Resting load and modulation of the myofilament Ca2+ sensitivity in rabbit cerebral arteries.
The effect of preload on myofilament Ca2+ sensitivity was examined using alpha-toxin permeabilization and fura-2 fluorometry in rabbit cerebral arteries. The [Ca2+]i-force curves shifted leftward at a high preload, with a decrease in median effective concentration of Ca2+ in the permeabilized artery. In the fura-2-loaded artery, the preload modulated the force without affecting [Ca2+]i levels during K+ depolarization, and a high preload moved the [Ca2+]i-force curve upward and to the left. It is thus concluded that the preload regulates the Ca2+ sensitivity of the myofilament and, therefore, may play a role in the regulation of cerebral arterial tonus and blood flow.
Chen
X
X
Division of Molecular Cardiology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Miyagi
Y
Y
Nishimura
J
J
Kobayashi
S
S
Fukui
M
M
Kanaide
H
H
D008841:Actin Cytoskeleton / Q000187:drug effects*; D000818:Animals; D001488:Basilar Artery / Q000187:drug effects / Q000648:ultrastructure; D002118:Calcium / Q000494:pharmacology*; D002536:Cerebral Arteries / Q000502:physiology* / Q000648:ultrastructure; D002560:Cerebrovascular Circulation; D004351:Drug Resistance; D004423:Ear / Q000098:blood supply; D005456:Fluorescent Dyes; D005470:Fluorometry; D016257:Fura-2; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D011817:Rabbits; D013314:Stress, Mechanical; D014661:Vasoconstriction / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology*; D014666:Vasomotor System / Q000187:drug effects*
D005456:Fluorescent Dyes; D014662:Vasoconstrictor Agents; D002118:Calcium; D016257:Fura-2