Is Leucine, a Branched-Chain Amino Acid, an Endogenous Anti-Arrhythmic Factor?

et al. 2004

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Tissue levels of nineteen amino acids and total free amino acids, were assayed by gas-liquid chromatography in cytosols of rat atrial and ventricular muscle cardiomyocytes. The tissues were assayed after the rats had been administered IP with the three cardioactive drugs, exerting a significant effect on their heart action: propranolol, pentylenetetrazol and reserpine. It was demonstrated that while in the atrial and ventricular cardiac muscle cytosols of control rats, arginine, glutamine and cysteine were detected in high levels (35.1% and 17.6%; 14.8% and 51.6%; 9.9% and 0.25% of the total free amino acids, respectively), all three drugs significantly reduced the total amounts of cytosolic free amino acids in both atrial and ventricular heart muscles. All three drugs (with reserpine in particular) modified the levels of arginine, cysteine, phenylalanine, tryptophan, isoleucine and tyrosine. The role of these amino acids in the heart muscle cytosol, and their involvement in the mechanism of action of these three cardioactive drugs, is discussed.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

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Proteinous Amino Acids in Muscle Cytosol of Rats' Heart, After Their Treatment with Propranolol, Pentylenetetrazol or Reserpine

et al. 2004

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“…We believe that branched-chain amino acids have distinct regulatory and metabolic effects on the cardiac muscle, in addition to their being energy-producing substrates for that tissue (Chua 1994;Young et al 1991). They also protect the heart muscle against myocardial ischemic injury and we suggested that isoleucine in the heart muscle also played a role of endogenous antiarrhythmic-like factor (Gabrys et al 2002a).…”

Section: Introductionmentioning

confidence: 92%

“…In previous studies from our laboratories, we investigated three branched-chain (lateral) amino acids: leucine, isoleucine, and valine (Gabrys et al 1999a;Gabrys et al 1999b;Gabrys et al 2000). We believe that branched-chain amino acids have distinct regulatory and metabolic effects on the cardiac muscle, in addition to their being energy-producing substrates for that tissue (Chua 1994;Young et al 1991).…”

Section: Introductionmentioning

confidence: 97%

Proteinous Amino Acids in Hearts' Muscle Cytosol of Rats Pretreated with Digoxin, Caffeine or Isoproterenol

et al. 2004

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Levels of the 19 proteinous amino acids and total free amino acids were assayed by gas-liquid chromatography in cytosols of rat atrial and ventricular muscle cardiomyocytes. The tissues were assayed after the rats had been exposed to the cardioactive drugs digoxin, caffeine, and isoproterenol, each having different mechanisms of action. We demonstrated that, in the atrial and ventricular cardiac muscle cytosol of control (untreated) rats, arginine, glutamine, and cysteine existed in their highest levels: 35.1% and 17.6%; 14.8% and 51.6%; 9.9% and 0.25% of the total free amino acids, respectively. The levels of the other amino acids in the atrial and ventricular cardiac muscle cytosols ranged between 0.1% and 10.0% of the total free amino acids. Digoxin, caffeine, and isoproterenol significantly reduced the total amount of cytosolic free amino acids in the atrial heart muscle cytosol to 7.6%, 9.0%, and 9.2% of the control value (100%), and in the ventricular heart muscle cytosol to 31.1%, 43.2%, and 28.3% of the control. The three drugs tested changed the cytosols' levels of arginine, cysteine, tryptophane, asparagine, and tyrosine in atrial and ventricular heart muscle cytosol, as compared to the control groups (calculated as a percent of the total free amino acids in the experimental groups). The role of proteinous amino acids in the function of the heart muscle and in the mechanism of action of these drugs on the mammalian heart is discussed.

Proteinous Amino Acids in Muscle Cytosol of Rats' Heart, After Their Treatment with Propranolol, Pentylenetetrazol or Reserpine

et al. 2004