Methylprednisolone enhances contraction of porcine femoral head epiphyseal arteries

The pathomechanism of steroid-induced femoral head necrosis is thought to be disturbed femoral head blood flow. We hypothesize that methylprednisolone increases vasocontraction of femoral head epiphyseal arteries, thereby reducing femoral head blood flow. Nine immature female domestic pigs were randomly selected from a group of 18 to receive 24-hour methylprednisolone treatment, whereas the nine remaining pigs received the placebo control in a blinded fashion. After sacrifice, lateral epiphyseal artery segments from the femoral heads were mounted as ring preparations on a small vessel myograph. Isometric active tension was measured in relation to cumulating doses of the vasoconstrictors noradrenaline and endothelin-1, and the vasodilator bradykinin. Vasocontraction to noradrenaline was not altered by methylprednisolone. Bradykinin elicited a concentration-dependent vasodilation which was lower in the corticosteroid-treated vessels. Vasoconstriction to endothelin-1 was stronger in the corticosteroid-treated vessels. Our data indicate that methylprednisolone enhances contraction of femoral head lateral epiphyseal arteries and may decrease femoral head blood flow. To our knowledge, this pathomechanic factor in femoral head necrosis has not been described before.