Effects of near-infrared low-level laser irradiation on microcirculation

Lasers Surg Med. 2000;27(5):427-37. doi: 10.1002/1096-9101(2000)27:5<427::AID-LSM1004>3.0.CO;2-A.


Background and objective: Recently, there has been an increase in the clinical application of low-level laser irradiation (LLLI) in various fields. The present study was conducted to explore the effects of LLLI on microcirculation.

Study design/material and methods: We investigated the effects of LLLI on rat mesenteric microcirculation in vivo, and on cytosolic calcium concentration ([Ca2+]i) in rat vascular smooth muscle cells (VSMCs) in vitro.

Results: LLLI caused potent dilation in the laser-irradiated arteriole, which led to marked increases in the arteriolar blood flow. The changes were partly attenuated in the initial phase by the superfusion of 15 microM L-NAME, but they were not affected by local denervation. Furthermore, LLLI caused a power-dependent decrease in [Ca2+]i in VSMCs.

Conclusion: The circulatory changes observed seemed to be mediated largely by LLLI-induced reduction of [Ca2+]i in VSMCs, in addition to the involvement of NO in the initial phase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Arterioles / innervation
  • Arterioles / physiology
  • Arterioles / radiation effects
  • Blood Flow Velocity / radiation effects
  • Calcium / metabolism
  • Denervation
  • Enzyme Inhibitors / pharmacology
  • In Vitro Techniques
  • Lasers*
  • Male
  • Mesentery / blood supply*
  • Microcirculation / radiation effects
  • Muscle, Smooth, Vascular / metabolism
  • Muscle, Smooth, Vascular / radiation effects
  • NG-Nitroarginine Methyl Ester / pharmacology
  • Nitric Oxide Synthase / antagonists & inhibitors
  • Radiation Dosage
  • Rats
  • Rats, Wistar
  • Vasodilation / radiation effects


  • Enzyme Inhibitors
  • Nitric Oxide Synthase
  • Calcium
  • NG-Nitroarginine Methyl Ester