| Abstract: | The musculature of the oviduct consists of an outer, irregular layer of longitudinal muscle and an inner layer of circular muscle. The four basic modes of activity—compression, segmentation, peristalsis, and reverse peristalsis—were evident in the isolated oviduct. These spontaneous events often occurred in an organized sequence. In fact eggs could be transported down the lateral oviducts by this myogenic activity once the sphincter between the common oviduct and vagina was severed. Myographic recordings were made of only the contractions of the longitudinal muscles. L-glutamate caused a distinct phasic contraction at 2.2 × 10?5 M. The response became larger and more complex as the concentration of the amino acid was increased. Acetylcholine (1.6 × 10?5 M) caused either a phasic or tonic response, or a combination thereof. By contrast, 5HT and tyramine simply increased the frequency of small phasic contractions, although in some preparations both monoamines caused an inhibition. The ecdysones, a juvenile hormone analogue (1 × 10?6 M), and prostaglandin E2 had no effect on oviduct activity. Initially high KCI solutions (162 mM) without Ca++ induced a strong contraction but subsequent additions failed to do so. However, when a high KCI solution (158 mM) with 2 mM Ca++ was added to the preparation the response was partially restored. Also the potent calcium antagonist Mn++ (2mM) can suppress spontaneous activity. |
