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Polyamines inhibit ...
Polyamines inhibit myosin phosphatase and increase LC20 phosphorylation and force in smooth muscle
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- Swärd, Karl (author)
- Lund University,Lunds universitet,Kärlfysiologi,Forskargrupper vid Lunds universitet,Vascular Physiology,Lund University Research Groups
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- Pato, M D (author)
- University of Saskatchewan
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- Nilsson, Bengt-Olof (author)
- Lund University,Lunds universitet,Kärlfysiologi,Forskargrupper vid Lunds universitet,Vascular Physiology,Lund University Research Groups
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- Nordström, Ina (author)
- Lund University,Lunds universitet,Kärlfysiologi,Forskargrupper vid Lunds universitet,Vascular Physiology,Lund University Research Groups
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- Hellstrand, Per (author)
- Lund University,Lunds universitet,Kärlfysiologi,Forskargrupper vid Lunds universitet,Vascular Physiology,Lund University Research Groups
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(creator_code:org_t)
- 1995
- 1995
- English.
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In: American Journal of Physiology: Cell Physiology. - 1522-1563. ; 269:3, s. 563-571
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Abstract
Subject headings
Close
- The increase in Ca(2+)-activated force caused by polyamines in beta-escin-permeabilized guinda pig ileum is shown to be associated with increased myosin 20-kDa light chain (LC20) phosphorylation and shortening velocity. Myosin LC20 dephosphorylation with arrested kinase activity was slower in the presence of 1 mM spermine. Smooth muscle phosphatases (SMP-I, -II, -III, and -IV) isolated from turkey gizzard are all active against phosphorylated LC20, but only SMP-III and -IV dephosphorylate heavy meromyosin (HMM). Spermine inhibited SMP-III activity toward LC20 but stimulated HMM dephosphorylation, whereas SMP-IV was inhibited with both substrates. In contrast, SMP-I and -II were stimulated by spermine. The relative effects of different polyamines correlated with an increasing number of positive charges. Spermine did not affect binding of SMP-IV to myosin and did not dissociate any of the subunits of the enzyme. Incubation of permeabilized strips with SMP-IV resulted in attenuated responses to Ca2+, an effect that was opposed by spermine and abolished by microcystin-LR. We conclude that spermine selectively inhibits myosin phosphatase activity and suggest that polyamines function as endogenous myosin phosphatase inhibitors.
Subject headings
- MEDICIN OCH HÄLSOVETENSKAP -- Medicinska och farmaceutiska grundvetenskaper -- Fysiologi (hsv//swe)
- MEDICAL AND HEALTH SCIENCES -- Basic Medicine -- Physiology (hsv//eng)
Keyword
- Animals
- Female
- Gizzard
- Guinea Pigs
- Ileum
- In Vitro Techniques
- Muscle Contraction
- Muscle, Smooth
- Myosin Light Chains
- Myosin-Light-Chain Kinase
- Myosin-Light-Chain Phosphatase
- Permeability
- Phosphoprotein Phosphatases
- Phosphoric Monoester Hydrolases
- Phosphorylation
- Polyamines
- Spermine
- Turkeys
Publication and Content Type
- art (subject category)
- ref (subject category)
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