Induced Spasm in the Retinal Arterioles of Cats

Abstract

In the present study we have observed the reactivity of retinal arterioles which were surgically exposed and directly stimulated, a method successfully used in studying spasm of cerebral arteries.¹ A controversy concerning the nature of transient narrowing of retinal arterioles has existed since the invention of the ophthalmoscope. The observation that certain abnormally narrow retinal arterioles appear on later examination to be of normal caliber is the basis for much speculation about "retinal arterial spasm," a subject recently reviewed by Wagener.² Although the use of the word "spasm" appears to be objectionable to many who will accept the term "narrowing" or even "vasoconstriction," there seems to be little reason not to apply the term "spasm" to a local and transient narrowing of arterioles. This narrowing, as our results show, immediately follows mechanical stimulation of an arteriole and presumably results from contraction of the smooth muscle in the arteriolar