Abstract

The aim is to identify and study the mechanisms by which volatile anesthetics depress contractility of heart muscle in vitro. The approach will use technology that allows one to evaluate simultaneously variables of mechanical function (length, force, velocity, elastic stiffness and time) and changes in intracellular calcium concentration detected with the Ca2+-sensitive bioluminescent protein aequorin in intact living ventricular cardiac muscle. In the first project the hypothesis will be tested that volatile anesthetics halothane, enflurane and isoflurane do not alter (1) the luminescent reaction of aequorin with Ca2+ ions, i.e., quantum yield and Ca2+ sensitivity of the Ca2+-regulated bioluminescent protein aequorin, and the apparent association constants of various metal chelators (EGTA, EDTA, CDTA) for Ca2+. This information will serve to quantify light signals from aequorin into intracellular calcium concentrations in living heart muscle. Three detailed studies of the intracellular free calcium concentration transient in rhythmically contracting heart muscle will allow one to pinpoint effects of each of the volatile agents on (1) release and entry of Ca2+ in the cytoplasm, (2) uptake of Ca2+ into intracellular storage sites, (3) apparent sensitivity of the contractile proteins for Ca2+, and (4) influx of Ca2+ through the cardiac sarcolemmal membrane. This approach has the advantage that it assesses the relative contribution of several cellular components involved in excitation-contraction coupling in an unperturbed, intact muscle. In a fifth study, instantaneous elastic stiffness will be measured throughout contraction and relaxation of heart muscle in the absence and presence of anesthetic agents. The information will shed light on the time course of onset and decay of instantaneous force potential of heart muscle in the presence of volatile anesthetics. The relative dissociation in time of the decline of the calcium transient and of elastic stiffness will provide corroborative information of the effects of anesthetics on the detachment of crossbridges.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM036365-03
Application #
3290187
Study Section
Surgery, Anesthesiology and Trauma Study Section (SAT)
Project Start
1986-12-01
Project End
1989-11-30
Budget Start
1988-12-01
Budget End
1989-11-30
Support Year
3
Fiscal Year
1989
Total Cost
Indirect Cost

  Institution

Name
Mayo Clinic, Rochester
Department
Type
DUNS #
City
Rochester
State
MN
Country
United States
Zip Code
55905

  Publications

Pakkiri, Leroy S; Wolucka, Beata A; Lubert, Eric J et al. (2004) Structural and topological studies on the lipid-mediated assembly of a membrane-associated lipomannan in Micrococcus luteus. Glycobiology 14:73-81
Breukelmann, Dirk; Housmans, Philippe R (2003) Equilibrium titration of protein-ligand binding affinity in the presence of volatile reagents--a semiautomated approach. Anal Biochem 313:86-8
Rick, Paul D; Barr, Kathleen; Sankaran, Krishnan et al. (2003) Evidence that the wzxE gene of Escherichia coli K-12 encodes a protein involved in the transbilayer movement of a trisaccharide-lipid intermediate in the assembly of enterobacterial common antigen. J Biol Chem 278:16534-42
Wu, Xiaohua; Rush, Jeffrey S; Karaoglu, Denise et al. (2003) Deficiency of UDP-GlcNAc:Dolichol Phosphate N-Acetylglucosamine-1 Phosphate Transferase (DPAGT1) causes a novel congenital disorder of Glycosylation Type Ij. Hum Mutat 22:144-50
Bartunek, Anna E; Claes, Victor A; Housmans, Philippe R (2002) Effects of volatile anesthetics on elastic stiffness in isometrically contracting ferret ventricular myocardium. J Appl Physiol 92:2491-500
Lang, Rosalyn; Gomes, Aldrin V; Zhao, Jiaju et al. (2002) Functional analysis of a troponin I (R145G) mutation associated with familial hypertrophic cardiomyopathy. J Biol Chem 277:11670-8
Bartunek, A E; Claes, V A; Housmans, P R (2001) Effects of volatile anesthetics on stiffness of mammalian ventricular muscle. J Appl Physiol 91:1563-73
Knollmann, B C; Blatt, S A; Horton, K et al. (2001) Inotropic stimulation induces cardiac dysfunction in transgenic mice expressing a troponin T (I79N) mutation linked to familial hypertrophic cardiomyopathy. J Biol Chem 276:10039-48
Miller, T; Szczesna, D; Housmans, P R et al. (2001) Abnormal contractile function in transgenic mice expressing a familial hypertrophic cardiomyopathy-linked troponin T (I79N) mutation. J Biol Chem 276:3743-55
Hannon, J D; Cody, M J; Housmans, P R (2001) Effects of isoflurane on intracellular calcium and myocardial crossbridge kinetics in tetanized papillary muscles. Anesthesiology 94:856-61

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