and pharmacological stud ies, especially when the direct analysis of the effects of hormones, m ediators or drugs requires an intact heart preparation.