Gap junction blockage in chorioallantoic membrane networks

Abstract

BackgroundStudies using theoretical models have revealed the necessity of information transfer along blood vessels, most likely mediated via gap junctions, to achieve efficient blood flow distribution in microvascular networks. Its absence might lead to malperfusion. Here we studied the effects of gap junction blockade on vessel diameter in chick chorioallantoic membrane (CAM) networks by intravital microscopy.MethodsBlockers used were carbenoxolone (175 μM, CBX), palmitoleic acid (100 μM, PA) and GAP27 (1000 μM). Maximal vasodilation (acetylcholine 10 μM, adenosine 100 μM, papaverine 200 μM, sodium nitroprusside 10 μM) allowed examining the relative contribution of changes in vessel structure and vascular tone.ResultsAfter 3h, diameters of arteries and veins decreased to 0.55 and 0.54 (relative to PBS control; CBX), 0.77 and 0.81 (PA) and 0.82 and 0.76 (GAP27). For CBX, about half (59%, 46%) of the diameter reduction was caused by structural adaptation, the rest by an increase in vascular tone. After 6h, diameter reduction was unchanged (0.55 and 0.45) but mainly caused by structural adaptation (96% and 88%).ConclusionThe present findings show the importance of gap junction based communication for developing microvascular networks. Gap junction blockade causes a substantial decrease in vessel diameter with an initial increase in vascular tone and a subsequent change of vessel structure.