The effects of MgADP on cross‐bridge kinetics: a laser flash photolysis study of guinea‐pig smooth muscle.

@article{Nishiye1993TheEO,
  title={The effects of MgADP on cross‐bridge kinetics: a laser flash photolysis study of guinea‐pig smooth muscle.},
  author={E. Nishiye and A. Somlyo and K. T{\"o}r{\"o}k},
  journal={The Journal of Physiology},
  year={1993},
  volume={460}
}
1. The effects of MgADP on cross‐bridge kinetics were investigated using laser flash photolysis of caged ATP (P3‐1(2‐nitrophenyl) ethyladenosine 5'‐triphosphate), in guinea‐pig portal vein smooth muscle permeabilized with Staphylococcus aureus alpha‐toxin. Isometric tension and in‐phase stiffness transitions from rigor state were monitored upon photolysis of caged ATP. The estimated concentration of ATP released from caged ATP by high‐pressure liquid chromatography (HPLC) was 1.3 mM. 2. The… Expand
Flash photolysis studies of relaxation and cross-bridge detachment: higher sensitivity of tonic than phasic smooth muscle to MgADP
TLDR
The marked slowing by MgADP of the late phases of relaxation from rigor in femoral artery suggests that in tonic smooth muscle the nucleotide affects not only rigor bridges, but also additional state(s) of cooperatively cycling cross-bridges. Expand
Effects of inorganic phosphate on cross‐bridge kinetics at different activation levels in skinned guinea‐pig smooth muscle.
TLDR
It is proposed that shortening velocity is rate limited by cross‐bridge states, reached early after attachment, which impose a mechanical resistance to shortening under isotonic or isometric conditions in maximally activated smooth muscle fibres. Expand
Time-resolved measurements of phosphate release by cycling cross-bridges in portal vein smooth muscle.
TLDR
It is concluded that the transition from fast to slow ATPase rates reflects the properties and forces directly acting on cross-bridges, rather than the result of a time-dependent decrease in activation (MLC20 phosphorylation) occurring in intact smooth muscle. Expand
Mechanical study of rat soleus muscle using caged ATP and X‐ray diffraction: high ADP affinity of slow cross‐bridges
TLDR
It is concluded that, despite the tight ADP binding of the soleus cross‐bridge, its isometric reaction is not rate limited by the ‘off’ rate of ADP. Expand
Regulation of the cross-bridge cycle: the effects of MgADP, LC17 isoforms and telokin.
TLDR
The results suggest that telokin contributes to cAMP and/or cGMP kinase-mediated Ca(2+)-desensitization of phasic smooth muscles. Expand
Kinetics of Prephosphorylation Reactions and Myosin Light Chain Phosphorylation in Smooth Muscle
The pre-myosin light chain (MLC20) phosphorylation components of the lag phase (td) of contractile activation were determined in permeabilized smooth muscles activated by photolytic release of ATPExpand
Photolytic release of MgADP reduces rigor force in smooth muscle.
TLDR
The effect of additions of MgADP to rigor cross-bridges could result from rotation of the lever arm of smooth muscle myosin, but this need not imply that ADP-release is a significant force-producing step of the physiological cross-bridge cycle. Expand
Smooth muscle myosin: regulation and properties.
  • A. Somlyo, A. Khromov, +6 authors A. Somlyo
  • Chemistry, Medicine
  • Philosophical transactions of the Royal Society of London. Series B, Biological sciences
  • 2004
TLDR
ADP release in phasic and tonic smooth muscles is a regulated step with strain- and dephosphorylation-dependence and may limit the ATPase rate, according to the rates of ADP release from rigor cross-bridges and the steady-state Pi release from cycling isometric cross- bridges. Expand
The ADP release step of the smooth muscle cross-bridge cycle is not directly associated with force generation.
TLDR
The results suggest that the axial motion of smooth muscle S1 bound to actin, upon dissociation of MgADP, is not associated with force generation, which may be explained if geometrical constraints of the intact contractile filament array alter the motions of the myosin heads. Expand
Cross-Bridge Cycle in Phasic and Tonic Smooth Muscle
Comparison of the cross-bridge cycle and its regulation in phasic and tonic smooth muscles reveals the following: (1) ATP binding and the detachment of cross-bridges by ATP is fast and notExpand
...
1
2
3
4
5
...

