Abstract
Abstract: :
Purpose: There have been a number of reports in other organs indicating that the administration of contrast media for angiographic studies can induce changes in vessel tone. The aim of our study was to determine whether clinically relevant doses of sodium fluorescein could produce changes in vascular tone in retinal arterioles and veins. Methods: Segments of porcine retinal arterioles and veins were dissected, cannulated, and perfused, and their outer diameter monitored during intraluminal application of increasing doses (10-9- 10-3 %) of sodium fluorescein. A control injection (perfusate only) was performed prior to sodium fluorescein application and endothelin-1 (10-9 M) was used to assess the vasoactive response of the vessels after sodium fluorescein administration. The significance of any induced change in vessel diameter was assessed in relation to the initial vessel diameter. Results: Sodium fluorescein produced a significant dose dependent contraction in porcine retinal arterioles and veins with a threshold of 10-8 – 10-7 % sodium fluorescein. At the maximal dose tested (10-3 %) vessel diameter was reduced to ~85% of the initial vessel diameter in retinal arteries and veins. After sodium fluorescein exposure normal vasoactive responses to endothelin-1 were maintained. Conclusions: Sodium fluorescein can potentially induce vasoconstrictive effects on the retinal vasculature. Although sodium fluorescein is believed to be a relatively safe agent for use in routine clinical diagnosis, the mechanisms of the observed vasoconstrictive effects of sodium fluorescein require further investigation.