The time course of myosin light-chain phosphorylation in blood-induced vasospasm.
The phosphorylation of an M(r) 20,000 myosin light chain (MLC20) promotes the generation of contractile force through actin-myosin adenosine triphosphatase in most agonist-mediated vascular smooth muscle cell contraction. However, the role of calcium-mediated contractile processes in sustained arterial narrowing after subarachnoid hemorrhage remains unknown. In a femoral artery model of vasospasm, whole blood was applied to arteries in 54 rats for periods of 2 to 10 days; the contralateral artery treated with platelet-rich plasma served as matched control. During the early stage of vasospasm (Days 2-5), in the media of arteries exposed to blood, MLC20 phosphorylation (including diphosphorylated forms) increased significantly (30-38%; P < 0.05); total medial MLC20 during this interval was comparable to that in controls. After 5 days, however, total MLC20 decreased markedly (> 90%; P < 0.01) compared with controls; phosphorylated MLC20 was undetectable during this interval. MLC20-mediated contractile processes may be prominent in the early stages of arterial narrowing after subarachnoid hemorrhage; later stages are associated with the loss of MLC20 and the possible persistence of arterial narrowing by other mechanisms.
Harada
T
T
Department of Neurological Surgery, University of Washington, Seattle, USA.
Seto
M
M
Sasaki
Y
Y
London
S
S
Luo
Z
Z
Mayberg
M
M
D000818:Animals; D002118:Calcium / Q000502:physiology; D002147:Calmodulin / Q000502:physiology; D004195:Disease Models, Animal; D002546:Ischemic Attack, Transient / Q000503:physiopathology*; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000503:physiopathology; D009219:Myosin-Light-Chain Kinase / Q000502:physiology; D009218:Myosins / Q000502:physiology*; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013345:Subarachnoid Hemorrhage / Q000503:physiopathology*; D014655:Vascular Resistance / Q000502:physiology
D002147:Calmodulin; D009219:Myosin-Light-Chain Kinase; D009218:Myosins; D002118:Calcium