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Age-related changes in the influence of Ca2+ on rat cardiac mitochondrial energetics
J Mel Cell Cardiol 24
(Supplement
I)
(1992)
PmW,-1dFOURIER TRANSFORM ANALYSIS OF CaZ+ TRANSIENTS FROM ISOLATED PERFUSED BEATING RAT . -- . . HEART Ali Azzawi, Mark L Field, Peter Styles, George K Radda. Dept. Biochemistry, South Parks Road, Oxford University, Oxlord OX1 3OU, U.K. The myocardial Ca*+ transient profile is thought to be the result of several distinct cellular fluxes: extracellular influx/efflux and sarcoplasmic reticular influxlefflux. Figure (A) shows beat to beat Ca2+ transients measured from the epicardial surface of isolated rat heart using the fluorescent Ca*+ indicator FURAP-AM. In order to obtain a numerical description of the nature of these Ca*+ transients, we applied Fourier transform UI) (B) analysis to the signal. This process reveals harmonic components as shown in figure (B). The relative fl intensities of these harmonic frequencies were lound to -4 change with certain physiological events. Although each component does not directly correlate with a particular biochemical event, the relative intensities 01 high and low frequency harmonics give an indication of fast and slow cellular Ca*+ handling. It is concluded that Fourier transformation of Can+ transients is uselut in describing changes in the myocardial Ca*+ profile.
p-05-15
EFFECTS OF SAPONIN ON CONTRACTILITY, INTRACELLULAR Ca2+ AND FLUIDITY OF H. Iahida. Y. Hirota, H. Nakazawa, PLASMA MEMBRANE IN CULTURED HEART CELLS. H. Okino, Dept. of Physiol. 2, School of Medicine. Tokai Univ.. Japan. Although it is known that “sub-skinning’ concentrations of saponin have a positive the underlying inotropic action on cardiac muscles, mechanism for the effect is not clarified yet. We examined that the effect of digitonin ( one of the representatives of the intracellular CP’ ([Ca2+li) and the fluidity of plasma membrane in saponin ) on cultured heart cells when digitonin produced a positive inotropic effect. The membrane fluidity was evaluated using the fluorescence recovery after photobleaching method. This system measures a lateral transport of fluorescent lipid analog, DiI-Cl& in the plasma membrane. Low concentrations ( 10e7 to 10% M ) of digitonin produced an increase in the ampli%de of cell motion accompany with the argument of CCH’li within 15 min. At 2.5 X 10 M or more. however, digitonlo induced an oscillation and then a contracture; indicating that the concentration is beyond the ‘sub-skinning’ level. At 15 min after exposure to 2 X 1 -7 t,” O~;inIO~$e c3 11 membrane fluidity was significantly decreased from 0.34 x 10-8 c /set (P
P-0516Cell Damage and Ca Overload Induced by Arachidonate Lipoxygenase Reaction in Single Ventricular Myocyte. Hiroshi Oe, Tsunehiko Kuzuya, Shiro Hoshida, Nobushige Yamashita, Hisakazu Fuji, Michihiko Tada. Department of Medicine and Pathophysiology, Osaka University, Osaka, Japan. To investigate the direct effect of arachidonate lipoxygenase reaction on the contractility and cytosolic Ca ([Cali) of the myocardium, single rat cardiac myocyte (M) loaded with Indo-l was superfused with Tyrode solution containing with arachidonic acid (AA,30pM) mixed with soybean lipoxygenase (LOX) under field stimulation at 1Hz. The time when twitch amplitude increased by 120% was defined as T (min). [Cali was estimated by the ratio (R) of cell fluorescence of 2 wavelength (4lOnm/485nm, excitation 340nm), and the increase of mean R after 30min super-fusion was defined as Amean R(B). AA-LOX induced the increase of twitch amplitude (T=20.&2.9) associated with the increased [Cali (Amean R=l2.2&4.0) followed by spontaneous oscillation and contracture. Although nicardi ine (2pM) did not prevent these effect (T=24.3f6.4, Amean R=9.!%4.0), both ascorbic acid (Vit C, lo- BM) and a-tocopherol (Vit E, 10e5M) potently suppressed (Vit C; T>45, &neanR=2.1+1.1 Vit E; T=36.3M.O, Amean R=l.5ti.2). These results indicated that AA-LOX reaction increase the contractility and [Cali of M leading to oscillatory beating and contracture and that lipid peroxidation induced by AALOX reaction play an important role for the cell damage. S.206
(Supplement
I)
(1992)
PmW,-1dFOURIER TRANSFORM ANALYSIS OF CaZ+ TRANSIENTS FROM ISOLATED PERFUSED BEATING RAT . -- . . HEART Ali Azzawi, Mark L Field, Peter Styles, George K Radda. Dept. Biochemistry, South Parks Road, Oxford University, Oxlord OX1 3OU, U.K. The myocardial Ca*+ transient profile is thought to be the result of several distinct cellular fluxes: extracellular influx/efflux and sarcoplasmic reticular influxlefflux. Figure (A) shows beat to beat Ca2+ transients measured from the epicardial surface of isolated rat heart using the fluorescent Ca*+ indicator FURAP-AM. In order to obtain a numerical description of the nature of these Ca*+ transients, we applied Fourier transform UI) (B) analysis to the signal. This process reveals harmonic components as shown in figure (B). The relative fl intensities of these harmonic frequencies were lound to -4 change with certain physiological events. Although each component does not directly correlate with a particular biochemical event, the relative intensities 01 high and low frequency harmonics give an indication of fast and slow cellular Ca*+ handling. It is concluded that Fourier transformation of Can+ transients is uselut in describing changes in the myocardial Ca*+ profile.
