Simultaneous recording of electrical and mechanical activity in isolated smooth muscle of the human oviduct

Small strips from the circular muscle layer at the ampullary-isthmic junction of the human oviduct were suspended in an organ bath. Mechanical activity was recorded isometrically by a force displacement transducer and electrical activity was registered simultaneously by an extracellular glass-silver electrode. Spontaneous contractions were not associated with "burst" of action potentials but were preceded by a single spike with a duration of approximately 700 milliseconds. During the rest of the contraction there was a total absence of potential changes. Prostaglandin E2 (PGE2) abolished spike discharge leading to inhibition of mechanical activity. Prostaglandin F 2 alpha (PGF 2 alpha), on the other hand, increased the rate of action potentials and, hence, the frequency of contraction. However, neither PGE2 nor PGF2 alpha changed the configuration of the spike. It is concluded that in smooth muscle of the human oviduct, there is a high degree of agreement between the electrical and mechanical signals and that prostaglandins act by reducing or increasing the rate of spike discharge but not by influencing the character of the action potential.