Figure 21. Distinct and shared cellular and molecular mechanisms involved in neurovascular coupling defects in sporadic and genetic cSVDs.

During aging (B), there is an increased arterial stiffness and a reduction in arterial SMC coverage crippling arterial dilation. In angiotensin II-dependent hypertension, one mechanism (C) involves an increased production of reactive oxygen species (ROS) by perivascular macrophages (PVM) that reduces the bioavailability of nitric oxide (NO) leading to a reduction in vasodilation. In CADASIL (D), TIMP3 accumulation in the pericyte-endothelial cell basement membranes causes a decrease in ATP-dependent synthesis of PIP2 leading to a reduction in Kir2.1 activity and crippling the endothelial cell (EC) retrograde hyperpolarization. In the COL4A1/2 cSVD (E), NVC is also caused by a reduction in Kir2.1 activity but this arises from a reduced PIP2 availability as a consequence of abnormal basement membranes (dashed grey line below SMCs).