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 bronchoc onstriction was compared in spontaneously breathing, halothane-anesthe tized Wistar rats. The inhalation of acetylcholine induced significant alterations of the spontaneous breathing parameters evaluated by whol e-body plethysmography without significant differences between the tre atment groups. Forced parameters detect airflow changes with a greater sensitivity and were measured in hyperventilation-induced temporary a pnoea after the challenge. The forced expiratory volume in 0.1 s revea led a significant protective effect of 11.4 pmol/kg/min urodilatin com pared to the controls whereas the parameters of the forced expiratory flow-volume curve were significantly preserved by 11.4 and 22.8 pmol/k g/min urodilatin (P < 0.05). Urodilatin showed protective effects agai nst an acetylcholine challenge whereas CDD/ANP-(99-126) was without si gnificant influence.