[Organ Bath Experiments on Human Pulmonary Vessels: Assessment of Drug Efficacy for Treatment of Pulmonary Arterial Hypertension].

Various vasodilator medications are used in the treatment of pulmonary arterial hypertension (PAH), such as endothelin receptor antagonists (ERA) or phosphodiesterase-5-(PDE-5-)inhibitors. In a human ex vivo model, we investigated whether the combination of two substance classes could achieve a higher effect or - without loss of vasodilatation - a lower dosage of the individual substances might be sufficient. We established an ex vivo organ bath model to evaluate the dose-dependent effects of ERA and PDE-5-inhibitors on pulmonary vessels harvested from patients who underwent surgery (lung resection/transplantation). We compared the combined use of both substance classes with administration of one class of drugs alone. Due to the limitations of the experimental design, it is not possible to extrapolate our results to the conditions in vivo. Nevertheless, organ bath proved to be helpful in evaluating the dose-dependent effects of ERA and PDE-5 inhibitors, which is not practical in everyday clinical practice. In this setting, the effectiveness of the combination therapy and the potential for dose reduction depended on the concentrations used and on the influence of previous illnesses on blood vessel function. This article describes the most important results of our experimental investigations and suggestions for future projects.