Abstract
Purpose :
Adenosine triphosphate (ATP) is assumed to be involved in the pathophysiology of retinal vascular disease such as diabetic retinopathy. ATP has been shown to induce vasoconstriction after intravascular application and vasodilatation after extravascular application ex vivo, but it is unknown which receptors are involved in the vasoactive effects. 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 in the presence and absence of specific antagonists.
Methods :
Porcine superior hemiretinas (n=32) were mounted in a specially designed tissue chamber, and the diameter of retinal arterioles, precapillary arterioles and capillaries were studied during intra- and extravascular application of vasoactive compounds with and without antagonists to the P2-purinergic receptor (PPADS), the A3-adenosine receptor (MRS 1523) and the synthesis of cyclooxygenase products (ibuprofen).
Results :
After intravascular application of ATP, contraction of arterioles was blocked by both PPADS (p<0.01) and MRS 1523 (p<0.01), contraction of pre-capillary arterioles by PPADS (p=0.03) and contraction of capillaries by MRS 1523 (p=0.01). After extravascular application of ATP, dilatation of arterioles and capillaries were blocked by ibuprofen (p<0.05), whereas the dilatation of pre-capillary arterioles was not blocked by any of the studied antagonists (p>0.09 for all comparisons).
Conclusions :
ATP-induced changes in the diameter of retinal vessels are regulated differentially in larger arterioles, pre-capillary arterioles and capillaries. This may form the basis for selective interventions on the diameter of retinal vessels at different branching levels.
This is a 2020 ARVO Annual Meeting abstract.