[Dilatation of arterioles in the frog submaxillary muscle under the influence of visible light].

Frog denervated submaxillar muscle arterioles dilates under the influence of visible light. In darkness the vessel returns to tis initial condition. The degree of dilatation is in the main inversely proportional to the initial diameter of the vessel. Besides, the vessel reactivity also depends on the thickness of its wall. Thick-walled arterioles are the most reactive ones. Their diameter becomes 2 -3 times greater under the influence of visible light. This light-evoked vasodilatation should be taken into account during intravital microscopy, as such a considerable dilatation of arterioles caused by light changes their reactivity considerably.