Adrenergic receptor mechanism of the human uterus

Abstract

Strips of human uterus, obtained during the caesarian operation, were isolated and taken into an organ bath to investigate the presence and behaviour of a- and /3-adre- nergic receptors in the human uterus at term. Noradrenaline, a pure a-adrenergic ago­ nist, enhanced the spontaneous activity. The effect was partially blocked by tolazoline and azapetine. Isoprenaline inhibited the uterine activity; this inhibition was suppressed by KO-592, a /^-blocking drug. Adrenaline, an a- and /3-receptor stimulant, increased consistently the spontaneous activity of the uterine strip. Blockade of a-receptors with tolazoline or azapetine reduced the effect of adrenaline. It is concluded that both, a- and /3-adrenergic receptors, are present in the human uterus at term. Stimulation of a-receptors results in an increase and that of /3-receptors in a decrease of the motor activity. There seems to be a functional predominance of the a-over the /^-receptors.