Abstract
Cardiac contractility depends on calcium sensitivity of the myofilaments and cytosolic free calcium concentration ([Ca2+]i) during activation. During development, the cardiac troponin T isoform cTnT1 is replaced by shorter cTnT isoforms, including cTnT4, and changes occur in other myofibrillar proteins and in calcium regulation. We expressed rabbit recombinant (r)cTnT1 and rcTnT4 in Spodoptera frugiperda cells and determined their effect on calcium binding to TnC in solution and on the calcium sensitivity of myofilaments in skinned rabbit ventricular fibers in vitro. We measured [Ca2+]i and L-type calcium current (ICa) in ventricular myocytes from 3-wk-old and adult rabbits. The dissociation constant (Kd) of Ca-TncTnT1 in solution was smaller than that of Ca-TncTnT4 (mean ± SE: 0.52 ± 0.08 μmol/L versus 0.83 ± 0.09 μmol/L). The Ca2+ sensitivity of force development was greater in fibers reconstituted with rcTnT1 (pCa50 6.07 ± 0.04) than those reconstituted with rcTnT4 (pCa50 5.75 ± 0.07). Systolic [Ca]i was lower in 3-wk-old than adult cells (443 ± 35 nmol/L versus 882 ± 88 nmol/L) as was ICa (5.8 ± 0.9 pA/pF versus 14.2 ± 1.6 pA/pF). The higher calcium sensitivity of Tn-Ca binding and of force development conferred by rcTnT1 suggest that higher neonatal cTnT1 expression may partially compensate for the lower systolic [Ca2+]i.
Similar content being viewed by others
Log in or create a free account to read this content
Gain free access to this article, as well as selected content from this journal and more on nature.com
or
Abbreviations
- IAANS:
-
2-[4′-(iodoacetamido)aniline]-naphthalene-6-sulfonate
- MOPS:
-
3-(N-morpholino)propane-sulfonate
References
Friedman WF 1972 The intrinsic physiologic properties of the developing heart. In: Friedman WF, Lesch M, Sonnenblick EH (eds) Progress in Cardiovascular Diseases: Neonatal Heart Disease. Grune & Stratton, New York, pp 87–111
Nassar R, Reedy MC, Anderson PA 1987 Developmental changes in the ultrastructure and sarcomere shortening of the isolated rabbit ventricular myocyte. Circ Res 61: 465–483
Siedner S, Kruger M, Schroeter M, Metzler D, Roell W, Fleischmann BK, Hescheler J, Pfitzer G, Stehle R 2003 Developmental changes in contractility and sarcomeric proteins from the early embryonic to the adult stage in the mouse heart. J Physiol 548: 493–505
Nakanishi T, Seguchi M, Tsuchiya T, Yasukouchi S, Takao A 1990 Effect of acidosis on intracellular pH and calcium concentration in the newborn and adult rabbit myocardium. Circ Res 67: 111–123
Fabiato A 1982 Calcium release in skinned cardiac cells: variations with species, tissues, and development. Fed Proc 41: 2238–2244
Fabiato A, Fabiato F 1979 Calculator programs for computing the composition of the solutions containing multiple metals and ligands used for experiments in skinned muscle cells. J Physiol (Paris) 75: 463–505
McAuliffe JJ, Gao LZ, Solaro RJ 1990 Changes in myofibrillar activation and troponin C Ca2+ binding associated with troponin T isoform switching in developing rabbit heart. Circ Res 66: 1204–1216
Potter JD, Sheng Z, Pan BS, Zhao J 1995 A direct regulatory role for troponin T and a dual role for troponin C in the Ca2+ regulation of muscle contraction. J Biol Chem 270: 2557–2562
Greig A, Hirschberg Y, Anderson PA, Hainsworth C, Malouf NN, Oakeley AE, Kay BK 1994 Molecular basis of cardiac troponin T isoform heterogeneity in rabbit heart. Circ Res 74: 41–47
Malouf NN, McMahon D, Oakeley AE, Anderson PA 1992 A cardiac troponin T epitope conserved across phyla. J Biol Chem 267: 9269–9274
Potter JD 1982 Preparation of troponin and its subunits. Methods Enzymol 85: 241–263
Pan BS, Johnson RG Jr 1996 Interaction of cardiotonic thiadiazinone derivatives with cardiac troponin C. J Biol Chem 271: 817–823
Guo X, Wattanapermpool J, Palmiter KA, Murphy AM, Solaro RJ 1994 Mutagenesis of cardiac troponin I. Role of the unique NH2-terminal peptide in myofilament activation. J Biol Chem 269: 15210–15216
Liao R, Wang CK, Cheung HC 1994 Coupling of calcium to the interaction of troponin I with troponin C from cardiac muscle. Biochemistry 33: 12729–12734
Taylor RB, Trimble C, Valdes JJ, Wayner MJ, Chambers JP 1992 Determination of free calcium. Brain Res Bull 29: 499–501
Nassar R, Malouf NN, Kelly MB, Oakeley AE, Anderson PA 1991 Force-pCa relation and troponin T isoforms of rabbit myocardium. Circ Res 69: 1470–1475
Nassar R, Malouf NN, Mao L, Rockman HA, Oakeley AE, Frye JR, Herlong JR, Sanders SP, Anderson PA 2005 cTnT1, a cardiac troponin T isoform, decreases myofilament tension and affects the left ventricular pressure waveform. Am J Physiol Heart Circ Physiol 288: H1147–H1156
Guth K, Potter JD 1987 Effect of rigor and cycling cross-bridges on the structure of troponin C and on the Ca2+ affinity of the Ca2+-specific regulatory sites in skinned rabbit psoas fibers. J Biol Chem 262: 13627–13635
