Preferential Orientation of Centrioles toward the Heart in Endothelial Cells of Major Blood Vessels is Reestablished after Reversal of a Segment

The distribution of centrioles was examined in porcine and rabbit vascular endothelial cells fixed in situ and prepared en face for immunofluorescent staining with rabbit sera that specifically stain these organelles. In endothelial cells lining the major blood vessels of the pig, the centrioles are preferentially located on the heart side of the nucleus regardless of the direction of blood flow. A similar distribution is seen in the inferior vena cava of the rabbit but not in the rabbit aorta. In the major vessels of the pig and in the rabbit inferior vena cava, 60%-80% of the endothelial cells have their centrioles located on the side of the nucleus toward the heart, 10%-20% have them on the side away from the heart, and 7%-15% have them in a central position along the side of the nucleus. To determine whether this preferential orientation is reestablished, microvascular surgical techniques were used to reverse a 3-cm segment of the inferior vena cava between the left renal vein and the common iliac veins of the rabbit. Within 1 week of the reversal, some of the centrioles had migrated from the end away from the heart to a more central position. During the following weeks, an increasing number of endothelial cells had their centrioles located on the heart side of the nucleus; after 12 weeks, values similar to those in the nonreversed inferior vena cava were reached in the reversed segment. The demonstration that the preferential orientation of centrioles on the heart side of the nucleus is reestablished after reversal of a segment suggests that the observed polarity is important for normal functioning of vascular endothelium.