As it was reported earlier that isradipine, a Ca superset 2+ antagonist of 
dihydropyridine derivative class, caused regression of nifedipine-induced 
hyperplasia of human gingiva, experiments were performed to examine whether or 
not isradipine would solely inhibit the proliferation of cultured gingival 
fibroblasts. Normal human gingival fibroblast Gin-1 cells were used to test the 
impact of this medication. Fibroblast proliferation in the presence of 
isradipine (10 microM) was examined by using the reagent water-soluble 
tetrazolium-1 (WST-1). The level of basic fibroblast growth factor (bFGF) in the 
cell-free supernatant of each well was determined by using an enzyme-linked 
immunosorvent assay (ELISA) kit. The production of type I collagen was assayed 
by ELISA. Isradipine significantly enhanced the cell proliferation from the 
second day of the culture period. Also, isradipine raised the level of bFGF in 
the culture medium. The same concentration, also significantly enhanced the 
production of type I collagen. In conclusion, we were able to prove that 
isradipine causes the proliferation of cultured gingival fibroblasts as well as 
other dihydropyridine-derivative Ca superset 2+ antagonists do. In order to 
prevent the gingival overgrowth, it is advisable to be very careful in the use 
of isradipine as a therapy for hypertension and other indications.