References

SHOWING 1-10 OF 48 REFERENCES
Cross‐bridge kinetics in the presence of MgADP investigated by photolysis of caged ATP in rabbit psoas muscle fibres.
TLDR
The results suggest that phases bt and ct are complex processes involving ADP dissociation, cross‐bridge reattachment and co‐operative detachment involving filament sliding and the Ca(2+)‐regulatory system. Expand
Cross-bridge kinetics, cooperativity, and negatively strained cross- bridges in vertebrate smooth muscle. A laser-flash photolysis study
TLDR
Under physiological conditions, in non-thiophosphorylated muscles, light-chain phosphorylation, rather than intrinsic properties of the actomyosin cross-bridges, limits the rate of force development, which may contribute to force maintenance at low energy cost and low cross-bridge cycling rates in smooth muscle. Expand
Kinetics of contraction initiated by flash photolysis of caged adenosine triphosphate in tonic and phasic smooth muscles
TLDR
The results suggest that both the contractile machinery and the regulatory system are slower in the tonic than in the phasic smooth muscles. Expand
Relaxation of rabbit psoas muscle fibres from rigor by photochemical generation of adenosine‐5'‐triphosphate.
TLDR
The results indicate that ATP binding and cross‐bridge detachment from the nucleotide‐free intermediate of thecross‐bridge cycle are rapid compared to the cross‐ bridge cycling rate. Expand
Flash photolysis studies of excitation-contraction coupling, regulation, and contraction in smooth muscle.
TLDR
It is suggested that the major portion of the delay between agonist-receptor interaction and contraction is due to activation of phospholipase C and InsP3 production, and in muscles in which the myosin light chains are maintained in a phosphorylated state during rigor, photolysis of caged ATP initiates contractions with a short delay. Expand
Inorganic phosphate regulates the contraction‐relaxation cycle in skinned muscles of the rabbit mesenteric artery.
TLDR
Pi may accelerate the detachment of cross‐bridges between the contractile proteins and the relaxation is markedly facilitated, however, the site of action of Pi may differ from that of MgATP. Expand
The ATPase mechanism of skeletal and smooth muscle acto-subfragment 1.
TLDR
The proposed mechanism does not exclude the possibility of additional ATP or product intermediate states, but the properties of such states cannot be deduced from the kinetic evidence. Expand
The steady state intermediate of scallop smooth muscle myosin ATPase and effect of light chain phosphorylation. A molecular mechanism for catch contraction.
TLDR
The results suggest that the main intermediate at the steady state of opaque myosin ATPase is converted depending on the concentration of Ca2+, from EPADP in the presence ofCa2+ to EADP on the phosphorylation of RLC-a on theosphorylated light chain-a. Expand
Influence of ATP, ADP and AMPPNP on the energetics of contraction in skinned smooth muscle.
TLDR
The influence of MgATP and MgADP on smooth muscle contraction suggest that the concentrations of substrate and products, at the level of the contractile proteins, may constitute important regulatory factors in vivo under conditions, such as hypoxia and ischemia, associated with impaired cellular energy supply. Expand
Irreversible thiophosphorylation and activation of tension in functionally skinned rabbit ileum strips by [35S]ATP gamma S.
TLDR
Ca2+-sensitive, reversible activated tension and reversible 32P-labeling of the LC20 are consistent with a currently proposed model of Ca2+ control of smooth muscle contraction involving a myosin light chain kinase-phosphatase system. Expand
...
1
2
3
4
5
...