Far red/near infrared light induces vasodilation and an increase in activity of large conductance potassium channel currents in murine femoral arterial muscle (677.13)

Abstract

Over 8 million Americans are treated for symptoms related to peripheral artery disease (PAD), such as intermittent claudication, impaired wound healing, and critical limb ischemia. We have shown light irradiation at the far red/near infrared region (670 nm (R/NIR)) can stimulate angiogenesis by increasing NO independent of NOS through release of NO from nitrosyl‐heme stores. We hypothesized R/NIR can stimulate vasodilation through increases in large conductance potassium channel (BKCa) activity. To test vasodilation, facial arteries from C57Bl/6 mice were isolated, pressurized to 60mmHg, and pre‐constricted with U46619 in the dark.The vessels were irradiated with 670 nm light (10mW/cm2) up to 5 min at a time with 10 min dark period between irradiation. Vessel diameter increased up to 17.8% (±3.0, p<0.05) after 5 min of R/NIR exposure. The effect of red light on single channel BKCa current was determined in enzymatically dissociated murine femoral arterial muscle cells, using the patch clamp technique and symmetrical KCl [145mM] recording solution at a patch potential of +60 mV (RT). Exposure of cell attached patches to light ( λ =670 nm, 10 mW/cm2) markedly increased the opening frequency of the large conductance potassium channels (BKCa) single channel current. This effect of light on BKCa single channel current activity could be the underlying mechanism for the vasodilatory action of red light in isolated murine femoral arterial segments. Conclusion: R/NIR exposure acts to stimulate vasodilation, by increasing the opening frequency of BKCa single channel current recorded in cell attached patches of femoral arterial smooth muscle cells.