Type A natriuretic peptides exhibit different bronchoprotective effects in rats

The protective effect of 11.4, 22.8 or 45.6 pmol/kg/min cardiodilatin/atrial natriuretic peptide (CDD/ANP-(99-126)), urodilatin (CDD/ANP-(95-126)) or vehicle intravenously against acetylcholine-induced bronchoconstriction was compared in spontaneously breathing, halothane-anesthetized Wistar rats. The inhalation of acetylcholine induced significant alterations of the spontaneous breathing parameters evaluated by whole-body plethysmography without significant differences between the treatment groups. Forced parameters detect airflow changes with a greater sensitivity and were measured in hyperventilation-induced temporary apnoea after the challenge. The forced expiratory volume in 0.1 s revealed a significant protective effect of 11.4 pmol/kg/min urodilatin compared to the controls whereas the parameters of the forced expiratory flow-volume curve were significantly preserved by 11.4 and 22.8 pmol/kg/min urodilatin (P < 0.05). Urodilatin showed protective effects against an acetylcholine challenge whereas CDD/ANP-(99-126) was without significant influence.