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Harumasa Yokota, Shinji Ono, Takayuki Kamiya, Chiemi Matsumoto, Akito Shimouchi, Taiji Nagaoka, Akitoshi Yoshida; The role of renin-angiotensin system in the regulation of retinal arterioles. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4355. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
It is proven that the renin-angiotensin system (RAS) directly induces vasomotor action in the coronary arterioles. However, direct vasomotor action of the RAS in the retinal circulation remains elusive. The aim of this study is to determine whether the RAS is crucial for vasomotor action in the retinal arterioles.
Porcine retinal arterioles were isolated, cannulated, and pressurized without flow in vitro. Changes in diameter were recorded using videomicroscopic techniques. To confirm the role of angiotensin II-dependent pathway, we assessed the change after incubation with angiotensin II with or without losartan or PD123319. To confirm the role of angiotensin II-independent pathway, we also assessed the change in diameter of retinal arterioles after incubation with human recombinant prorenin.
Angiotensin II (10-11~10-6M) neither constricted nor dilated the retinal arterioles. Pre-incubation of losartan (1uM) or PD123319 (50uM) didn’t result in any change in the diameter of retinal arterioles exposed to angiotensin II (10-11~10-6M). In addition, there was no vasomotor action in the retinal arterioles even after the incubation of prorenin (10-13~10-8M).
The current data clearly demonstrated that the RAS didn’t induce vasomotor action in the retina, suggesting that the regulation of retinal circulation could be totally independent of the RAS.
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