A perpetual switching system in pulmonary capillaries

Wiltz W. Wagner, Eric M. Jaryszak, Amanda J. Peterson, Claire M. Doerschuk, H. Bohlen, Judy A.C. King, Judith A. Tanner, Edward S. Crockett, Robb W. Glenny, Robert Presson

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Of the 300 billion capillaries in the human lung, a small fraction meet normal oxygen requirements at rest, with the remainder forming a large reserve. The maximum oxygen demands of the acute stress response require that the reserve capillaries are rapidly recruited. To remain primed for emergencies, the normal cardiac output must be parceled throughout the capillary bed to maintain low opening pressures. The flow-distributing system requires complex switching. Because the pulmonary microcirculation contains contractile machinery, one hypothesis posits an active switching system. The opposing hypothesis is based on passive switching that requires no regulation. Both hypotheses were tested ex vivo in canine lung lobes. The lobes were perfused first with autologous blood, and capillary switching patterns were recorded by videomicroscopy. Next, the vasculature of the lobes was saline flushed, fixed by glutaraldehyde perfusion, flushed again, and then reperfused with the original, unfixed blood. Flow patterns through the same capillaries were recorded again. The 16-min-long videos were divided into 4-s increments. Each capillary segment was recorded as being perfused if at least one red blood cell crossed the entire segment. Otherwise it was recorded as unperfused. These binary measurements were made manually for each segment during every 4 s throughout the 16-min recordings of the fresh and fixed capillaries (60,000 measurements). Unexpectedly, the switching patterns did not change after fixation. We conclude that the pulmonary capillaries can remain primed for emergencies without requiring regulation: no detectors, no feedback loops, and no effectors—a rare system in biology.

Original languageEnglish (US)
Pages (from-to)494-501
Number of pages8
JournalJournal of Applied Physiology
Volume126
Issue number2
DOIs
StatePublished - Feb 1 2019

Fingerprint

Lung
Emergencies
Switch Genes
Oxygen
Video Microscopy
Systems Biology
Glutaral
Microcirculation
Cardiac Output
Canidae
Perfusion
Erythrocytes
Pressure

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

Cite this

Wagner, W. W., Jaryszak, E. M., Peterson, A. J., Doerschuk, C. M., Bohlen, H., King, J. A. C., ... Presson, R. (2019). A perpetual switching system in pulmonary capillaries. Journal of Applied Physiology, 126(2), 494-501. https://doi.org/10.1152/japplphysiol.00507.2018

A perpetual switching system in pulmonary capillaries. / Wagner, Wiltz W.; Jaryszak, Eric M.; Peterson, Amanda J.; Doerschuk, Claire M.; Bohlen, H.; King, Judy A.C.; Tanner, Judith A.; Crockett, Edward S.; Glenny, Robb W.; Presson, Robert.

In: Journal of Applied Physiology, Vol. 126, No. 2, 01.02.2019, p. 494-501.

Research output: Contribution to journalArticle

Wagner, WW, Jaryszak, EM, Peterson, AJ, Doerschuk, CM, Bohlen, H, King, JAC, Tanner, JA, Crockett, ES, Glenny, RW & Presson, R 2019, 'A perpetual switching system in pulmonary capillaries', Journal of Applied Physiology, vol. 126, no. 2, pp. 494-501. https://doi.org/10.1152/japplphysiol.00507.2018
Wagner WW, Jaryszak EM, Peterson AJ, Doerschuk CM, Bohlen H, King JAC et al. A perpetual switching system in pulmonary capillaries. Journal of Applied Physiology. 2019 Feb 1;126(2):494-501. https://doi.org/10.1152/japplphysiol.00507.2018
Wagner, Wiltz W. ; Jaryszak, Eric M. ; Peterson, Amanda J. ; Doerschuk, Claire M. ; Bohlen, H. ; King, Judy A.C. ; Tanner, Judith A. ; Crockett, Edward S. ; Glenny, Robb W. ; Presson, Robert. / A perpetual switching system in pulmonary capillaries. In: Journal of Applied Physiology. 2019 ; Vol. 126, No. 2. pp. 494-501.
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