Distribution of Adrenergic Receptors in the Domestic Fowl Oviduct

Abstract

The effect of epinephrine, phenoxybenzamine (alpha-receptor blocker), and propranolol (beta-receptor blocker) on the oviductal motility in an in vitro system was investigated in strips from infundibulum, magnum, isthmus, and uterus from laying hens. Epinephrine resulted in a significant (P less than .05) contraction of both infundibulum (+166.6%) and magnum (+70.3%) and relaxation of the uterus (-56.9%), while the response of the isthmus was inconsistent. Epinephrine induced contractions in propranolol blocked strips in all four oviductal segments studied (infundibulum, +138.1; magnum, +70.4; isthmus, +35.9; and uterus, +30.1%). Epinephrine, in phenoxybenzamine-blocked strips, resulted in relaxation of all segments (infundibulum, -27.5; magnum, -40.5; isthmus, -63.4; and uterus -53.6%). These results suggest that the activity of alpha-excitatory adrenergic receptors is greater in the anterior than in the posterior segment of the oviduct. conversely, greater activity of beta-inhibitory receptors seems to be present in the posterior than in the anterior segment of the oviduct.