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Food restriction promotes downregulation of myocardial L-type Ca2+ channels

Loreta Casquel De Tomasi1, Alessandro Bruno, Mário Mateus Sugizaki

  • 1Department of Clinical Cardiology, School of Medicine, UNESP - State University Júlio Mesquita Filho, Rubião Júnior, Botucatu, São Paulo, Brazil.

Canadian Journal of Physiology and Pharmacology
|June 16, 2009
PubMed

Insights

Food restriction impairs heart function by reducing L-type calcium channels. This study in rats found that restricted diets decrease calcium channel protein, explaining cardiac dysfunction.

Area of Science:

  • Cardiovascular Physiology
  • Nutritional Science
  • Molecular Cardiology

Background:

  • Food restriction (FR) is known to negatively impact myocardial performance.
  • The underlying mechanisms linking FR to cardiac dysfunction are not fully understood.
  • Myocardial L-type Ca2+ channels are potential contributors to cardiac dysfunction.

Purpose of the Study:

  • To investigate the effects of food restriction on the function and expression of myocardial L-type Ca2+ channels.
  • To determine if alterations in L-type Ca2+ channels mediate cardiac dysfunction induced by FR.

Main Methods:

  • Male Wistar rats were subjected to 90 days of either a control or a restricted diet (50% of control intake).
  • Myocardial performance was assessed using isolated left ventricular papillary muscles.
  • L-type Ca2+ channel function was evaluated using the blocker diltiazem.
  • Changes in channel expression were analyzed via mRNA and protein levels.

Main Results:

  • Food restriction led to decreased body weight and ventricular weights.
  • Diltiazem caused a greater blockade of developed tension in FR rats compared to controls.
  • Protein expression of L-type Ca2+ channels was significantly reduced in FR rats.
  • mRNA expression of L-type Ca2+ channels remained similar between groups.

Conclusions:

  • Food restriction downregulates the protein content of myocardial L-type Ca2+ channels.
  • Reduced L-type Ca2+ channels likely contribute to the impaired myocardial performance observed in FR animals.
  • This study elucidates a potential molecular mechanism for cardiac dysfunction due to dietary restriction.

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