He-Ne laser radiation influence on single-channel ionic currents through cell membranes: a patch-clamp study

The electrophysiological characteristics rat spinal cord neurons, rat hippocampus pyramidal neurons, guinea pig cardiomyocytes, rat brain glial cells, and bovine pulmonary artery endothelial cells were measured by the common patch- clamp technique. No light effects on the voltage-activated whole-cell ionic currents were found in any type of the cells. The only ionic current type influenced by the radiation in all the cells under study was the background single-channel currents recorded inn the cell-attached configuration. The opening frequency of the background single channels was suppressed by the light and the open state probability was decreased under the irradiation. The same channels in the inside-out patches were found to be light insensitive.