Nitric oxide-sensitive and -insensitive contractions of the isolated rabbit iris sphincter muscle.

Abstract

This study showed that SNP inhibited cholinergic contractions mainly through a cyclic GMP-dependent mechanism but did not affect the tachykinergic contractions, indicating that cholinergic contraction is NO sensitive, whereas tachykinergic contraction is NO insensitive. These findings suggest that in rabbits, the cholinergic and tachykinergic responses have distinct features for the fine adjustment of the iris sphincter muscle tone.