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Binding of adenine nucleotides induces conformational transformations of sarcoplasmic reticulum Ca-ATPase attended by changes of cation binding properties of the enzyme
J Mol Cell Cardiol21 544
(Supplement
11)(1989)
SARCOPLAsMICRETIcuLuMCAlCIUMUPTAKEIN'ME STUNNEDMYOXRDIUM. U.LiaWuno, R.Zucchi, S.Ronca-Testoni, P.Gslbani, G.Ronca, M.Msriani. Depsrtment of Cardiology and Institute of Biological Chemistry, Piss, Italy. We studied sancoplasmic reticula (SR) calcium uptake in an isolated rat heart model of stunned myocardium. Control hearts (CH n=6) were perfused with the irking heart technique for 40 min. Stunned hearts (SH n=6) underwent 10 min control v,orking heart perfusion, 10 min global normothennic ischemia, 10 min Lengendorff reperfusion and 10 min postischemic working heart perfusion, which showed a persistent 15-20% decrease in cardiac output and minute work. $&lhesrts ware homogenized and amembrane fraction enriched in SR was prepared. CslciLnn uptake wss m%sured in basal conditions and in the presence of 0.002 mM ruthenium red (RR), tiich inhibits calcium efflux tzhrou& SR calciumchannels. In SH cslciwnuptske was lower than in CH (4822~s 67211 nmol/min/mg protein), and showed a subnormal increase in the presence of RR (56+3 vs 101218 nmol/min/mg protein, P less than 0.05; percentage increase 1722 vs 48~& p less than 0.01). SR diction is known to be impsired during ischemia. W findings show that SR dysfWcticn persist to some extent in the stunned myocardium and might contribute to the contractile inpsirment present in this condition.
545 BINDING
OF ADENINE NUCLEOTIDES INDUCES CONFORMATIONAL TRANSFORMATIONS OF SARCOPLASMIC RETICULUM Ca-ATPase ATTENDED BY CHANGES OF CATION BINDING PROPERTIES OF THE ENZYME. I.M.Timonin, S.N.Dvoryantsev, M.I.Kaykov, V.V. D.O.Levitsky, E.K.Ruuge. Institute of Experimental Cardiology, Petrov, USSR Cardiology Research Center, Moscow, USSR. Binding of ATP, ADP, and their non-hydrolizing analogs, AMPPNP and ADP-P-S, with sarcoplasmic reticulum membranes induces the conformatiIt is revealed in the following changes onal rearrangement of Ca-ATPase. of cation binding characteristics: the Kd value of the centers I of the enzyme (cation binding centers interacting with calcium ions in micromolar concentrations) for sodium ions decreases 3 times; the number of the number of the centers II (cation the centers I increases 4-6 times; binding centers interacting with calcium ions in millimolar concentrations) decreases twice. Other nucleotides (GTP, ITP, UTP, CTP, CAMP, cGMP, AMP) and acetylphosphate do not alter the ratio between the centers. These changes correspond to conformational rearrangements of Ca-ATPase; they take place under conditions providing well-known transformation as well as upon saturation of high-affinity binding sites of the E*-E The transformation of Ca-ATPase induced by adeenzyme by calcium ions. nine nucleotides protects the centers I and II from tryptic digestion.
546
Tetrandrine (Tet) on Sarcoplasmic Reticulum in Ca2+, MgP+-ATPase Compared to other Amphiphile. Chen LanYing, Chen Xu, Cardiovascular Institute, Chinese Academy of Medical Sciences, Beijing China. Tet, a bisbenzylisoquinoline alkaloid, isolated from the root of Stephania tetrandra S. Moore, is the amphiphile with I+)-chame, and oossesses antihvpertensive and antiarrhvthmic effects. Tet was compared with Cl8 saturated fatty amine (&a@ amine, SM), another amphiphile with (+)
(Supplement
11)(1989)
SARCOPLAsMICRETIcuLuMCAlCIUMUPTAKEIN'ME STUNNEDMYOXRDIUM. U.LiaWuno, R.Zucchi, S.Ronca-Testoni, P.Gslbani, G.Ronca, M.Msriani. Depsrtment of Cardiology and Institute of Biological Chemistry, Piss, Italy. We studied sancoplasmic reticula (SR) calcium uptake in an isolated rat heart model of stunned myocardium. Control hearts (CH n=6) were perfused with the irking heart technique for 40 min. Stunned hearts (SH n=6) underwent 10 min control v,orking heart perfusion, 10 min global normothennic ischemia, 10 min Lengendorff reperfusion and 10 min postischemic working heart perfusion, which showed a persistent 15-20% decrease in cardiac output and minute work. $&lhesrts ware homogenized and amembrane fraction enriched in SR was prepared. CslciLnn uptake wss m%sured in basal conditions and in the presence of 0.002 mM ruthenium red (RR), tiich inhibits calcium efflux tzhrou& SR calciumchannels. In SH cslciwnuptske was lower than in CH (4822~s 67211 nmol/min/mg protein), and showed a subnormal increase in the presence of RR (56+3 vs 101218 nmol/min/mg protein, P less than 0.05; percentage increase 1722 vs 48~& p less than 0.01). SR diction is known to be impsired during ischemia. W findings show that SR dysfWcticn persist to some extent in the stunned myocardium and might contribute to the contractile inpsirment present in this condition.
545 BINDING
OF ADENINE NUCLEOTIDES INDUCES CONFORMATIONAL TRANSFORMATIONS OF SARCOPLASMIC RETICULUM Ca-ATPase ATTENDED BY CHANGES OF CATION BINDING PROPERTIES OF THE ENZYME. I.M.Timonin, S.N.Dvoryantsev, M.I.Kaykov, V.V. D.O.Levitsky, E.K.Ruuge. Institute of Experimental Cardiology, Petrov, USSR Cardiology Research Center, Moscow, USSR. Binding of ATP, ADP, and their non-hydrolizing analogs, AMPPNP and ADP-P-S, with sarcoplasmic reticulum membranes induces the conformatiIt is revealed in the following changes onal rearrangement of Ca-ATPase. of cation binding characteristics: the Kd value of the centers I of the enzyme (cation binding centers interacting with calcium ions in micromolar concentrations) for sodium ions decreases 3 times; the number of the number of the centers II (cation the centers I increases 4-6 times; binding centers interacting with calcium ions in millimolar concentrations) decreases twice. Other nucleotides (GTP, ITP, UTP, CTP, CAMP, cGMP, AMP) and acetylphosphate do not alter the ratio between the centers. These changes correspond to conformational rearrangements of Ca-ATPase; they take place under conditions providing well-known transformation as well as upon saturation of high-affinity binding sites of the E*-E The transformation of Ca-ATPase induced by adeenzyme by calcium ions. nine nucleotides protects the centers I and II from tryptic digestion.
546
Tetrandrine (Tet) on Sarcoplasmic Reticulum in Ca2+, MgP+-ATPase Compared to other Amphiphile. Chen LanYing, Chen Xu, Cardiovascular Institute, Chinese Academy of Medical Sciences, Beijing China. Tet, a bisbenzylisoquinoline alkaloid, isolated from the root of Stephania tetrandra S. Moore, is the amphiphile with I+)-chame, and oossesses antihvpertensive and antiarrhvthmic effects. Tet was compared with Cl8 saturated fatty amine (&a@ amine, SM), another amphiphile with (+)