p-05-15
EFFECTS OF SAPONIN ON CONTRACTILITY, INTRACELLULAR Ca2+ AND FLUIDITY OF H. Iahida. Y. Hirota, H. Nakazawa, PLASMA MEMBRANE IN CULTURED HEART CELLS. H. Okino, Dept. of Physiol. 2, School of Medicine. Tokai Univ.. Japan. Although it is known that “sub-skinning’ concentrations of saponin have a positive the underlying inotropic action on cardiac muscles, mechanism for the effect is not clarified yet. We examined that the effect of digitonin ( one of the representatives of the intracellular CP’ ([Ca2+li) and the fluidity of plasma membrane in saponin ) on cultured heart cells when digitonin produced a positive inotropic effect. The membrane fluidity was evaluated using the fluorescence recovery after photobleaching method. This system measures a lateral transport of fluorescent lipid analog, DiI-Cl& in the plasma membrane. Low concentrations ( 10e7 to 10% M ) of digitonin produced an increase in the ampli%de of cell motion accompany with the argument of CCH’li within 15 min. At 2.5 X 10 M or more. however, digitonlo induced an oscillation and then a contracture; indicating that the concentration is beyond the ‘sub-skinning’ level. At 15 min after exposure to 2 X 1 -7 t,” O~;inIO~$e c3 11 membrane fluidity was significantly decreased from 0.34 x 10-8 c /set (P
P-0516Cell Damage and Ca Overload Induced by Arachidonate Lipoxygenase Reaction in Single Ventricular Myocyte. Hiroshi Oe, Tsunehiko Kuzuya, Shiro Hoshida, Nobushige Yamashita, Hisakazu Fuji, Michihiko Tada. Department of Medicine and Pathophysiology, Osaka University, Osaka, Japan. To investigate the direct effect of arachidonate lipoxygenase reaction on the contractility and cytosolic Ca ([Cali) of the myocardium, single rat cardiac myocyte (M) loaded with Indo-l was superfused with Tyrode solution containing with arachidonic acid (AA,30pM) mixed with soybean lipoxygenase (LOX) under field stimulation at 1Hz. The time when twitch amplitude increased by 120% was defined as T (min). [Cali was estimated by the ratio (R) of cell fluorescence of 2 wavelength (4lOnm/485nm, excitation 340nm), and the increase of mean R after 30min super-fusion was defined as Amean R(B). AA-LOX induced the increase of twitch amplitude (T=20.&2.9) associated with the increased [Cali (Amean R=l2.2&4.0) followed by spontaneous oscillation and contracture. Although nicardi ine (2pM) did not prevent these effect (T=24.3f6.4, Amean R=9.!%4.0), both ascorbic acid (Vit C, lo- BM) and a-tocopherol (Vit E, 10e5M) potently suppressed (Vit C; T>45, &neanR=2.1+1.1 Vit E; T=36.3M.O, Amean R=l.5ti.2). These results indicated that AA-LOX reaction increase the contractility and [Cali of M leading to oscillatory beating and contracture and that lipid peroxidation induced by AALOX reaction play an important role for the cell damage. S.206