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Mikkel Misfeldt, Toke Bek; Nmda Induced Relaxation Of Porcine Retinal Arterioles In Vitro Is Accompanied By Activity In A Novel Cellular Bouton Structure In The Vascular Wall. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5665.
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© ARVO (1962-2015); The Authors (2016-present)
A recent study has identified a new cellular bouton structure in retinal vascular walls which is activated by ATP to induce vasodilation. However, it is unknown which compounds initiate the release of ATP in order to activate these boutons.
Porcine retinal arterioles with a mean diameter of 150 µm were mounted in a myograph and were placed in a confocal microscope (ZEISS LSM 5 PASCAL). The preparations were loaded with the calcium sensitive fluorophore Oregon Green and pre-contracted with 10-6 M U46619. Subsequently, concentration-response experiments with ATP (10-8 M to 10-4 M), the glutamate agonist NMDA (10-6 M to 10-3 M), and adenosine (10-8 M to 10-4 M) were performed during the recording of retinal vascular tone and fluorescence in perivascular boutons (n=6 for all experimental conditions).
ATP and adenosine induced a similar concentration dependent relaxation of the retinal arterioles (p<0.01). During vasodilation with ATP and NMDA, but not with adenosine, an increased hyperfluorescence (p<0.01) was observed in the perivascular boutons.
Both NMDA and ATP induced vasodilatation of porcine retinal arterioles are mediated through a distinct layer of perivascular boutons located outside the vascular smooth muscle cells. The activity in this novel cellular bouton structure may be a potential target for future pharmacological intervention in retinal vascular disease.
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