The authors investigated selective intra- and extraluminal effects of endothelin (ET) on perfused basilar and extracranial arteries and also studied the interaction between ET and extraluminal oxyhemoglobin (oxyHb). The basilar, mesenteric, and femoral arteries were isolated from 23 Japanese White rabbits. After isolation of the intra- and extraluminal sides of the preparation, 3 x 10(-10) to 3 x 10(-8) mol/L of ET was administered intra- or extraluminally. After extraluminal pretreatment with 10(-5) mol/L oxyHb, 10(-5) mol/L N(G)-monomethyl-L-arginine (L-NMMA), or 10(-6) mol/L indomethacin, 10(-10) to 10(-8) mol/L of ET was administered intra- or extraluminally. Arterial contraction was evaluated by measuring the increase in the perfusion pressure gradient with a differential pressure gauge. Both intra- and extraluminal ET (10(-9) to 3 x 10(-8) mol/L) showed potent and dose-dependent vasoconstricting effects on basilar arteries (p < 0.01). The effect of ET on the basilar arteries was significantly greater than on the femoral or mesenteric arteries (both p < 0.01). The effect of intraluminal ET was enhanced by extraluminal oxyHb (p < 0.05) and L-NMMA (p < 0.01), but not by extraluminal indomethacin. Extraluminal oxyHb did not potentiate the contraction induced by extraluminal ET. These results indicate that the sensitivity of the basilar artery to intraluminal ET is greater than that of the femoral or mesenteric artery. Endothelin may act as a potent vasoconstrictor intra- as well as extraluminally under conditions such as subarachnoid hemorrhage in which oxyHb is present in the extraluminal space and endothelium-derived relaxing factors are inhibited.

The term "infantile myofibromatosis" was coined in 1981 to describe a rare type of soft-tissue tumor in infants. Solitary lesions are usual, but extremely rare in the skull. An infantile case involving a lesion in the left parietal bone is described. The patient was a 6-month-old girl admitted with a mass measuring 2 x 2 cm in the left parietal region. Skull x-rays showed an osteolytic lesion with a sclerotic margin in the parietal bone. Computed tomographic (CT) scans revealed a low-density mass with homogeneous enhancement. The tumor adhered to the dura and had destroyed the left parietal bone. Histological examination disclosed spindle-shaped cells arranged in short bundles and abundant vasculature. Phosphotungstic acid hematoxylin staining revealed longitudinal fibrils resembling myofibroblasts. This is the first report in which CT findings are described in a case of infantile myofibromatosis with a solitary lesion occurring in the skull.

Ebselen suppressed ET-1-induced contraction and synergetic interaction between oxyhemoglobin and ET-1, where free radical formation was involved. These effects may result from modification of the intracellular regulatory system including protein kinase C, as well as from protection against free radicals.

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