Effect of vinblastine on the brush border of proximal tubule cells of rat kidney.

A vinblastine-induced lesion of the brush border of proximal tubule cells of rat kidney was studied by scanning and transmission electron microscopy. Adult rats were given two tail-vein injections of vinblastine sulfate and then sacrificed either three or sixteen hours after administration of the first injection. The proximal tubules of animals treated with the drug for three hours differed from those of saline-treated controls in possessing (1) well defined areas of apical cell surface devoid of microvilli and (2) fewer microcraters in the brush border. In tubules of animals treated with vinblastine for sixteen hours, the areas devoid of microvilli were much more extensive, and microcraters were less frequently seen. Cilia did not appear to be affected by exposure to the drug and were observed both in regions devoid of microvilli and in areas with a well developed brush border. The mechanism of action of vinblastine in eliciting focal loss of microvilli of proximal tubule cells is not known. Several hypotheses to account for this lesion of the brush border are discussed.