Adrenergic innervation and contractile activity of the mesotubarium superius of the rabbit oviduct.

Various patterns of spontaneous contractile activity were observed in the mesotubarium in vitro, but generally the frequency was lower and the amplitude was higher in the contractions than in those of the spontaneously motile oviduct. Contractile responses to norepinephrine occurred at concentrations higher than 10(-8) M. Twitch-like contractile responses were produced by field stimulation of 1 msec, 1-30 HZ and 100 V for 10sec. Responses to norepinephrine and electrical stimulation were inhibited by phentolamine or phenoxybenzamine, but were not affected by propranolol. Spontaneous contractile activity of the mesotubarium was diminished but the tonus was not affected by isoproterenol. These results suggest that the responses of the mesotubarium to norepinephrine and electrical stimulation are mainly related to the alpha-receptor rather than to the beta-receptor component.