title: Protein phosphorylation during the contraction-relaxation-contraction cycle of arterial smooth muscle.
abstract: Porcine carotid arterial muscles were labeled with 32P and then subjected to a resting-contraction-relaxation-contraction cycle. Four different agents were used for contraction: KCl, histamine, norepinephrine, and phorbol dibutyrate. To relax the contracted muscles, they were washed with physiological salt solution. Changes in the [32P]phosphate content of four different proteins--myosin light chain, a 28-kDa cytosolic protein, desmin, and caldesmon--were followed. In a short contraction-relaxation-contraction cycle lasting minutes, induced by K+, histamine, or norepinephrine, only the light chain underwent a phosphorylation-dephosphorylation-rephosphorylation without concomitant cyclic phosphorylation of the 28-kDa protein, desmin, or caldesmon. In a contraction-relaxation-contraction cycle of long duration, 60-min contractions with K+, histamine, or norepinephrine, cyclic phosphorylation of both the light chain and desmin was observed. With 60-min phorbol dibutyrate stimulation, in the long contraction-relaxation-contraction cycle, the phosphorylations of the light chain, desmin, and caldesmon were cycling. It is concluded that under physiological conditions, light-chain phosphorylation initiates both short and sustained arterial contraction. Desmin phosphorylation is likely to be involved in force maintenance during sustained contraction.
authors.affiliation: Department of Biochemistry, College of Medicine, University of Illinois, Chicago 60612.
authors.forename: M
authors.initials: M
authors.lastname: Bárány
authors.forename: E
authors.initials: E
authors.lastname: Polyák
authors.forename: K
authors.initials: K
authors.lastname: Bárány
mesh_terms: D000818:Animals; D001345:Autoradiography; D002148:Calmodulin-Binding Proteins / Q000378:metabolism; D002339:Carotid Arteries / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D003893:Desmin / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D006632:Histamine / Q000494:pharmacology; D007525:Isoelectric Focusing; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009124:Muscle Proteins / Q000302:isolation & purification / Q000378:metabolism*; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D009218:Myosins / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D010750:Phosphoproteins / Q000302:isolation & purification / Q000378:metabolism*; D010761:Phosphorus Radioisotopes; D010766:Phosphorylation; D013552:Swine
chemical_list: D002148:Calmodulin-Binding Proteins; D003893:Desmin; D009124:Muscle Proteins; D010710:Phosphates; D010750:Phosphoproteins; D010761:Phosphorus Radioisotopes; D006632:Histamine; D009218:Myosins