Effects of vinblastine on calcium distribution pattern and Ca2+,Mg(2+)-adenosine triphosphatase in rat incisor maturation ameloblasts.

Vinblastine is known to affect secretory and transport functions of ameloblasts. The effects of vinblastine on distribution patterns of membrane-associated calcium and Ca2+,Mg(2+)-ATPase in maturation ameloblasts were investigated cytochemically. The potassium pyroantimonate (PPA) method was used for localizing calcium and a modified Wachstein-Meisel medium was used to localize Ca2+,Mg(2+)-ATPase. Ultrastructural changes induced by vinblastine included dislocated organelles and reduction or elimination of the ruffled border of the ameloblasts. Membrane-associated calcium pyroantimonate deposits were markedly reduced. The intensity of Ca2+,Mg(2+)-ATPase reaction product was also markedly reduced by vinblastine. Concomitant reduction of membrane-associated calcium and Ca2+,Mg(2+)-ATPase lends support to a role for maturation ameloblasts in control of a cyclic pattern of influx of calcium to mineralizing enamel.