AJP - Heart and Circulatory Physiology, Vol 243, Issue 2 175-H180, Copyright © 1982 by American Physiological Society
Selective sympathetic neural changes in hypertrophied right ventricle
P. G. Schmid, D. D. Lund, J. A. Davis, C. A. Whiteis, R. K. Bhatnagar and R. Roskoski Jr
Selective pressure overload of the right ventricle in guinea pigs resulted
in early and sustained reductions in tyrosine hydroxylase and
dopamine-beta-hydroxylase activities in the right ventricle. No changes in
tyrosine hydroxylase activity were detected in stellate ganglia sinoatrial
(SA) nodal region, atrioventricular (AV) nodal region, or left ventricle.
Reductions in tyrosine hydroxylase activity in stressed right ventricle
were similar regardless of duration of pulmonary artery constriction,
extent of hypertrophy, presence or absence of hepatic congestion, and
preservation or depletion of catecholamines. The changes may represent
localized loss of sympathetic nerve fibers; factors involved directly in
the process of pressure-overload-induced hypertrophy may be responsible.
However, sympathetic nerves remaining in hypertrophied ventricle respond
normally to cold-induced sympathetic activation. The reduction in tyrosine
hydroxylase activity and the maintenance of norepinephrine turnover in
residual innervation to hypertrophied right ventricle support the concept
that sympathetic neural regulation of hypertrophied cardiac tissue is
altered but not lost.