Hatakenaka M, Ohtsuki I 1991 Replacement of three troponin components with cardiac troponin components within single glycerinated skeletal muscle fibers. Biochem Biophys Res Commun 181: 1022–1027
Anderson PA, Greig A, Mark TM, Malouf NN, Oakeley AE, Ungerleider RM, Allen PD, Kay BK 1995 Molecular basis of human cardiac troponin T isoforms expressed in the developing, adult, and failing heart. Circ Res 76: 681–686
Mitra R, Morad M 1985 A uniform enzymatic method for dissociation of myocytes from hearts and stomachs of vertebrates. Am J Physiol 249: H1056–H1060
Hamill OP, Marty A, Neher E, Sakmann B, Sigworth FJ 1981 Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflugers Arch 391: 85–100
Li Q, Altschuld RA, Stokes BT 1987 Quantitation of intracellular free calcium in single adult cardiomyocytes by fura-2 fluorescence microscopy: calibration of fura-2 ratios. Biochem Biophys Res Commun 147: 120–126
Grynkiewicz G, Poenie M, Tsien RY 1985 A new generation of Ca2+ indicators with greatly improved fluorescence properties. J Biol Chem 260: 3440–3450
Burtnick LD, McCubbin WD, Kay CM 1976 The isolation and characterization of the tropomyosin binding component (TN-T) of bovine cardiac troponin. Can J Biochem 54: 546–552
Putkey JA, Liu W, Lin X, Ahmed S, Zhang M, Potter JD, Kerrick WG 1997 Fluorescent probes attached to Cys 35 or Cys 84 in cardiac troponin C are differentially sensitive to Ca(2+)-dependent events in vitro and in situ. Biochemistry 36: 970–978
Anderson PA, Malouf NN, Oakeley AE, Pagani ED, Allen PD 1991 Troponin T isoform expression in humans. A comparison among normal and failing adult heart, fetal heart, and adult and fetal skeletal muscle. Circ Res 69: 1226–1233
Saba Z, Nassar R, Ungerleider RM, Oakeley AE, Anderson PA 1996 Cardiac troponin T isoform expression correlates with pathophysiological descriptors in patients who underwent corrective surgery for congenital heart disease. Circulation 94: 472–476
Townsend PJ, Barton PJ, Yacoub MH, Farza H 1995 Molecular cloning of human cardiac troponin T isoforms: expression in developing and failing heart. J Mol Cell Cardiol 27: 2223–2236
Gomes AV, Venkatraman G, Davis JP, Tikunova SB, Engel P, Solaro RJ, Potter JD 2004 Cardiac troponin T isoforms affect the Ca(2+) sensitivity of force development in the presence of slow skeletal troponin I: insights into the role of troponin T isoforms in the fetal heart. J Biol Chem 279: 49579–49587
Wattanapermpool J, Guo X, Solaro RJ 1995 The unique amino-terminal peptide of cardiac troponin I regulates myofibrillar activity only when it is phosphorylated. J Mol Cell Cardiol 27: 1383–1391
Reiser PJ, Westfall MV, Schiaffino S, Solaro RJ 1994 Tension production and thin-filament protein isoforms in developing rat myocardium. Am J Physiol 267: H1589–H1596
Metzger JM, Wahr PA, Michele DE, Albayya F, Westfall MV 1999 Effects of myosin heavy chain isoform switching on Ca2+-activated tension development in single adult cardiac myocytes. Circ Res 84: 1310–1317
Muthuchamy M, Grupp IL, Grupp G, O'Toole BA, Kier AB, Boivin GP, Neumann J, Wieczorek DF 1995 Molecular and physiological effects of overexpressing striated muscle beta-tropomyosin in the adult murine heart. J Biol Chem 270: 30593–30603
Arteaga GM, Palmiter KA, Leiden JM, Solaro RJ 2000 Attenuation of length dependence of calcium activation in myofilaments of transgenic mouse hearts expressing slow skeletal troponin I. J Physiol 526: 541–549
Godt RE, Fogaca RT, Nosek TM 1991 Changes in force and calcium sensitivity in the developing avian heart. Can J Physiol Pharmacol 69: 1692–1697
Huynh TV, Chen F, Wetzel GT, Friedman WF, Klitzner TS 1992 Developmental changes in membrane Ca2+ and K+ currents in fetal, neonatal, and adult rabbit ventricular myocytes. Circ Res 70: 508–515
Osaka T, Joyner RW 1991 Developmental changes in calcium currents of rabbit ventricular cells. Circ Res 68: 788–796
Wetzel GT, Chen F, Klitzner TS 1993 Ca2+ channel kinetics in acutely isolated fetal, neonatal, and adult rabbit cardiac myocytes. Circ Res 72: 1065–1074
Author information
Authors and Affiliations
Corresponding author
Additional information
This work was supported in part by NIH RO1 HL20749, RO1 HL42250, RO1 GM42501, and RO1 HL22231 and by grants from the Gustavius and Louise Pfeiffer Memorial Fund and the Children's Miracle Network.
Rights and permissions
About this article
Cite this article
McCall, S., Nassar, R., Malouf, N. et al. Development and Cardiac Contractility: Cardiac Troponin T Isoforms and Cytosolic Calcium in Rabbit. Pediatr Res 60, 276–281 (2006). https://doi.org/10.1203/01.pdr.0000233004.95404.1f
Received:
Accepted:
Issue date:
DOI: https://doi.org/10.1203/01.pdr.0000233004.95404.1f
This article is cited by
-
Reduced troponin I phosphorylation and increased Ca2+-dependent ATP-consumption in triton X-skinned fiber preparations from Gαq overexpressor mice
Molecular and Cellular Biochemistry (2008)
