Relationship between cytosolic Ca2+ level and contractile tension in canine basilar artery of chronic vasospasm.
In order to study the role of the Ca2+/calmodulin/myosin light chain kinase system in the development of chronic vasospasm caused by subarachnoid hemorrhage, the cytosolic Ca2+ level ([Ca2+]i), measured with fura-2, a fluorescent Ca2+ indicator, and contractile tension were measured simultaneously, and their quantitative correlation was examined in basilar arterial tissue obtained from the canine "two-hemorrhage" model. Sixteen adult mongrel dogs were divided into two groups, control (n = 8) and vasospasm (n = 8), and were killed 7 days after the first experimental subarachnoid hemorrhage. In basilar arterial tissue loaded with fura-2, 1) [Ca2+]i in the resting condition was not significantly different between the two groups; 2) the increment in [Ca2+]i induced by 40 mmol/L K+ stimulation was significantly smaller in vasospastic tissue (P < 0.01); and 3) 40 mmol/L K(+)-induced tension development per cross-sectional area for a fixed increment in [Ca2+]i was significantly greater in vasospastic tissue (P < 0.01). In tissue not loaded with fura-2, active myogenic tone, which was tentatively represented by the ratio of tonus relaxed with 10(-4) mol/L papaverine to initial resting tone, was significantly greater in vasospastic tissue (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Yamada
T
T
Department of Surgical Neurology, Jichi Medical School, Tochigi, Japan.
Tanaka
Y
Y
Fujimoto
K
K
Nakahara
N
N
Shinoda
S
S
Masuzawa
T
T
D000818:Animals; D001488:Basilar Artery / Q000503:physiopathology; D002118:Calcium / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism*; D004285:Dogs; D005260:Female; D016257:Fura-2; D002546:Ischemic Attack, Transient / Q000503:physiopathology*; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology*; D009129:Muscle Tonus / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000503:physiopathology*; D011188:Potassium / Q000502:physiology; D013345:Subarachnoid Hemorrhage / Q000503:physiopathology
D011188:Potassium; D002118:Calcium; D016257:Fura-2