Enriched Expression of TRPV4 Channels in Myoendothelial Projections of Rat Posterior Cerebral and Superior Cerebellar Arteries

Our laboratory recently reported that activation of the ankyrin (A) Transient Receptor Potential (TRP) channel TRPA1 mediates endothelium‐dependent vasodilation and that expression of the channel is enriched in projections of the endothelial cell plasma membrane that penetrate the internal elastic lamina proximal to smooth muscle cells. These projections are also the sights of dynamic Ca 2+ events that hyperpolarize the endothelial cell plasma membrane. Activation of the vanilloid (V) TRP channel TRPV4 causes arterial dilatation that is partially endothelium dependent. We hypothesized that TRPV4 is also localized in the myoendothelial projections of endothelial cells in rat cerebral arteries. To test this hypothesis, rat posterior and middle cerebral and superior cerebellar arteries were cut longitudinally and pinned to silgard blocks with the endothelium facing up. Arteries were fixed, immunostained with TRPV4‐specific antibodies, and imaged using confocal microscopy. We find that TRPV4 expression is present in the endothelium of posterior cerebral and superior cerebellar arteries and is enriched in myoendothelial projections, but was not detected in the endothelium of middle cerebral arteries. Segmental expression of TRPV4 in the cerebral vasculature suggests a complex role for the channel in the regulation of cerebral blood flow. R01HL091905 (SE); F31HL094145 (ALG)