Studies on the cardiotoxicity of streptolysin O.

mg/20 g the day before, or calcium heparinate (calciparine) 0.1 ml./20 g intravenously 1 hr before-and were then anaesthetized with urethane 20 mg/20 g intraperitoneally. Needle electrodes pinning the animal by the paws were connected to the leads of a Sanborn 150 e.c.g. pre-amplifier. SM was injected intravenously in doses varying from 500 to 5,000 MHD50/20 g. Control experiments were carried out with non-active oxidized SM and the reducing agent. Similar experiments were performed on adult Wistar rats.