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Effects of starvation on protein turnover in the rat heart in vivo and invitro
53 139 EFFECTS OF STARVATION O N PROTEIN TURNOVER IN THE RAT HEART IN v i v a A N D IN VITRO. D . M . Smith, V.R. Preedy, N . F . Kearney, P.H. Sugden. Department of Cardiac Medicine, Cardiothoracic Institute, London, W1N 2DX, England. Starvation of approximately 300g rats for 3 days reduced body weight by 21% and total ventricular protein and RNA contents by 15% and 28%, respectively. Protein synthesis was measured in viva by intravenous administration of 1.5 IJmol [4-3H] phe/g body wt. and in Vitro in working hearts perfused with 5mM-glucose. In viva, starvation reduced the ventricular fractional synthesis rate (FSR) of total protein from 9.0 + 0.7 to 5.44- 0.8%/day (P < 0.01, n = 7) and reduced the atrial FSR from 14.8 + 1.3 to 10.8 4- 1.0%/day (P < 0.05, n=7). Although there was a small (6- 10%) decrease in the RNA/protein ratio in both compartments, the major effect was to reduce the efficiency of protein synthesis (protein synthesis/RNA) by 39% in ventricles and 22% in atria. In vitro, starvation decreased the ventricular protein synthesis rate from 1.22 4- 0.05 (n=8) to 0.65 + 0.04 (n=6) and the atrial rate from 2.37 + 0.07 (n=8) to 1.41 4- 0.04 (n=6) nmol phe incorparated/2h/mg protein (P < 0.001). Efficiency of protein synthesis decreased by 3 2 - 3 8 % . Cardiac protein degradation was increased in viva by starvation although there was a decrease in vitro. These contradictory findings can be ratlonalised when effects of insulin on protein degradation are considered. Thus starvation decreases efficiency of Cardiac protein synthesis and RNA/protein ratio in viva and in vitro, and increases the rate of protein degradation in viva.
140 NON-HOMOGENEITY OF CONTRACTILE PROTEIN EXPRESSION IN THE HUMAN HEART: FUNCTIONAL IMPLICATIONS. P. Cummins, J.E. Humphreys, H.A. Janes and S.J. Lambert. Molecular Cardiology Unit, Department of Cardiovascular Medicine, University of Birmingham, Birmingham, U.K. The heart's ability to respond to normal and abnormal physiological demands depends to an unknown extent on its contractile protein isotype composition. We have mapped the isotypes of the contractile proteins, myosin (heavy and light chain subunits), tropomyosin (~ and ~ subunits) and troponin-I, to investigate whether isotype expression is homogeneous throughout the human myocardium. Myosin light chain isotypes differed in atria and ventricles in the adult and during development. Transitions between atrial and ventricular forms occurred at many developmental and adult ages and in pressure overload hypertrophy. Myosin heavy chain isotypes were less variable in the ventricle but atrial and ventricular types were expressed in the atria with marked quantitative differences between regions. Tropomyosin ~ and subunits varied in relative proportions and correlated with changing contraction speeds; troponin-I expression was homogeneous throughout the myocardlum. The pattern of contractile protein expression differed markedly in the small and large mammalian myocardium and may limit the physiological response in man.
141 ENDOGENOUS OPIOID SYSTEM IN ACUTE MYOCARDIAL INFARCTION. P. Bernardi, R. Grimaldi, F. Ghezzi, C. Minelli, M. Cavazza, L. Bastagli, *C. C16, *C. Ventura, **R.A. Genazzani, **F. Petraglia, **F. Facchinetti, ~ Ligabue. II Medical Clinic, St. Orsola Hospital and * Biochemistry Institute, University of Bologna; ** Dept. of Ob. and Gyn., University of Modena; o Centralized laboratory, Malpighi Hospital, Bologna, Italy. In order to investigate the endogenous opioid system involvement during acute myocardial infarction (AMI), plasmatic ~-endorphin levels were measured and naloxone administration effects were evaluated. High levels of plasmatic ~ - e n d o r p h i n were found in patients with uncomplicated kMI. In these patients the ~-endorphin, ~ - l i p o trophin and cortisol cyrcadian rhythm was completely altered. However the highest ~ - e n d o r p h i n values were observed in cardiogenic shock and after electric defibrillation for hypercinetic ventricular arrhythmias. A significant hemodynamic parameter improvement was produced by naloxone administration in patients with cardiogenic shoc~ The same positive effects were observed in patients with hypotension-bradycardia syndrome in which naloxone administration produced an immediate and permanent blood pressure and heart rate increase to normal values. No effects were found in patients with uncomplicated AMI or in healthy subjects.
140 NON-HOMOGENEITY OF CONTRACTILE PROTEIN EXPRESSION IN THE HUMAN HEART: FUNCTIONAL IMPLICATIONS. P. Cummins, J.E. Humphreys, H.A. Janes and S.J. Lambert. Molecular Cardiology Unit, Department of Cardiovascular Medicine, University of Birmingham, Birmingham, U.K. The heart's ability to respond to normal and abnormal physiological demands depends to an unknown extent on its contractile protein isotype composition. We have mapped the isotypes of the contractile proteins, myosin (heavy and light chain subunits), tropomyosin (~ and ~ subunits) and troponin-I, to investigate whether isotype expression is homogeneous throughout the human myocardium. Myosin light chain isotypes differed in atria and ventricles in the adult and during development. Transitions between atrial and ventricular forms occurred at many developmental and adult ages and in pressure overload hypertrophy. Myosin heavy chain isotypes were less variable in the ventricle but atrial and ventricular types were expressed in the atria with marked quantitative differences between regions. Tropomyosin ~ and subunits varied in relative proportions and correlated with changing contraction speeds; troponin-I expression was homogeneous throughout the myocardlum. The pattern of contractile protein expression differed markedly in the small and large mammalian myocardium and may limit the physiological response in man.
141 ENDOGENOUS OPIOID SYSTEM IN ACUTE MYOCARDIAL INFARCTION. P. Bernardi, R. Grimaldi, F. Ghezzi, C. Minelli, M. Cavazza, L. Bastagli, *C. C16, *C. Ventura, **R.A. Genazzani, **F. Petraglia, **F. Facchinetti, ~ Ligabue. II Medical Clinic, St. Orsola Hospital and * Biochemistry Institute, University of Bologna; ** Dept. of Ob. and Gyn., University of Modena; o Centralized laboratory, Malpighi Hospital, Bologna, Italy. In order to investigate the endogenous opioid system involvement during acute myocardial infarction (AMI), plasmatic ~-endorphin levels were measured and naloxone administration effects were evaluated. High levels of plasmatic ~ - e n d o r p h i n were found in patients with uncomplicated kMI. In these patients the ~-endorphin, ~ - l i p o trophin and cortisol cyrcadian rhythm was completely altered. However the highest ~ - e n d o r p h i n values were observed in cardiogenic shock and after electric defibrillation for hypercinetic ventricular arrhythmias. A significant hemodynamic parameter improvement was produced by naloxone administration in patients with cardiogenic shoc~ The same positive effects were observed in patients with hypotension-bradycardia syndrome in which naloxone administration produced an immediate and permanent blood pressure and heart rate increase to normal values. No effects were found in patients with uncomplicated AMI or in healthy subjects.