Real-time evaluation of systemic-ocular microcirculation using laser speckle flowgraphy in white rabbits

Abstract

Purpose : To establish systemic-ocular microcirculation using laser speckle flowgraphy (LSFG) in white rabbits and investigate the circulatory response to a systemic adrenaline load.

Methods : We used six normal adult male New Zealand white rabbits (16 weeks of age, 2.8–3.3 kg). After intramuscular administration of xylazine (5 mg/kg) and ketamine (35 mg/kg), the rabbits were intubated and administered vaporized isoflurane (1.5-2.0%, room air 2 L/min). Surgical indwelling needles were inserted into the right and left auricular veins; these were used for infusion and drug administration. Heparinized arterial cannulas were placed in the right brachial and right rectal arteries for measurement of blood pressure while the blood flow rates of the right femoral artery and the left common carotid artery were measured using laser Doppler to determine blood flow volume in each artery. Mean blur rate (MBR) of the retinal vessels and choroid area were measured using LSFG-rabbit™ (Softcare, Fukuoka, Japan), developed for animals. Continuous intravenous adrenaline (0.2 mL/kg /min; 100-1000 ng/kg) was administered for 10 minutes, and changes in each index were observed for 30 minutes after the start of administration.

Results : The MBR increased in the retinal vessels and choroid area in a dose-dependent manner with the adrenaline load. The Δ mean blood pressure showed a significant correlation (R = 0.37 to 0.77) with each area of ΔMBR.
The Δ carotid blood flow volume showed a significant negative correlation with Δ retinal blood vessel MBR at 100-300 ng/kg dose and the Δ femoral arterial blood flow volume showed a significant positive correlation with Δ choroid area of MBR at each dose.

Conclusions : We successfully demonstraited a real-time evaluation system for systemic-ocular microcirculation using LSFG in white rabbits.
A systemic adrenaline load caused an increase in MBR, associated with elevation in blood pressure.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.