Is the primary peristaltic contraction of the canine esophagus bolus-dependent?

@article{Janssens1973IsTP,
  title={Is the primary peristaltic contraction of the canine esophagus bolus-dependent?},
  author={Jozef Janssens and Pierre Valembois and Gaston Vantrappen and Jan Hellemans and Walter Pelemans},
  journal={Gastroenterology},
  year={1973},
  volume={65 5},
  pages={750-6}
}