Penetrating, intracerebral arterioles from rat were isolated, cannulated, and studied in vitro. Vessel wall elements were found to consist of an endothelial cell layer, one smooth muscle cell layer, and a thin adventitial layer or leptomeningeal sheath. Smooth muscle cell nuclei were oriented perpendicular to the vessel's longitudinal axis; endothelial cell nuclei were parallel to the axis. Mean vessel diameter with the smooth muscle inactivated (passive diameter) was 36.7 ± 1.6 (SE) μm. Spontaneous smooth muscle tone developed at 37°C and reduced vessel diameter to 70 ± 4% of passive diameter. Vessels were activated by the extraluminal application of 140 mM KCl solution at pH 8.00, which produced a transient contraction that decayed within 30 s to a steady contraction of somewhat less intensity. Changes in intravascular pressure were used to alter wall tension of the vessels. Tension in the vessel wall was computed, and length-tension curves for the arteriolar smooth muscle were approximated. Length-tension relationships similar to those seen in other smooth-muscle preparations were found with maximal estimated force development of 1.29 x 10-5 N.m-2. Alterations of bath pH caused changes in vessel diameter that were inversely related to extraluminal pH and varied by approximately 77% in the range from pH 6.85 to 8.00. Adenosine dilated vessels to 140 ± 6% of control diameter at a concentration of 10-5 M. The mechanical characteristics and the reactivity to H+, K+, and adenosine of these vessels were quantitatively consistent with in vitro data from larger cerebral vessels and in vivo data from pial arteries.
|Journal||American Journal of Physiology - Heart and Circulatory Physiology|
|State||Published - Jan 1 1982|