Effect of mode of application of papaverine on the contractile response of the internal mammary artery

A study was performed to investigate the duration of action of papaverine applied either intraluminally or in a combined intraluminal and extraluminal fashion in vitro, and how the reactivity of the internal mammary artery (IMA) to a range of vasoconstrictors is affected. Segments of IMA exposed to only intraluminal papaverine (10−4 mol/1) for 15 min recovered their contractile response to 90 mmol/1 potassium chloride to pretreatment levels within 2h. In contrast, combined intraluminal and extraluminal administration of papaverine resulted in a significant depression of the contractile response to 90 mmol/1 potassium chloride (P