Rat pulmonary circulation after chronic hypoxia: hemodynamic and structural features

Abstract

In 55 Sprague-Dawley rats (mean wt, 277 +/- 6.2 g) exposed to hypobaric hypoxia (air at 380 mmHg), and 23 weight-matched controls kept in room air, pulmonary and systemic artery pressures were measured daily for 2 wk via indwelling catheters. After each day of exposure, 1 or 2 hypoxic rats, to a total of 20, and 5 control rats were killed during the experiment. In these rats, the pulmonary arterial tree was injected post mortem with barium-gelatin and inflated with formaldehyde solution, and three structural features were quantified microscopically: 1) abnormal extension of muscle into peripheral arteries where it is not normally present (EMPA); 2) increased wall thickness of the normally muscular arteries, expressed as a percentage of external diameter (%WT); and 3) reduction in artery number expressed as an increase in the ratio of alveoli to arteries (A/a). Mean pulmonary artery pressure (Ppa) rose significantly after day 3 of hypoxic exposure (P less than 0.05) and had doubled by day 14; the mean systemic artery pressure (Psa) of hypoxic rats and Ppa and Psa of control rats were unchanged. The level of Ppa correlated with the degree of structural changes; for EMPA, r = 0.84; for %WT, r = 0.64; and for A/a, r = 0.73 (P less than 0.001 in all.

Reoxygenation Reverses Hypoxic Pulmonary Arterial Remodeling by Inducing Smooth Muscle Cell Apoptosis via Reactive Oxygen Species–Mediated Mitochondrial Dysfunction

“…A soft catheter linked to a pressure transducer was inserted into the right ventricle through the right external jugular vein. Right ventricle systolic pressure (RVSP), approximately equal to pulmonary arterial pressure,31, 32 was recorded on the monitor of the Powerlab system (AD Instruments, Castle Hill, New South Wales, Australia). Systemic systolic pressure was measured through a catheter inserted into the carotid artery.…”

Changes in Pulmonary Hemodynamics during Normoxia and Hypoxia in Awake Rats Treated with Intratracheal Bleomycin.

“…After anesthesia was induced with intraperitoneal sodium pentobarbital (5 mg/100 g body weight), the pulmonary artery was catheterized and the catheter maintained in situ by the modified technique of Rabinovitch et al (1979). Briefly, a small incision was made in the neck and the right jugular vein was isolated.…”

NFATc3 Mediates Chronic Hypoxia-induced Pulmonary Arterial Remodeling with α-Actin Up-regulation

“…Similar levels of hypoxia are present in patients with chronic bronchitis, emphysema, cystic fibrosis, asthma, and severe restrictive lung diseases (1). Chronic hypoxia (CH) 2 causes pulmonary hypertension due to pulmonary vasoconstriction, arterial remodeling, and polycythemia, which ultimately results in right ventricular (RV) hypertrophy and often heart failure (2). Pulmonary vasoconstriction is thought to be caused by elevated vascular tone through increased pulmonary arterial smooth muscle cell (PASMC) intracellular Ca 2ϩ ([Ca 2ϩ ] i ) (3)(4)(5)(6)(7)(8) and increased sensitivity of the contractile apparatus to Ca 2ϩ (9 -12).…”