TABLE 1.

Effect of OPN on the number of osteoclasts exhibiting oscillations in [Ca²⁺]_i

Rat osteoclasts were plated on coverslips coated with BSA or OPN and loaded with fura-2 as described under “Experimental Procedures.” Individual osteoclasts were monitored for periods of at least 25 min. Data show the number of osteoclasts exhibiting oscillations in [Ca²⁺]_i, which were defined as a series of at least 2 transient elevations in the 345/380 ratio of amplitude at least 2 times that of the maximum level of baseline fluctuations. A greater proportion of osteoclasts exhibited oscillations when plated on OPN compared to BSA (significantly different based on chi-square test, p < 0.05). Data are based on responses from a total of 25–26 osteoclasts for each condition from 6 independent preparations of cells.

Substrate	Oscillations	No oscillations	Proportion of osteoclasts exhibiting oscillations
BSA	7	18	28%
OPN	16	10	62%