The testosterone content of human spermatic vein blood

Abstract

The intracellular microelectrode was utilized to study the depolarization-repolarization process in guinea pig hearts with induced ventricular arrhythmias. Hearts with a ligature about the AV groove were placed in oxygenated Tyrode’s solution. Recordings were made from superficial ventricular cells. Application of aconitine crystals to the ventricular surface regularly produced fibrillation. In most of the preparations a transient period of ventricular tachycardia preceded the development of fibrillation. During the period of tachycardia, alternation in the amplitude of action potentials was frequently seen. In any single preparation electrical alternation could be recorded from several cells, although not all cells exhibited this phenomenon. Within ten to fifteen minutes ventricular fibrillation ensued. Comparison of action potentials from cells of various areas revealed variations in their rate and amplitude. As time elapsed, complete depolarizations became less frequent and the pattern of action potentials of small amplitude at the rate of 500 to 900 per minute resulted. These studies suggest that electrical alternans seen in the electrocardiogram may be related to alternation in amplitude of action potentials in a great number of singIe myocardial cells. They also indicate that in ventricular fibrillation, single myocardial cells participate in disorganized electrical activity in the form of irregular and incomplete action potentials.