Studies of the adrenergic reactivity in different regions of rabbit and rat oviduct.

Experiments are made to study the spontaneous contractions and the contractile response to noradrenaline of muscle strips isolated in longitudinal direction from the ampulla, isthmus and horn of the oviduct. Left oviduct of rats (in oestrus and dioestrus) and rabbits (in dioestrus) was used. In both rats and rabbits, all muscle strips including the ovarium manifest spontaneous contractions with highest frequency in the ovarium and ampulla, lower in the isthmus and lowest in the horn. Noradrenaline inhibits spontaneous contractions of strips in rat oviduct and ovarium. The inhibitory effect is manifested at lower noradrenaline concentration for the horn and isthmus (maximum effective concentration 3 X 10(-7) M in dioestrus and 3 X 10(-6) M in oestrus) compared with the ampulla and the ovarium (3 X 10(-6) M in dioestrus and 3 x 10(-5) in oestrus). Noradrenaline stimulates rabbit oviduct contractions . The stimulating response is manifested at lower noradrenaline concentration (1 X 10(-8) M minimum effective concentration) for the isthmus, higher for the horn (5 X 10(-7) M) and highest for the ampulla (5 X 10(-6) M). The presence of different alpha- and beta-adrenergic reactivities in the different areas of the oviduct is discussed.