Diastolic dysfunction and altered energetics in the alphaMHC403/+ mouse model of familial hypertrophic cardiomyopathy.

M Spindler, KW Saupe, ME Christe… - The Journal of …, 1998 - Am Soc Clin Investig
M Spindler, KW Saupe, ME Christe, HL Sweeney, CE Seidman, JG Seidman, JS Ingwall
The Journal of clinical investigation, 1998Am Soc Clin Investig
An arginine to glutamine missense mutation at position 403 of the beta-cardiac myosin
heavy chain causes familial hypertrophic cardiomyopathy. Here we study mice which have
this same missense mutation (alphaMHC403/+) using an isolated, isovolumic heart
preparation where cardiac performance is measured simultaneously with cardiac energetics
using 31P nuclear magnetic resonance spectroscopy. We observed three major alterations
in the physiology and bioenergetics of the alphaMHC403/+ mouse hearts. First, while there …
An arginine to glutamine missense mutation at position 403 of the beta-cardiac myosin heavy chain causes familial hypertrophic cardiomyopathy. Here we study mice which have this same missense mutation (alphaMHC403/+) using an isolated, isovolumic heart preparation where cardiac performance is measured simultaneously with cardiac energetics using 31P nuclear magnetic resonance spectroscopy. We observed three major alterations in the physiology and bioenergetics of the alphaMHC403/+ mouse hearts. First, while there was no evidence of systolic dysfunction, diastolic function was impaired during inotropic stimulation. Diastolic dysfunction was manifest as both a decreased rate of left ventricular relaxation and an increase in end-diastolic pressure. Second, under baseline conditions alphaMHC403/+ hearts had lower phosphocreatine and increased inorganic phosphate contents resulting in a decrease in the calculated value for the free energy released from ATP hydrolysis. Third, hearts from alphaMHC403/+ hearts that were studied unpaced responded to increased perfusate calcium by decreasing heart rate approximately twice as much as wild types. We conclude that hearts from alphaMHC403/+ mice demonstrate work load-dependent diastolic dysfunction resembling the human form of familial hypertrophic cardiomyopathy. Changes in high-energy phosphate content suggest that an energy-requiring process may contribute to the observed diastolic dysfunction.
The Journal of Clinical Investigation