title: Effects of chronic progressive myocardial hypertrophy on indexes of cardiac autonomic innervation.
abstract: The development of cardiac hypertrophy is associated with marked changes in cardiac autonomic innervation. Significant and sustained reductions of myocardial catecholamine stores and activities of tyrosine hydroxylase and dopamine beta-hydroxylase have been reported in models of acutely induced ventricular hypertrophy. Conversely, activity of choline acetyltransferase, a marker of parasympathetic nervous function, shows transient increases during the development of acute right ventricular hypertrophy. The potential physiological importance of these changes prompted us to examine a clinically more relevant model of slowly progressive ventricular hypertrophy. Application of a loose band around the pulmonary artery of weanling guinea pigs resulted in a growth-related progressive right ventricular pressure overload. Right ventricular weight-to-body-weight ratio was increased significantly and progressively at 9 and 18 weeks in banded animals (0.92 +/- 0.05 and 1.31 +/- 0.11 mg/g, respectively, p less than 0.01) compared with sham-operated controls (0.55 +/- 0.02 and 0.59 +/- 0.01 mg/g, respectively) but showed no further gain at 27 weeks (1.41 +/- 0.10 mg/g). Activities of tyrosine hydroxylase and dopamine beta-hydroxylase remained unchanged in all experiment groups, while right ventricular contents of norepinephrine in banded animals at 18 and 27 weeks exhibited sustained and progressive increases (2.45 +/- 0.11 and 3.40 +/- 0.19 micrograms/right ventricle, respectively) over controls (1.80 +/- 0.13 and 2.40 +/- 0.22 micrograms/right ventricle, respectively, p less than 0.01). The activity of choline acetyltransferase was markedly elevated in banded animals at 18 weeks (32.6 +/- 2.7 nmol/hr/right ventricle) but returned to baseline by 27 weeks (22.8 +/- 1.4 nmol/hr/right ventricle).(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000818:Animals; D001341:Autonomic Nervous System / Q000378:metabolism / Q000503:physiopathology*; D001835:Body Weight; D006332:Cardiomegaly / Q000378:metabolism / Q000503:physiopathology*; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D004195:Disease Models, Animal; D004299:Dopamine beta-Hydroxylase / Q000378:metabolism; D006168:Guinea Pigs; D006321:Heart / Q000294:innervation* / Q000503:physiopathology; D008297:Male; D009206:Myocardium / Q000201:enzymology / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism; D009929:Organ Size; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
chemical_list: D014446:Tyrosine 3-Monooxygenase; D004299:Dopamine beta-Hydroxylase; D002795:Choline O-Acetyltransferase; D009638:Norepinephrine