Agonist and membrane depolarization induced activation of map
kinase in the swine carotid artery.
Katoch, Surender S., and Robert S. Moreland.
Bockus Research Institute, Graduate Hospital, 415 S. 19th Street,
Philadelphia, PA 19146
APStracts 2:0033H, 1995.
Caldesmon phosphorylation has been proposed to be involved in
regulation of smooth muscle contraction. Mitogen-activated protein
(MAP) kinase has been suggested to be the caldesmon kinase;
stimulation induced MAP kinase activation in intact vascular smooth
muscle however has not been demonstrated. We measured temporal
profiles of MAP kinase activation in response to histamine
stimulation and membrane depolarization in intact swine carotid
artery. Phosphotyrosine levels of 42 and 44 kDa MAP kinases were
elevated during contraction in response to histamine or KCl. The
temporal profile of MAP kinase activation/inactivation was similar to
that for contraction/relaxation of the vascular tissue in response to
KCl or histamine stimulation. MAP kinase activated during contractile
stimulation phosphorylates caldesmon with a specific activity
significantly greater than that for myelin basic protein95-98. We
propose that MAP kinase is activated in response to all forms of
contractile stimulation. We also suggest that activated MAP kinase
phosphorylates and disinhibits the effects of caldesmon on actin
-myosin interactions. This disinhibition allows an inherent level of
myosin ATPase activity to be expressed.
Received 21 September 1994; accepted in final form 24 January
1995.
APS Manuscript Number H850-4.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 24 February 1995.