Advanced glycation endproduct modified basement membraneattenuates endothelin-1 induced [Ca2+]i signalling andcontraction in retinal microvascular pericytes

[摘要] Purpose: To assess the effects of advanced glycation endproduct(AGE) modification of vascular basement membrane (BM) on endothelin-1(Et-1) induced intracellular [Ca2+] ([Ca2+]i)homeostasis and contraction in retinal microvascular pericytes (RMP).Methods: RMPs were isolated from bovine retinal capillaries andpropagated on AGE modified BM extract (AGE-BM) or non-modified nativeBM. Cytosolic Ca2+ was estimated using fura-2 microfluorimetry andcellular contraction determined by measurement of planimetric cellsurface area. ETA receptor mRNA and protein expression wasassessed by real time RT-PCR and western blotting, respectively.Results: Exogenous endothelin-1 (Et-1) evoked rises in[Ca2+]i and contraction in RMPs were found to be mediatedentirely through ETA receptor (ETAR) activation. Both peakand plateau phases of the Et-1 induced [Ca2+]i response andcontraction were impaired in RMPs propagated on AGE modified BM.ETAR mRNA expression remained unchanged in RMPs exposed to nativeor AGE-BM, but protein expression for ETAR (66 kDa) was lower inthe AGE exposed cells.Conclusions: These results suggest that substrate derived AGEcrosslinks can influence RMP physiology by mechanisms which includedisruption of ETA receptor signalling. AGE modification ofvascular BMs may contribute to the retinal hemodynamic abnormalitiesobserved during diabetes.

[学科分类] 生物化学/生物物理