CARDIOVASCULAR ACTIONS OF THE FUROXAN CAS-1609, A NOVEL NITRIC-OXIDE DONOR

1 This study examines the cardiovascular effects of CAS 1609 (4-hydrox ymethyl-furoxan-3-carboxamide) in vitro as well as in vivo in various animal models. 2 CAS 1609 relaxed guinea-pig pulmonary artery strips w ithout endothelium with IC50-values of 0.9 mu M (phenylephrine contrac ted) and 15 mu M (KCl-depolarized). This effect was inhibited by oxyha emoglobin. In these arteries CAS 1609 significantly increased (+192%) guanosine 3':5'-cyclic monophosphate levels, which indicates that the compound acts as a donor of nitric oxide (NO). 3 In the anaesthetized pig, CAS 1609 (0.3-1.0 mg kg(-1), i.d.) significantly lowered blood pr essure and left ventricular end-diastolic pressure. Left ventricular c ontractility was slightly reduced and heart rate remained almost uncha nged. 4 In anaesthetized dogs, i.v. or i.d. administration of CAS 1609 (0.3-3.0 mg kg(-1)) decreased, in a dose-related fashion, preload and afterload of the heart, cardiac output, left ventricular work and myo cardial oxygen consumption. This haemodynamic profile is similar to th at of known NO-donors. 5 In anaesthetized dogs with acute heart failur e due to intracoronary injection of microspheres, CAS 1609 (0.3 mg kg( -1), i.v.) improved the haemodynamic condition and reduced mortality b y 80%. 6 In conscious dogs, oral treatment with a dose of 0.5 mg kg(-1 ) given twice daily at 07 h 00 min and 19 h 00 min (each dose had a du ration of action greater than or equal to 12 h) for 5 days showed no s igns of tolerance to the haemodynamic effects of the drug. 7 All these data indicate that CAS 1609 is a potent, long-lasting orally active d onor of NO, devoid of tolerance development.