Mitochondrial adenosine triphosphatase in the oxyphil cells of a renal oncocytoma

Oxyphil cells are characterized by cytoplasm packed with large numbers of mitochondria. Study of these unusual cells may provide information about the regulation of mitochondrial biogenesis. Although it has been suggested that this is a compensatory proliferation due to a mitochondrial dysfunction, no such dysfunction has been well documented. In this study we considered the possibility of dysfunction in the mitochondrial enzyme F1/Fo-adenosine triphosphatase(ATPase) as a stimulating factor involved in the mitochondrial proliferation of oxyphil cells. Mitochondria isolated from frozen tissue of a renal oncocytoma showing structural integrity and purity by electron microscopy were studied. Submitochondrial particles formed by sonic disruption showed the presence of the F1 component of mitochondrial ATPase with electron microscopy which was functionally active. The oligomycinsensitive ATPase activity from the renal oncocytoma was 0.133 mumol/min.mg submitochondrial particle protein which was higher than the readings obtained from normal kidney tissue (0.091 mumol/min.mg SMP protein) obtained from hamsters. Normal human renal tissue obtained at autopsy contained only nonfunctional mitochondria and therefore could not be used as control tissue. Mitochondrial ATPase dysfunction does not appear to be the inciting factor in the proliferation of mitochondria seen in oxyphil cell metaplasia and future studies should consider other possibilities. Preliminary functional studies of this nature can be performed with properly prepared frozen surgical tissue.