• Modeling Mechanism：

  Trimethylamine N-oxide dihydrate (TMAO・2H₂O, active ingredient TMAO) induces acute myocardial function changes through the following mechanisms: ① Directly enhances the opening probability of L-type calcium channels in cardiomyocytes, promotes calcium influx and calcium-induced calcium release, and increases intracellular calcium concentration (Fluo-4 fluorescence intensity increases by 2.2-2.7 times); ② Activates calmodulin-dependent protein kinase II (CaMKII), phosphorylates sarcoplasmic reticulum calcium ATPase (SERCA) to inhibit protein phosphoproteins, accelerates calcium reuptake, and simultaneously increases myocardial contraction and relaxation rates; ③ Simulates the pathological state of TMAO accumulation in chronic kidney disease (CKD), inducing positive inotropic and chronotropic effects in the myocardium, providing a model for studying the acute pathological process of uremic cardiomyopathy.

• Related Products：

  Trimethylamine N-oxide dihydrate (T5247)

• Modeling Method：

  Experimental Subject：

  Mice, CD-1 strain, male, 12 weeks old, body weight 25–30 g

  Dosage and Administration Route：

  ① Core modelling (isolated heart method):
  - Langendorff perfusion system: Retrograde aortic perfusion, Trimethylamine N-oxide, Final concentration 30–300 μM, Dissolved in oxygenated Ringer's solution (pH 7.4), Assay performed after 20 minutes of perfusion;
  - Organ bath method: Isolated mouse ventricular muscle strips suspended in Ringer's solution containing 95% O₂+5% CO₂, supplemented with Trimethylamine N-oxide (300 μM, 3 mM); contractile function assessed via electrical stimulation (1 Hz, 5 ms, 40 V) after 30 minutes;
  ② Control treatment: Control group administered equal volume of TMAO-free Ringer's solution; additional mannitol (300 μM, 3 mM) osmotic control established;

  Dosing Frequency and Duration Model：

  Single dose

• Validation：

  1. Functional Indicators: - Myocardial contractility: Isometric tension of mouse myocardial strips increased by 20%-41%, and tension of human myocardial tissue increased by 29% (p<0.05); - Contraction/relaxation rate: Maximum slope increased by 22%-55%, and minimum slope increased by 27%-43% (p<0.05); - Intracellular calcium concentration: Fluo-4 AM fluorescence intensity under multiphoton microscopy increased by 2.2 times (300 μM) and 2.7 times (3 mM) compared with the control group (p<0.05); 2. Molecular Indicators: - Calcium signaling pathway: Increased CaMKII phosphorylation level and enhanced SERCA activity (Western blot detection); 3. Specificity Validation: - TMAO precursor TMA (3-300 μM) showed no contractile enhancement effect, excluding precursor interference; - Mannitol control group showed no functional changes, excluding osmotic pressure influence.

*Precautions： Mice were anesthetized by inhalation of 3% isoflurane. After rapid heart harvesting, the mice were placed in 4°C ice-cold Ringer's solution to avoid myocardial ischemia and injury.

*References：Oakley CI,et,al. Trimethylamine-N-oxide acutely increases cardiac muscle contractility. Am J Physiol Heart Circ Physiol. 2020 May 1;318(5):H1272-H1282.