Effect of inhibition of cyclooxygenase on pre- and postjunctional actions of peroxides in the iris-ciliary body

In the present study, we investigated the effect of inhibition of cyclooxyg enase (COX) with flurbiprofen (FBF) on peroxide-induced enhancement of fiel d-stimulated [H-3]norepinephrine ([H-3]NE) release from bovine isolated iri des. Furthermore, the effect of FBF was examined on peroxide-induced attenu ation of contractions evoked by carbachol on this tissue. Irides were prepa red for studies of neurotransmitter release and for measurement of contract ile tension in vitro. Pretreatment of tissues with FBF (10 mu M) caused sig nificant (P < 0.001) rightward shifts of concentration-response curves to H 2O2 and also decreased cumene hydroperoxide (cuOOH)-induced enhancement of evoked [H-3]NE release. FBF (10 mu M) partially prevented the attenuation o f carbachol-induced contractions induced by H2O2 (300 mu M) and cuOOH (300 mu M). We conclude that inhibition of the biosynthesis of prostanoids reduc ed both the prejunctional stimulatory effects of H2O2 and cuOOH on sympathe tic neurotransmission and inhibitory effects of peroxides on carbachol-indu ced contractions the in the bovine isolated iris.