Related Experiment Videos
Myocardial presynaptic and postsynaptic autonomic dysfunction in hypertrophic cardiomyopathy
M Schäfers1, D Dutka, C G Rhodes
1Department of Nuclear Medicine, University of Münster, Germany.
Circulation Research
|January 24, 1998
Summary
Hypertrophic cardiomyopathy (HCM) patients show reduced beta-adrenoceptor (betaAR) density and impaired catecholamine reuptake in the heart. This suggests higher local norepinephrine levels contribute to HCM progression.
Area of Science:
- Cardiology
- Nuclear Medicine
- Pharmacology
Background:
- Hypertrophic cardiomyopathy (HCM) is a genetic heart condition influenced by factors like autonomic dysfunction.
- Previous studies indicated reduced beta-adrenoceptor (betaAR) density in HCM, correlating with disease progression.
- The role of catecholamine reuptake in HCM's phenotypic expression requires further investigation.
Purpose of the Study:
- To test the hypothesis that reduced betaAR density in HCM is linked to impaired catecholamine reuptake (uptake 1) by sympathetic nerve terminals.
- To investigate if impaired uptake 1 leads to increased local norepinephrine concentration in HCM patients.
- To correlate myocardial betaAR density and catecholamine reuptake function in HCM.
Main Methods:
- Utilized positron emission tomography (PET) with [11C]hydroxyephedrine ([11C]HED) to assess myocardial presynaptic catecholamine reuptake (volume of distribution, Vd) in 9 HCM patients.
- Employed PET with [11C]CGP 12177 ([11C]CGP) to measure beta-adrenoceptor (betaAR) density (Bmax) in 13 HCM patients.
- Compared PET imaging results from HCM patients with those from healthy control subjects for both ligands.
Main Results:
- HCM patients exhibited significantly reduced myocardial Vd of [11C]HED (33.4+/-4.3 mL/g) compared to controls (71.0+/-18.8 mL/g, P<.001).
- Myocardial betaAR density was also significantly lower in HCM patients (7.3+/-2.6 pmol/g) than in controls (10.2+/-2.9 pmol/g, P=.008).
- Six patients studied with both tracers showed consistent reductions.
Conclusions:
- The findings support the hypothesis that myocardial betaAR downregulation in HCM is associated with impaired catecholamine reuptake (uptake 1).
- This impaired uptake mechanism likely results in elevated local norepinephrine levels within the myocardium of HCM patients.
- These alterations in sympathetic nerve terminal function may contribute to the progression and phenotypic expression of HCM.