Pulmonary hypertension alters blood flow distribution and impairs the hyperemic response in the rat diaphragm.

Autor:	Schulze KM; Department of Kinesiology, Kansas State University, Manhattan, KS, United States., Horn AG; Department of Kinesiology, Kansas State University, Manhattan, KS, United States., Weber RE; Department of Kinesiology, Kansas State University, Manhattan, KS, United States., Behnke BJ; Department of Kinesiology, Kansas State University, Manhattan, KS, United States., Poole DC; Department of Kinesiology, Kansas State University, Manhattan, KS, United States.; Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, United States., Musch TI; Department of Kinesiology, Kansas State University, Manhattan, KS, United States.; Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, United States.
Jazyk:	angličtina
Zdroj:	Frontiers in physiology [Front Physiol] 2023 Dec 22; Vol. 14, pp. 1281715. Date of Electronic Publication: 2023 Dec 22 (Print Publication: 2023).
DOI:	10.3389/fphys.2023.1281715
Abstrakt:	Pulmonary hypertension (PH) is characterized by pulmonary vascular remodeling, respiratory muscle and cardiac impairments, and exercise intolerance. Specifically, impaired gas exchange increases work of the diaphragm; however, compromised contractile function precludes the diaphragm from meeting the increased metabolic demand of chronic hyperventilation in PH. Given that muscle contractile function is in part, dependent upon adequate blood flow ( Q ˙ ), diaphragmatic dysfunction may be predicated by an inability to match oxygen delivery with oxygen demand. We hypothesized that PH rats would demonstrate a decreased hyperemic response to contractions compared to healthy controls. Methods: Sprague-Dawley rats were randomized into healthy (HC, n = 7) or PH (n = 7) groups. PH rats were administered monocrotaline (MCT) while HC rats received vehicle. Disease progression was monitored via echocardiography. Regional and total diaphragm blood flow and vascular conductance at baseline and during 3 min of electrically-stimulated contractions were determined using fluorescent microspheres. Results: PH rats displayed morphometric and echocardiographic criteria for disease (i.e., acceleration time/ejection time, right ventricular hypertrophy). In all rats, total costal diaphragm Q ˙ increased during contractions and did not differ between groups. In HC rats, there was a greater increase in medial costal Q ˙ compared to PH rats (55% ± 3% vs. 44% ± 4%, p < 0.05), who demonstrated a redistribution of Q ˙ to the ventral costal region. Conclusion: These findings support a redistribution of regional diaphragm perfusion and an impaired medial costal hyperemic response in PH, suggesting that PH alters diaphragm vascular function and oxygen delivery, providing a potential mechanism for PH-induced diaphragm contractile dysfunction. Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. (Copyright © 2023 Schulze, Horn, Weber, Behnke, Poole and Musch.)
Databáze:	MEDLINE
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