Purchase this article with an account.
Jingsheng Xia, Jason C. Lim, Wennan Lu, Jonathan M. Beckel, Alan M. Laties, Claire H. Mitchell; Mechanosensitive Channels In Isolated Rat Retina Ganglion Cells: Response To Strain From Within Neurons. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6603.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Mechnosensitive channels have been implicated in many physiological functions including regulation of cell volume, blood pressure and pain sensing. We have previously shown that stretching and swelling trigger a release of ATP from isolated retinal ganglion cells (RGCs), and that swelling activates non- specific cation currents in the cells. To explore these currents and eliminate complications associated with hypotonic challenge, here we examine the mechanosensitive currents in retinal ganglion cells exposed to changes in pressure.
RGCs in mixed cultured retinal cells from neonatal rat retina were labeled by injection of fluorescent dye into the superior colliculus. Ionic currents were recorded using both the whole-cell configuration and inside-out single channel mode. Whole-cell recordings were obtained from -100 mV to +80mV using near-physiological solutions. Single channel activity was recorded from inside out patches held from -60 to +40 mV using symmetrical KCl based solutions. Pressure was applied through the patch pipette by the HSPC-1 pressure clamp in both whole-cell and single channel recording.
Application of pressure during whole cell recordings usually led to a distinct increase in current. Current rose with the magnitude of applied pressure; current was increased by 50 ±16 % at -10mmHg, 75 ± 28% at -20 mmHg, 220 ± 75 at -30 mmHg, and 237 ± 108 % at -50 mmHg. Current displayed some inactivation at depolarized potentials, and was basically Ohmic with mild outward rectification. Currents reversed at -61 mV, suggesting a potassium-dominant permeability. Positive pressure also caused an increase in currents although the recordings were not as reliable. In preliminary single channel recordings, two channels were observed with conductances of ~ 140 pS and ~30 pS, although the larger conductance channel was observed more frequently. Application of positive pressure of 10-50 mmHg increased the open times of both channel types.
RGCs possess mechanosensitive channels and respond directly to changes in pressure. The channels are predominantly permeable to potassium. The molecular identity of these channels, and their potential role in the pathogenesis of glaucoma, awaits further investigation.
This PDF is available to Subscribers Only