TY - JOUR
T1 - Cholinergic vasodilation of intracerebral arterioles in rats
AU - Dacey, R. G.
AU - Bassett, J. E.
PY - 1987
Y1 - 1987
N2 - Much morphological and physiological evidence indicates that cholinergic mechanisms play a significant role in the control of cerebral blood flow. Despite in situ data suggesting that an intrinsic cholinergic mechanism produces vasodilation in the intracerebral microcirculation, there is no direct information on the effect of acetylcholine (ACh) on intracerebral arterioles. We investigated cholinergic mechanisms in isolated perfused intracerebral arterioles from pentobarbital sodium-anesthetized Sprague-Dawley rats. In arterioles with resting diameters of 46.8 ± 6.6 μm (mean ± SE) ACh produced no significant dilation at pH 7.30. At pH 7.60, however, a significant dose-dependent dilation to a maximum of 119.0 ± 1.0% of control diameter was observed. Carbachol, a long-acting cholinergic agonist, similarly failed to dilate vessels at pH 7.30 but significantly dilated vessels at pH 7.60. Prostaglandin F(2a) produced a maximum contraction to 68.3 ± 2.7% of control diameter (n = 8). ACh at concentrations of 10-4 and 2 x 10-4 M induced a significant dilation of this prostaglandin-induced contraction. In vessels similarly preconstricted with serotonin, 10-4 M ACh produced significant dilation. Atropine, having no effect on vessel diameter when administered alone, blocked cholinergic vasodilation of intracerebral arterioles at pH 7.60. Attempts at endothelial removal, although successful in eliminating endothelial cells from the preparation, significantly impaired smooth muscle contractility. ACh has no significant effect on the spontaneous cerebrovascular tone in this preparation, but in vessels preconstricted by a variety of means it produced vasodilation mediated by atropine sensitive receptors.
AB - Much morphological and physiological evidence indicates that cholinergic mechanisms play a significant role in the control of cerebral blood flow. Despite in situ data suggesting that an intrinsic cholinergic mechanism produces vasodilation in the intracerebral microcirculation, there is no direct information on the effect of acetylcholine (ACh) on intracerebral arterioles. We investigated cholinergic mechanisms in isolated perfused intracerebral arterioles from pentobarbital sodium-anesthetized Sprague-Dawley rats. In arterioles with resting diameters of 46.8 ± 6.6 μm (mean ± SE) ACh produced no significant dilation at pH 7.30. At pH 7.60, however, a significant dose-dependent dilation to a maximum of 119.0 ± 1.0% of control diameter was observed. Carbachol, a long-acting cholinergic agonist, similarly failed to dilate vessels at pH 7.30 but significantly dilated vessels at pH 7.60. Prostaglandin F(2a) produced a maximum contraction to 68.3 ± 2.7% of control diameter (n = 8). ACh at concentrations of 10-4 and 2 x 10-4 M induced a significant dilation of this prostaglandin-induced contraction. In vessels similarly preconstricted with serotonin, 10-4 M ACh produced significant dilation. Atropine, having no effect on vessel diameter when administered alone, blocked cholinergic vasodilation of intracerebral arterioles at pH 7.60. Attempts at endothelial removal, although successful in eliminating endothelial cells from the preparation, significantly impaired smooth muscle contractility. ACh has no significant effect on the spontaneous cerebrovascular tone in this preparation, but in vessels preconstricted by a variety of means it produced vasodilation mediated by atropine sensitive receptors.
UR - http://www.scopus.com/inward/record.url?scp=0023514360&partnerID=8YFLogxK
M3 - Article
C2 - 3479909
AN - SCOPUS:0023514360
VL - 253
SP - 22/5
JO - American Journal of Physiology - Heart and Circulatory Physiology
JF - American Journal of Physiology - Heart and Circulatory Physiology
SN - 0363-6135
IS - 5
ER -