The effect of oxytocin on blood vessels of cremaster muscle of the rat.

Oxytocin administered intravenously to the anaesthetized rat produced dilatation of the blood vessels of the cremaster muscle at concentrations ranging from 2.5 times 10-minus 11 to 2.5 times 10-minus 9 M. When applied topically to the exposed vessels it produced constriction at concentrations ranging from 2.5 times 10-minus 12 to 5.0 times 10-minus 8 M. Oxytocin was thus similar to adrenaline in eliciting opposite effects when applied to the serosa or to the intima of skeletal muscle blood vessels.