June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
Thrombin causes biphasic regulation of vascular tone in porcine retinal arteries
Author Affiliations & Notes
  • Kengo Takahashi
    Ophthalmology, AsahikawaMedicalUniversity, Asahikawa, Japan
  • Taiji Nagaoka
    Ophthalmology, AsahikawaMedicalUniversity, Asahikawa, Japan
  • Tsuneaki Omae
    Ophthalmology, AsahikawaMedicalUniversity, Asahikawa, Japan
  • Shinji Ono
    Ophthalmology, AsahikawaMedicalUniversity, Asahikawa, Japan
  • Takayuki Kamiya
    Ophthalmology, AsahikawaMedicalUniversity, Asahikawa, Japan
  • Akira Tanner
    Ophthalmology, AsahikawaMedicalUniversity, Asahikawa, Japan
  • Akitoshi Yoshida
    Ophthalmology, AsahikawaMedicalUniversity, Asahikawa, Japan
  • Footnotes
    Commercial Relationships   Kengo Takahashi, None; Taiji Nagaoka, None; Tsuneaki Omae, None; Shinji Ono, None; Takayuki Kamiya, None; Akira Tanner, None; Akitoshi Yoshida, None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 3030. doi:
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    • Get Citation

      Kengo Takahashi, Taiji Nagaoka, Tsuneaki Omae, Shinji Ono, Takayuki Kamiya, Akira Tanner, Akitoshi Yoshida; Thrombin causes biphasic regulation of vascular tone in porcine retinal arteries. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3030.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Thrombin, a serine protease, plays an important role in hemostasis by converting fibrinogen to fibrin. In the vasculature, thrombin had been reported to cause vasodilation, whereas a previous study reported that thrombin causes vasoconstriction in bovine retinal arteries. However, the effect of thrombin on the retinal microcirculation remains unclear. We examined the effects of thrombin on the retinal microvasculature and investigated the signaling mechanisms.

Methods : Porcine retinal arterioles were isolated, cannulated, and pressurized (55 cm H2O) without flow for this in vitro study. Videomicroscopic techniques were used to record the changes in diameter in the retinal arterioles in response to thrombin at concentrations of 0.001 mU/ml to 20 mU/ml.

Results : Thrombin induced a concentration-dependent vascular response, i.e., initially vasoconstriction at a low concentration (<5 mU/mL) and then vasodilation at a high concentration (>5 mU/mL). Pretreatment with a protease-activated receptor (PAR)-1 inhibitor but not a PAR-2 or PAR-4 inhibitor significantly (p<0.01) suppressed thrombin-induced constriction. Endothelial denudation suppressed vasodilation caused by a high concentration of thrombin.

Conclusions : The current findings suggested that the low dose of thrombin causes vasoconstriction via a PAR-1 on smooth muscle, and the high dose of thrombin causes endothelium-dependent vasodilation in the retinal arterioles.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

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