CONGLOMERATE PROLIFERATION OF SMOOTH ENDOPLASMIC RETICULUM IN PROXIMAL TUBULES OF THE KIDNEY

Abstract

In order to study the nature and the significance of the appearance of membraneous conglomeration (Mc) of smooth-surfaced endoplasmic reticulum (SEr) in the proximal tubular cells (PTC) of the kidney, SD strain SPF male rats were given 150mg/kg/day of phenobarbital (PB group) and 40mg/kg/day of 3-methylcholanthrene (MC group) for 4 days, respectively. For controls, non-treated animals and animals only given normal saline or corn oil were used. Biochemical analyses and electron microscopic examinations revealed significantly increased microsomal P-450 not only in the liver but also in renal cortical tissue of MC- and PB group animals together with proliferation of SEr in the liver and of Mc in PTC of the kidney. Proliferation of Mc in PTC was found in all segments of S1, S2, and S3 but was more prominent in the MC group rather than in the PB group. In immunohistochemistry, reactions with MC-induced monoclonal antibodies APL1 and APH8 which are respectively specific for P-450c and P-450d, c were strongly positive in both liver cells and PTC of MC group animals. In PB group animals, however, reaction with PB induced monoclonal antibody APF3 which is specific for P-450b, c was strongly positive in the liver but almost negative in PTC of the kidney. These results indicate that proliferation of Mc in PTC of the kidney is a cellular reaction essentially corresponding to the similar change of hepatic parenchymal cells with induction of P-450 enzymes for metabolizing drugs or noxious chemical substances such as MC and PB.