Related Experiment Video
Updated: Aug 19, 2026
Hemodynamic Characterization of Rodent Models of Pulmonary Arterial Hypertension
Published on: April 11, 2016
Hypoxemia and elevated tachykinins in rat monocrotaline pneumotoxicity
Y L Lai1, A A Thacker, J N Diana
1Pharmacology and Experimental Therapeutic Division, College of Pharmacy, University of Kentucky, Lexington 40536, USA.
Abstract:
This study was performed to test whether monocrotaline (MCT)-induced early airway dysfunction and gas exchange abnormalities result in arterial hypoxemia. Thirty young male Sprague-Dawley rats were divided into four groups: control, MCT1, MCT2, and MCT3. Each of the control animals was injected (subcutaneously) with saline; each of the MCT rats was injected with MCT (60 mg/kg, subcutaneously). The rats were tested 1 (MCT1), 2 (MCT2), or 3 (MCT3) weeks after MCT injection. Two days before each animal was tested, it was anesthetized with sodium pentobarbital, and its carotid artery was chronically cannulated. Blood was sampled from the arterial catheter of the conscious rat, and blood gases and pH were measured. Pulmonary arterial pressure (Ppa) was determined in the anesthetized, open chest animal. Heart weight was measured and a weight ratio obtained of right ventricle (RV) to left ventricle plus septum (LV+S). The amount of lung substance P and airway neutral endopeptidase (NEP) activity were also measured. MCT significantly decreased arterial oxygen tension (Pao2) and increased the RV/(LV+S) weight ratio 2 and 3 weeks after administration, whereas it did not significantly increase Ppa until 3 weeks after injection. MCT significantly increased lung substance P levels and decreased airway NEP activities 1-3 weeks after administration. These data suggest that tachykinins cause hypoxemia and RV hypertrophy; then hypoxia may augment the development of pulmonary hypertension.
Insights
Monocrotaline exposure caused early arterial hypoxemia and airway dysfunction in rats. These changes may lead to pulmonary hypertension and right ventricular hypertrophy.
Area of Science:
- Pulmonary Medicine
- Toxicology
- Physiology
Background:
- Monocrotaline (MCT) is a pyrrolizidine alkaloid known to induce pulmonary hypertension.
- Early detection of airway dysfunction and gas exchange abnormalities is crucial for understanding MCT toxicity.
Purpose of the Study:
- To investigate if MCT-induced early airway dysfunction and gas exchange abnormalities lead to arterial hypoxemia.
- To assess the temporal relationship between MCT administration and physiological changes.
Main Methods:
- Male Sprague-Dawley rats were injected with MCT (60 mg/kg) or saline (control).
- Physiological parameters including arterial blood gases (Pao2), pulmonary arterial pressure (Ppa), and right ventricle (RV) to left ventricle plus septum (LV+S) weight ratio were measured at 1, 2, and 3 weeks post-injection.
- Lung substance P levels and airway neutral endopeptidase (NEP) activity were also quantified.
Main Results:
- MCT significantly decreased Pao2 and increased the RV/(LV+S) ratio at 2 and 3 weeks.
- Pulmonary arterial pressure (Ppa) significantly increased only at 3 weeks post-MCT.
- Lung substance P levels increased, and airway NEP activity decreased from 1 to 3 weeks after MCT administration.
Conclusions:
- MCT induces early hypoxemia and airway dysfunction, potentially mediated by tachykinins.
- Hypoxemia may contribute to the development of pulmonary hypertension and right ventricular hypertrophy observed later.
- These findings highlight the complex pathophysiology of MCT-induced lung injury.
