Recent studies have demonstrated that prolonged induced cardiac arrest is followed by myocardial damage1,2 and depressed ventricular function3 in the dog. It has also been shown that this depression may be limited by prophylactic digitalization4 and by hypothermia.5' The present communication reports our experiences with the use of mephentermine sulfate (Wyamine), a cardiotonic and pressor agent,6 in dogs in which myocardial function has been depressed by a 30-minute period of asystole induced by potassium citrate.
Methods
Mongrel dogs of 8.5 to 12.5 kg. body weight were used. Anesthesia was induced by intravenous thiopental sodium. Complete respiratory paralysis was obtained with intravenously administered succinylcholine. The animals were respired7 with 100% oxygen at pressures of 15 to 20 cm. water. Esophageal temperature was recorded by a thermistor probe.Femoral arterial pressure was measured by means of a P23A Statham transducer. Arterial blood was sampled by way