Spontaneous electrical activity of the rat epididymis in vitro

Abstract

Smooth muscle electrical activity was recorded with suction electrodes from the partly or completely uncoiled epididymal duct of the rat in vitro. The electrical activity of the cauda epididymidis consisted of one or few spikes followed by a plateau of 1-2 sec. The frequency of electrical activity declined from the thicker-walled initial segment of the thin-walled initial segment, was increased to the level seen in the initial segment in the thicker, major portion of the caput epididymidis, declined in the corpus and fell steeply in the cauda epididymidis towards the vas deferens. Electrical activity spread over long distances in the distal cauda and epididymal vas. Elsewhere in the epididymis activity remained synchronous only for a short period in short segments.

Effects of oxytocin and vasopressin on electrical and mechanical activity of the rat epididymis in vitro

“…Electrical recording only was used in the caput because of the thinness of its muscle layers. The pretreatment activities of the caput and cauda agree well with those of the study of Talo et al (1979), when the 2-5°C lower temperature of the present study is considered (Jaakkola & Talo, 1980). The concentration (4 10_1 mU/ml) of vasopressin that increased significantly the frequency of the electrical and mechanical activity in the caput and cauda was about the same as that used by Hib (1975) to increase the frequency and basal tension of the activity of the distal end of the epididymis of the mice.…”

Movements of the luminal contents in two different regions of the caput epididymidis of the rat in vitro.

“…No direct conclusion concerning the electrical activity of the wall musculature, however, can be drawn from the movements of the epididymal contents, since activity may spread over distances longer than the actual movement of the epididymal contents. But the frequency of the pendular movements corresponded to that of electrical activity in these regions of the caput (Talo et al 1979) when the temperature in this study, about 2-5 deg C lower, is taken into account (Jaakkola & Talo, 1980); and in most cases the direction of Al was the same as the direction ofthe spreading contractions. Thus the linear correlation found in the cauda between the distance of net transport and the probability of the spread of activity towards the ductus deferens (Jaakkola & Talo, 1982) is comparable to the correlations found in this study between the net transport distance and the probability of Al being in the direction of the ductus deferens.…”

“…The lower transport speed through the cauda than the caput epididymidis (Amann et al 1976) may result from the lower frequency of the contractions (Talo et al 1979) and from the lower probability of spread ofelectrical activity (Jaakkola & Talo, 1982) and occurrence of Al towards the ductus deferens. The longer Al values during fast transport, and the higher probability and higher frequency ofthe pendular movements in region I compared with those in region II of the caput may lead to a higher speed of transport in this region, agreeing closely with the results found in vivo by Macmillan & Aukland (1960).…”

“…Region I consisted of the most proximal part of the caput epididymidis, wider in outer diameter and about 20 cm long; region II consisted of the next and narrowest portion of the caput epididymidis, about 80 cm long. These two regions differ in the frequency of their muscular activity (Talo et al 1979).…”

“…In the most distal part of the epididymis, electrical activity may spread over several centimetres, while in the other regions the distance of spread may be very limited (Talo, Jaakkola & Markkula-Viitanen, 1979). In the cauda epididymidis, spread of electrical activity is associated with movements of the luminal contents (Jaakkola & Talo, 1982).…”