ISSN:
1432-2013
Keywords:
Smooth muscle regulation
;
Calcium activation
;
c-AMP
;
c-AMP dependent protein kinase
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract Smooth muscle from guinea pig taenia coli was chemically skinned with Triton X-100 and stored in ATP-salt solution containing 50% glycerol at −20°C. Fibre bundles were relaxed at Ca2+-concentrations below 10−7 M, but contracted at 10−6 M Ca2+. The isometric tension developed could be partly relaxed by the addition of c-AMP (in the presence of NaF), and it could also be inhibited following preincubation with the catalytic subunit of c-AMP dependent protein kinase. The inhibitory effect was much more pronounced at intermediate Ca2+-concentrations (e.g. 10−6) than at concentrations producing a maximum contraction, suggesting that Ca-sensitivity had been lowered. Sodium fluoride which was required to potentiate the c-AMP effects was found to have a slight relaxing effect per se. The c-AMP effect may be mediated through activation of cyclic AMP-dependent kinase, producing phosphorylation of the myosin light chain kinase which, according to adelstein et al. (1978), may result in a net dephosphorylation of the myosin light chains and a concomittant inhibition of the contractile response.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00590207
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