MORPHOLOGICAL EFFECT OF EPINEPHRINE AND I NSULIN ON CORTICAL BONE CAPILLARIES AFTER RECEPTOR BLOCKADE - A FUNCTIONAL TRANSMISSION ELECTRON-MICROSCOPIC ANALYSIS

In three groups of six mice each, the alpha- and beta-receptors were b locked by phentolamine and propranolol. The mice in the three groups t hen received an intravenous bolus injection of saline solution, epinep hrine, and insulin, respectively. Cortical bone capillaries from the t ibia diaphysis were submitted to transmission electron microscopy (TEM ). The lumen and endothelium were measured and the results compared. S ignificant changes were only noted in the endothelium after the admini stration of insulin. These findings suggest that there are also insuli n receptors in bone. Furthermore, they support previous findings in si milar studies with epinephrine.