Author + information
- Received March 18, 1996
- Revision received May 31, 1996
- Accepted June 17, 1996
- Published online November 1, 1996.
- Toshihisa Anzai, MD** (, )
- Tsutomu Yoshikawa, MD,
- Akiyasu Baba, MD,
- Hiroshi Nishimura, MD,
- Hiroto Shiraki, MD,
- Keiichi Nagami, MD,
- Masahiro Suzuki, MD,
- Yumiko Wainai, MD and
- Satoshi Ogawa, MD
- ↵**Present address and address for correspondence: Dr. Toshihisa Anzai, Cardiology Section (9111A), Department of Veterans Affairs, University of California, San Diego, 3350 La Jolla Village Drive, San Diego, California 92161.
Objectives. The purpose of this study was to assess the effect of myocardial sympathetic denervation on the chamber-specific alteration of beta-adrenergic signaling in left ventricular failure in rabbits.
Background. Local abnormalities in sympathetic nerve terminals, including the neuronal reuptake of norepinephrine, are thought to be responsible for the chamber-specific regulation of beta-adrenergic signaling in heart failure.
Methods. Sixteen rabbits were given 6-hydroxydopamine, 25 mg/kg body weight intravenously on days 1 and 2 and 50 mg/kg intravenously on days 7 and 8. Another 16 rabbits received vehicle. Aortic regurgitation was induced in eight of the 6-hydroxydopamine—treated and eight of the vehicle-treated rabbits on day 14. Another eight of the 6-hydroxydopamine—treated and eight of the vehicletreated rabbits underwent a sham operation. The hearts were excised for biochemical analysis on day 21.
Results. Hemodynamic characteristics on day 21 showed left ventricular failure in both the aortic regurgitation groups. The plasma norepinephrine concentration on day 21 was higher in both the aortic regurgitation groups than in the sham groups. The beta-adrenoceptor densities and isoproterenol plus 5′guanylylimidodiphosphate-, 5′-guanylylimidodiphosphate- and sodium fluoride-stimulated adenylyl cyclase activities were decreased only in the failing left ventricle of the vehicle-pretreated aortic regurgitation group, but in both ventricles of the 6-hydroxydopamine-pretreated aortic regurgitation group. The basal and forskolin-stimulated adenylyl cyclase activities were similar in both the aortic regurgitation groups and in the sham groups.
Conclusions. Sympathetic denervation prevented chamberspecific alterations in beta-adrenergic signaling in acute left ventricular failure. Local loss of sympathetic nerve endings, and especially the defective neuronal norepinephrine reuptake, are likely to be responsible for the chamber-specific alteration of the beta-adrenoceptor-G protein-adenylyl cyclase system in heart failure in rabbits.
- Received March 18, 1996.
- Revision received May 31, 1996.
- Accepted June 17, 1996.
- American College of Cardiology