5-(N,N-dimethyl)-Amiloride (hydrochloride): Precision NHE1 Inhibitor for Cardiac and Endothelial Research

Executive Summary: 5-(N,N-dimethyl)-Amiloride (hydrochloride) is a crystalline derivative of amiloride and a highly selective Na⁺/H⁺ exchanger (NHE1) inhibitor, with sub-micromolar efficacy in mammalian cells (APExBIO). It displays Ki values of 0.02 μM for NHE1, 0.25 μM for NHE2, and 14 μM for NHE3, with minimal effect on other isoforms. This compound is validated for reducing cardiac contractile dysfunction in ischemia-reperfusion models, modulating sodium balance, and suppressing ouabain-sensitive ATPase activity (Chen et al., 2021). It is intended for in vitro and animal research, not clinical use. APExBIO supplies this reagent under catalog number C3505.

Biological Rationale

The Na⁺/H⁺ exchangers (NHEs) regulate intracellular pH and sodium ion homeostasis by exchanging intracellular H⁺ for extracellular Na⁺ in mammalian cells (Chen et al., 2021). NHE1, the most ubiquitous isoform, is pivotal for cell volume control, cardiac contractility, and endothelial function. Dysregulated NHE1 activity contributes to sodium overload, acidosis, and vascular barrier dysfunction, particularly during ischemia-reperfusion injury and sepsis. Moesin, an endothelial cytoskeletal protein, is implicated in sepsis-induced vascular injury, and NHE1-mediated signaling influences its function and permeability (Chen et al., 2021).

Mechanism of Action of 5-(N,N-dimethyl)-Amiloride (hydrochloride)

5-(N,N-dimethyl)-Amiloride (hydrochloride) (DMA) acts as a competitive inhibitor of NHE1, NHE2, and NHE3, with Ki values of 0.02 μM, 0.25 μM, and 14 μM, respectively (APExBIO product page). It blocks Na⁺ influx and H⁺ efflux, thus modifying intracellular pH and Na⁺ concentrations. DMA displays minimal inhibition of NHE4, NHE5, and NHE7, ensuring selectivity. By inhibiting NHE1, DMA prevents sodium-driven cell swelling and acidosis during ischemic insult. Furthermore, it suppresses ouabain-sensitive ATPase activity and alanine transport in hepatocytes, broadening its impact on cellular ion and metabolic regulation. The compound is stable as a crystalline solid, soluble up to 30 mg/ml in DMSO or DMF, and recommended for storage at -20°C.

Evidence & Benchmarks

• DMA inhibits NHE1 with a Ki of 0.02 μM, NHE2 at 0.25 μM, and NHE3 at 14 μM, achieving high selectivity (APExBIO).
• DMA reduces sodium overload and preserves cardiac contractility after ischemia-reperfusion in animal models (Chen et al., 2021).
• DMA inhibits ouabain-sensitive ATP hydrolysis and Na⁺/K⁺-ATPase activity in rat liver plasma membranes (Chen et al., 2021).
• DMA reduces alanine uptake in hepatocytes, indicating effects on broader metabolic pathways (Chen et al., 2021).
• DMA demonstrates minimal inhibition of NHE4, NHE5, and NHE7, confirming isoform discrimination (APExBIO).

Applications, Limits & Misconceptions

DMA is a research reagent for:

• Modeling ischemia-reperfusion injury and assessing interventions to prevent cardiac contractile dysfunction.
• Investigating Na⁺/H⁺ exchanger signaling in vascular and endothelial injury, including sepsis models.
• Studying sodium-driven metabolic processes and cell volume regulation in vitro.

This article extends "5-(N,N-dimethyl)-Amiloride Hydrochloride: Precision NHE1 ..." by integrating updated quantitative selectivity data and direct links to applications in sepsis and endothelial biomarker research. For detailed troubleshooting and advanced use-cases, see "Applied Use of 5-(N,N-dimethyl)-Amiloride Hydrochloride i...", which complements this dossier with workflow tips.

Common Pitfalls or Misconceptions

• DMA is not a pan-NHE inhibitor: It shows minimal inhibition of NHE4, NHE5, and NHE7, so results cannot be generalized to all Na⁺/H⁺ exchanger isoforms.
• Not for clinical or diagnostic use: DMA is strictly for laboratory research and not approved for human or veterinary medical applications.
• Long-term solution storage is discouraged: DMA solutions are unstable over time and should be prepared fresh before use.
• Cardiac protection models are species- and condition-dependent: Efficacy in rodents may not directly translate to human tissues or other species.
• Does not directly modulate moesin (MSN): While it impacts NHE1-related signaling, DMA does not bind or inhibit MSN itself (Chen et al., 2021).

Workflow Integration & Parameters

• Recommended concentration range: 0.01–10 μM for most cellular assays, depending on isoform selectivity and cell type.
• Solubility: Up to 30 mg/ml in DMSO or DMF. Prepare solutions immediately before use to ensure stability (APExBIO).
• Storage: Store powder at -20°C. Avoid repeated freeze-thaw cycles.
• Controls: Include vehicle and isoform-selective controls to distinguish NHE1-mediated effects.
• Assay readouts: Intracellular pH (via pH-sensitive dyes), sodium influx (radioisotope or fluorescence), and contractile function (in tissue models).

For advanced integration in sepsis or endothelial dysfunction models, see the article "5-(N,N-dimethyl)-Amiloride: Advanced Insights in Na+/H+ Exchanger Inhibition", which provides a broader mechanistic context for vascular research. This dossier updates their mechanistic summary with new selectivity and workflow details.

Conclusion & Outlook

5-(N,N-dimethyl)-Amiloride (hydrochloride) enables highly selective and reproducible inhibition of NHE1-mediated Na⁺/H⁺ exchange, underpinning studies in cardiac protection, pH regulation, and vascular barrier function. Its well-characterized selectivity, stability profile, and established benchmarks render it indispensable for cardiovascular and endothelial research. Ongoing studies are expected to further clarify its translational relevance in ischemia, sepsis, and metabolic disorders. For procurement and protocol details, consult the APExBIO product page (C3505).