Direct observation of epicardial coronary capillary hemodynamics during reactive hyperemia and during adenosine administration by intravital video microscopy

Takahiko Kiyooka, Osamu Hiramatsu, Fumiyuki Shigeto, Hiroshi Nakamoto, Hiroyuki Tachibana, Toyotaka Yada, Yasuo Ogasawara, Masahito Kajiya, Taro Morimoto, Yuki Morizane, Satoshi Mohri, Juichiro Shimizu, Tohru Ohe, Fumihiko Kajiya

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34 Citations (Scopus)

Abstract

Using high-resolution intravital charge-coupled device video microscopy, we visualized the epicardial capillary network of the beating canine heart in vivo to elucidate its functional, role under control conditions, during reactive hyperemia (RH), and during intracoronary adenosine administration. The pencillens video-microscope probe was placed over capillaries fed by the left anterior descending artery in atrioventricular-blocked hearts of open-chest, anesthetized dogs paced at 60-90 beats/min (n = 17). In individual capillaries under control conditions, red blood cell flow was predominant during systole or diastole, indicating that the watershed between diastolic arterial and systolic venous flows is located within the capillaries. Capillary flow increased during RH and reached a peak flow velocity (2.1 ± 0.6 mm/s), twice as high as control (1.2 ± 0.5 mm/s), with enhancement of intercapillary cross-connection flow and enlargement of diameter (by 17%). With adenosine, capillary flow velocity significantly increased (1.8 ± 0.7 mm/s). However, the increase in volumetric capillary flow with adenosine estimated from red blood cell velocity and diameter was less than the increase in arterial flow, whereas that during RH was nearly equivalent to the increase in arterial flow. There was a time lag of ≃1.5 s for refilling of capillaries during RH, indicating their function as capacitance vessels. In conclusion, the coronary capillary network functions as 1) the major watershed between diastolic-dominant arterial and systolic-dominant venous flows, 2) a capacitor, and 3) a significant local flow amplifier and homogenizer of blood supply during RH, but with adenosine the increase in capillary flow velocity was less than the increase in arterial flow.

Original languageEnglish
Pages (from-to)H1437-H1443
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume288
Issue number3 57-3
DOIs
Publication statusPublished - Mar 2005

Keywords

  • In vivo imaging
  • Microcirculation
  • Unstressed volume
  • Watershed

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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    Kiyooka, T., Hiramatsu, O., Shigeto, F., Nakamoto, H., Tachibana, H., Yada, T., Ogasawara, Y., Kajiya, M., Morimoto, T., Morizane, Y., Mohri, S., Shimizu, J., Ohe, T., & Kajiya, F. (2005). Direct observation of epicardial coronary capillary hemodynamics during reactive hyperemia and during adenosine administration by intravital video microscopy. American Journal of Physiology - Heart and Circulatory Physiology, 288(3 57-3), H1437-H1443. https://doi.org/10.1152/ajpheart.00088.2004