Electrovasogram: A canine study of the electromechanical activity of the vas deferens

Abstract

To study the electric activity of the vas deferens (VD), or electrovasogram (EVG), in 14 mongrel dogs. The VD was exposed in the spermatic cord and three electrodes were applied to it. Synchronous transcutaneous EVG was also recorded by another three electrodes. The electric activity and intravasal pressure (IVP) were determined at rest, during ejaculation, and after vasal myotomy. Slow waves or pacesetter potentials (PPs) were recorded regularly from all electrodes applied to the VD whether directly or transcutaneously. They had identical frequency and regular rhythm from all the electrodes and were consistent in the individual dog on all test days. Action potentials (APs) followed PPs randomly and were associated with an IVP increase, indicating a state of contractile activity. Just before ejaculation, the PPs and APs increased significantly (P < 0.05) and were associated with IVP rise (P < 0.01). During ejaculation, there was rhythmic increase of the PPs, APs, and IVP (P < 0.01 for frequency and amplitude, P < 0.05 for velocity of PPs and P < 0.001 for IVP) followed by a silent period and return to the resting activity (P > 0.05). After vasal myotomy, PPs and APs were recorded proximal but not distal to the cut. This suggests that the PPs and APs spread caudally from the proximal part of the VD that is believed to be the site of a pacemaker that triggers the PPs. The PPs seem to pace the vasal contractile activity in terms of direction and frequency. A normal EVG pattern was characterized for the VD, which may be deranged in the various vasal pathologic conditions. EVG may thus be proposed to be included as an investigative tool in the diagnosis of vasal disorders.