Keywords
Abstract
The role of nitric oxide (NO), usually considered as a potent vasodilator, in regulating retinal neurovascular coupling is still elusive. Measurements of flicker light-induced functional hyperemia (FH) in humans show that an increase of NO levels reduces vasodilation. This evidence has led to conjecture that such an increase may be responsible for suppressing flicker-evoked vasodilation in diabetic retinopathy. In this paper, we propose a mathematical model to theoretically investigate the effect of an increase in neural NO (nNO) on the vasodilation of retinal arterioles. Simulation results indicate that nNO increase may:
1. significantly aff ect vasoconstrictive agent production by glial cells; and
2. elicit vasoconstriction rather than vasodilation in retinal arterioles.
Model predictions seem therefore to support the conjecture that NO increase may be responsible for suppressing flicker-evoked vasodilation in diabetic retinopathy.
References
Cardani A. Theoretical analysis of neurovascular mechanisms contributing to retinal blood flow regulation. Master Thesis, Politecnico di Milano, Italy, 2015.
Sacco R, Mauri AG, Cardani, A, Siesky BA, Guidoboni G, Harris A. Increased levels of nitric oxide may pathologically affect functional hyperemia in the retina: model and simulation. Posterboard Number 214 – B0245, Annual Meeting of the Association for Research in Vision and Ophthalmology, Baltimore MD, 2017.
Newman EA. Functional hyperemia and mechanism of neurovascular coupling in the retinal vasculature. J Cereb Blood Flow Metab. 2013; 33(11):1685–1695.
Metea MR, Newman EA. Glial cells dilate and constrict blood vessels: A mechanism of neurovascular coupling. J Neurosci. 2006; 26(11):2862–2870.
Hadfield J, Plank MJ, David T. Modeling secondary messenger pathways in neurovascular coupling. Bull Math Biol. 2013;75(3):428-443.
Kudryashov NA, Chernyasvskii IL. Numerical simulation of the process of autoregulation of the arterial blood flow. Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza. 2008;43(1):38-56.
Attwell D, Buchan AM, Charpak S, Lauritzen M, MacVicar BA, Newman EA. Glial and neuronal control of brain blood flow. Nature. 2010;468(7321):232–243.