Pulmonary capillaries are recruited during pulsatile flow.

@article{Presson2002PulmonaryCA,
  title={Pulmonary capillaries are recruited during pulsatile flow.},
  author={Robert G. Presson and William A. Baumgartner and Amanda J. Peterson and Robb W. Glenny and Wiltz W. Wagner},
  journal={Journal of applied physiology},
  year={2002},
  volume={92 3},
  pages={
          1183-90
        }
}
Capillaries recruit when pulmonary arterial pressure rises. The duration of increased pressure imposed in such experiments is usually on the order of minutes, although recent work shows that the recruitment response can occur in <4 s. In the present study, we investigate whether the brief pressure rise during cardiac systole can also cause recruitment and whether the recruitment is maintained during diastole. To study these basic aspects of pulmonary capillary hemodynamics, isolated dog lungs… 

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