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. Author manuscript; available in PMC: 2008 Apr 3.
Published in final edited form as: Exp Physiol. 2007 Apr 13;92(4):635–640. doi: 10.1113/expphysiol.2006.036376

Figure 1. Light stimulation, but not glial cell depolarization, evokes vasodilatation.

Figure 1

A and B, micrographs showing a whole cell-patched astrocyte contacting an arteriole. The patch pipette is seen at the left. A, infrared-differential interference contrast (IR-DIC) image. B, fluorescence image showing the Lucifer Yellow-filled astrocyte contacting the arteriole. Additional astrocytes coupled to the patched cell are also seen. Scale bar for A and B represents 10 μm. C, time course of vessel diameter change. Flickering light stimulation evokes vasodilatation, demonstrating neurovascular coupling in the retina. D, the astrocyte shown in A and B is depolarized by injection of 1 nA current. Arteriole diameter does not change during the depolarization, indicating that K+ siphoning is not sufficient to initiate vasodilatation. In a series of experiments, glial cells were depolarized to membrane potentials ranging from −40 to +120 mV, sufficient to produce K+ siphoning in many glial cells coupled together. Each cell was depolarized multiple times. No change in arteriole diameter was observed during glial depolarization.