Loop diuretics like furosemide are commonly used in heart failure (HF) treatment, but their effects on disease progression are still unclear. Furosemide treatment accelerates HF deterioration in a swine model, but the mechanism of acceleration is poorly understood. We hypothesized that furosemide activates inflammatory signaling in the failing left ventricular (LV) myocardium, leading to adverse remodeling of the extracellular matrix (ECM). A total of 14 Yorkshire pigs underwent permanent transvenous pacemaker implantation and were paced at 200 beats per minute; 9 non-instrumented pigs provided controls. Seven paced animals received normal saline, and seven received furosemide at a dose of 1 mg/kg intramuscularly. Weekly echocardiograms were performed. Furosemide-treated animals reached the HF endpoint a mean of 3.2 days sooner than saline-treated controls (mean 28.9 ± 3.8 SEM for furosemide and 32.1 ± 2.5 SEM for saline). The inflammatory signaling protein transforming growth factor-beta (TGF-β) and its downstream proteins were significantly (p ≤ 0.05) elevated in the LV after furosemide treatment. The regulatory factors in cell proliferation, mitogen-activated protein kinase signaling pathway proteins, and matrix metalloproteinases were elevated in the furosemide-treated animals (p ≤ 0.05). Our data showed that furosemide treatment increased ECM remodeling and myocardial fibrosis, reflecting increased TGF-β signaling factors, supporting prior results showing worsened HF.

Background/Objective: Exertional rhabdomyolysis (ER) is primarily driven by mechanical stress on muscles during strenuous or unaccustomed exercise, often exacerbated by environmental factors like heat and dehydration. While the general cellular pathway involving energy depletion and calcium overload is understood in horse ER models, the underlying mechanisms specific to the ER are not universally known within humans. This study aimed to evaluate whether patients with ER exhibited transcriptional signatures that were significantly different from those of healthy individuals. Methods: This study utilized RNA sequencing on skeletal muscle samples from 19 human patients with ER history, collected at a minimum of six months after the most recent ER event, and eight healthy controls to investigate the transcriptomic landscape of ER. To identify any alterations in biological processes between the case and control groups, functional pathway analyses were conducted. Results: Functional pathway enrichment analyses of differentially expressed genes revealed strong suppression of mitochondrial function. This suppression included the “aerobic electron transport chain” and “oxidative phosphorylation” pathways, indicating impaired energy production. Conversely, there was an upregulation of genes associated with adhesion and extracellular matrix-related pathways, indicating active restoration of muscle function in ER cases. Conclusions: The study demonstrated that muscle tissue exhibited signs of suppressed mitochondrial function and increased extracellular matrix development. Both of these facilitate muscle recovery within several months after an ER episode.