Pulmonary artery banding alters the expression of Ca2+ transport proteins in the right atrium in rabbits

Am J Physiol Heart Circ Physiol. 2009 Jun;296(6):H1933-9. doi: 10.1152/ajpheart.00026.2009. Epub 2009 Apr 17.

Abstract

Following pulmonary artery banding (PAB), the contractile function of right ventricle diminishes over time. Subsequently, the right atrium (RA) has to contract against a higher afterload, but it is unknown to what extent ventricular dysfunction has an effect on the atrial contractility. We hypothesized that right ventricular pressure overload may have an affect on atrial contractility and Ca(2+) transport protein expression. Therefore, we induced pressure overload of the right ventricle by PAB for 10 wk in rabbits and examined the changes in the expression of Ca(2+) transport proteins in the atrium. We demonstrate that PAB significantly decreased the expression of sarco(endo)plasmic reticulum Ca(2+)-ATPase (Serca) 2a while expression of Na(+)/Ca(2+) exchanger-1 was significantly upregulated in the RA but not in the left atria of rabbit hearts, indicating that pressure is the major trigger. A decrease in Serca2a expression was concomitant with a significant decrease in sarcolipin (SLN), possibly indicating a compensatory role of SLN. The decreased expression of SLN was unable to completely restore sarcoplasmic reticulum Ca(2+) uptake function of Serca2a. Functional contractile assessments in isolated trabeculae showed no difference between PAB- and sham-operated rabbits at 1 Hz but displayed an enhanced force development at higher frequencies and in the presence of isoproterenol, while twitch timing was unaffected. Our results indicate that right ventricular mechanical overload due to PAB affects the expression of the Ca(2+)-handling proteins in the RA in rabbits.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / metabolism
  • Cardiotonic Agents / pharmacology
  • Heart Atria / metabolism
  • Heart Atria / pathology
  • Hypertrophy, Right Ventricular / metabolism*
  • Hypertrophy, Right Ventricular / physiopathology*
  • Isoproterenol / pharmacology
  • Male
  • Myocardial Contraction / drug effects
  • Myocardial Contraction / physiology
  • Myocardium / metabolism
  • Myocardium / pathology
  • Pulmonary Artery / physiopathology*
  • Rabbits
  • Sarcoplasmic Reticulum / metabolism
  • Sarcoplasmic Reticulum Calcium-Transporting ATPases / metabolism*
  • Sodium-Calcium Exchanger / metabolism*

Substances

  • Cardiotonic Agents
  • Sodium-Calcium Exchanger
  • Sarcoplasmic Reticulum Calcium-Transporting ATPases
  • Isoproterenol
  • Calcium