Nitric oxide, KATP channels and endothelin-1 modulate brain pericyte function, vascular tone and neurovascular coupling

Neurotransmitter-mediated signaling correlates strongly to changes in cerebral blood flow (CBF), and functional neuroimaging relies on the robust coupling between activity and CBF, i.e. neurovascular coupling (NVC). We here reveal that key endothelial signaling molecules, nitric oxide (eNO) and endothelin-1 (ET1), modulate pericyte contractility and that pericyte ATP-sensitive potassium (KATP) channels interact with endothelial factors to modulate vascular tone and NVC. We show that NVC requires local synthesis of cGMP, but not NO derived from endothelial cells. The potent endothelial vasoconstrictor ET1 contracted pericytes by IP3 receptor mediated Ca2+ release and blocked NVC. In comparison, pericyte KATP channel openers increased the diameter of capillaries by deactivation of L-type Ca2+ channels while KATP blockers shortened the NVC response. All vasoactive stimuli produced the largest diameter changes at the first capillary that branches off from the penetrating arteriole. Our results reveal that three different signaling pathways mediate the effects of NO, ET1 and KATP channels on brain pericytes and capillary blood flow by mechanisms similar to vascular smooth muscle despite great differences in morphology.