The Effect of Low-dose Papaverine on In-vivo Rabbit Basilar Artery

Kang, Sung Don; Kim, Jong Mun

Abstract

Papaverine has been widely used to reverse cerebral vasospasm because of its vasodilatory effect. However, its therapeutic value has been limited at least in part. In a previous study, low concentration papaverine was observed to potentiate a phorbol dibutyrate induced constriction of rat cerebral microvessels in vitro. The purpose of this study was to investigate the above effect in large cerebral arteries. Rabbit basilar artery was constricted in vivo by topical application of phorbol dibutyrate. The basilar artery was visualized using transclival exposure, and its diameter monitored using videomicroscopy. At the concentrations of 50, 100, and 500 M, papaverine elicits a dose-dependent vasodilatation of basilar artery that had been preconstricted with 20 nM phorbol dibutyrate. Subsequently, the above procedure was repeated, using lower concentrations of papaverine at 0.1, 1 and 10 M with no observable consistent potentiation effect. These results suggest that structural and pharmacological differences between large cerebral arteries and cerebral microvessels may contribute to the differences in their vasospastic response.