Abstract
Purpose :
Adenosine triphosphate (ATP) is a vasoactive compound assumed to be involved in the pathophysiology of retinal vascular disease such as diabetic retinopathy. ATP has been shown to induce both vasoconstriction and vasodilatation, but it is unknown to what extent these effects depend on the diameter of the vessels, the route of administration of the compound, or on degradation products of ATP. Therefore, the purpose of the present study was to investigate the diameter response of ATP on the arterioles, precapillary arterioles and capillaries during intra- and extravascular application of the compound.
Methods :
Porcine superior hemiretinas (n=16) were mounted in a specially designed tissue chamber allowing diameter measurements of arterioles, precapillary arterioles and capillaries during intra- and extravascular application of vasoactive compounds. The diameter responses were studied during intra- and extravascular administration of ATP or the non-degradable ATP analogue ATP-γS.
Results :
Intravascular administration of ATP induced significant constriction (p<0.01) and extravascular administration significant relaxation (p<0.05) of retinal vessels at all three branching levels. The effects of ATP-γS were similar, except for a lack of contraction of arterioles and capillaries (p>0.29), and a lack of dilatation of precapillary arterioles and capillaries (p>0.30).
Conclusions :
ATP can induce contraction after intravascular application and dilatation after extravascular application on porcine retinal vessels ex vivo. The effects depend on the branching level of the vessels and are due to both ATP and ATP degradation products. The effects of purine agonists and antagonists on retinal vessel diameters ex vivo can be assumed to depend on the route of administration of the compounds and the vascular branching level which is targeted.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.