Contractile Smooth Muscle Regulates Dural Venous Sinus Diameter

The brain’s extensive energy demands are supported by a complex vascular network that ensures continuous blood supply and drainage. Ultimately, all cerebral blood is drained back to the heart through the dural venous sinus network. Although these large veins have been presumed to function as passive, low-pressure conduits to facilitate outflow, their ability to constrict and dilate and potentially regulate blood flow has not been explored in detail. Here, using mouse models, we characterized the mRNA expression of dura mater mural cells using single-cell RNA sequencing and investigated vascular zone-specific smooth muscle cell (SMC) protein expression using immunohistochemistry. Further, we observed contractile responses in the superior sagittal sinus (SSS) under various stimuli, including vasoconstrictor and vasodilator compounds, using a pressurized ex vivo live dura mater preparation and an in vivo cranial window approach. Lastly, using myh11-GCaMP6f mice, we investigated sinus SMC Ca 2 + signaling, including baseline signaling and responses to pressure, vasoconstrictors, and nerve stimulation using electrical field stimulation (EFS). Single-cell mRNA analysis revealed a unique population of mural cells expressing both arterial and venous SMC-specific genes. Immunohistochemistry demonstrated that the dural venous sinuses are the only dural veins with SMCs expressing canonical contractile proteins. The SSS constricted in response to pressures from 1–20 mmHg, with peak constriction at 5 mmHg. Vasoconstrictor and vasodilator compounds induced significant constriction and dilation of the SSS both ex vivo and in vivo, while bridging veins remained unaffected. Exogenous phenylephrine administration to the sinus cranial window in vivo caused constriction of the sinus without altering underlying pial vessels. Baseline Ca2+ events were seen both in vivo and ex vivo and contractile agonists elevated cytosolic Ca 2 + in SSS SMCs. EFS induced Ca2+ events and vasoconstriction ex vivo. These findings reveal that the dural venous sinuses possess intrinsic contractile properties, suggesting an active role in regulating cerebral venous outflow. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.