In human and animal brain microvessels
beta-adrenergic receptors have been identified which are suggested to subserve the regulation of capillary function in both physiological and pathological conditions.
Brain tumors are supplied by vessels that differ from those supplying normal cerebral tissue in various structural and functional parameters. In order to study the characteristics of
brain tumor microcirculation, we have investigated the presence of
beta-adrenergic receptors in capillaries isolated from different types of
neoplasms using the specific radioligand 125I-iodocyanopindolol (
ICYP). The microvessels were isolated and prepared by
albumin flotation and glass bead filtration from normal and pathological tissues. No
ICYP-specific binding was detected in the microvessels of
tumors of glial origin, while capillaries obtained from
meningiomas and
neurinomas showed, like the normal brain, a specific binding of the radioligand. The data indicate that the regulation of capillary function in glial
tumors differs from that of normal cerebral tissue and extraparenchymal
tumors, thus indicating an impaired control of the vascular permeability.