APStracts 3:0289H, 1996.

Continuous low dose nitric oxide inhalation does not prevent monocrotaline-induced pulmonary hypertensive changes in rats. Maruyama, Junko, Kazuo Maruyama, Yoshihide Mitani, Masayoshi Kitabatake, Toru Yamauchi, Katsuyuki Miyasaka. Departments of Anesthesiology, Physiology, Pediatrics, and Public Health, Mie University School of Medicine, and the Department of Emergency Medicine and the Intensive Care Unit, Mie University Hospital, Tsu, Mie, and Pathophysiology Research Laboratory, National Children's Medical Research Center, Setagaya, Tokyo, Japan

APStracts 3:0289H, 1996.

We determined if vasodilator doses of inhaled nitric oxide (NO) prevented the progression of pulmonary hypertension (PH) and vascular changes in monocrotaline-induced PH. Short-term NO inhalation in the rats 3 weeks after the injection of monocrotaline reduced mean pulmonary artery pressure (mPAP) from 30.7+/-2.2(SE) to 26.4+/-1.4 mmHg at 10 ppm, and from 30.2+/-1.3 to 25.8+/-1.4 mmHg at 40 ppm. There were no difference, between rats exposed to air only and rats exposed to 10 ppm NO for 19 days after a single subcutaneous injection of monocrotaline, in mPAP(air 34.3+/-1.9 vs. NO 32.8+/-1.4 mmHg), right ventricular hypertrophy (RVH), medial wall thickness of muscular arteries (MWT), and the percentage of muscularized arteries at alveolar wall (%AW) and duct (%AD) level. Additional groups exposed to air only and 40 ppm NO for 19 days again showed no difference in mPAP, RVH, MWT, and %AD, except that this dose slightly reduced %AW (air 60.6+/-3.4 vs. NO 46.9+/-5.2%, p=0.04). Urine nitrate (NO3-) level was higher in rats that had inhaled NO. In contrast to chronic hypoxic PH, vasodilator doses of NO inhalation did not prevent the development of pulmonary hypertension in this malignant form of experimental PH.

Received 8 June 1995; accepted in final form 1 July 1996.
APS Manuscript Number H523-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 25 July 1996