Abstract
Purpose :
Retinal vasomotion is spontaneous oscillations in the diameter of retinal arterioles. The consequent changes in retinal blood flow are considered to be important for oxygenation and fluid homeostasis. Nitric oxide (NO) has been shown to affect vasomotion in the porcine retinal arterioles in vitro. However, it remains unknown whether this response can be reproduced in humans in vivo.
Methods :
Video recordings of the retina were used to extract the diameter of a temporal retinal arteriole in 40 normal persons aged 20-30 years. Examinations were performed before and during inhibition of NO synthesis by intravenous infusion of L-NMMA and during donation of NO by sublingual nitroglycerine. Diameter changes over time were subjected to Fourier analysis with a calculation of the power of oscillations in the very low (VLF: 0.1-1.4 Hz), low (LF: 1.4-2.8 Hz), high (HF: 2.8-4.2 Hz), very high (VHF: 4.2-5.6 Hz) and ultra-high (HF: 5.6-23.7 Hz) frequency bands.
Results :
The baseline arterial diameter was significantly reduced by infusion of L-NMMA (p=0.005) but remained unchanged after administration of nitroglycerine (p=0.84). Neither L-NMMA nor nitroglycerine changed the amplitude of the oscillations in any of the studied frequency bands (p>0.052 for all comparisons).
Conclusions :
The power of diameter oscillations of a temporal retinal arteriole in vivo is unaffected by inhibition of NO-synthesis and by NO donoring. Vasoactive effects of NO on retinal vessels in vivo do not include the amplitude of vasomotion in larger arterioles.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.