The Effect Of L-type Calcium Channel On Calcium Concentration In Odontoblast Cells

Dentin may be considered as a calcified connective tissue, the processes of the dentin formation includes simultaneously the secretary synthesis of the proteinaceous dentin matrix and deposition of the calcium in this matrix.lt is suggested that calcium is not only a basic substance of the organs, but also an important second messenger in cellular signal transduction that modulates versatile activities of cells.As part of this, the odontoblasts actively transport Ca2+ ions towards the site of mineral formation by the concerted action of transmembraneous transport mechanisms, including Ca-ATPase, Na+/Ca2+ exchangers and calcium channels of the L-type, and possibly intracellular Ca2+-binding proteins.In the literature, It was reported that L-type calcium channel,voltage-gated channel.played an important role of transporting calcium into the plasma. It consists of 5 subunits, a i> a 2> 0 ^ 6 and Y , among them, a j is the major fractional part. Three gene types of a j subunits have been found till now.they are a jC> a jD and a ^.However, whether all the three types are expressed in odontoblast cells is still unknown.In the present study, we used immunohistochemistry method, antisense oligodeoxynucleotides technique and laser scanning confocal microscopy examining the distribution of L-type calcium channel a iD subunit on odontoblast cells in vitro, and the effect of calcium channel on intracellular calcium concentration in the cells, investigating cytologically and molecularly the relationship among the odontoblast cells, L-type calcium channel and intracellular calcium. The result showed:l.The expression of L-type calcium channel a ,D isoform on the membrane of odontoblast cells decreased after the application of the antisense oligodeoxynucleotides, which proved that a jD isoform of L-type calcium channel existed in odontoblast cells, and located on the membrane.2. L-type calcium channel played a very important role in intracellular calcium transportation of odontoblast cells and involved in the process of the dentin mineralization. L-type calcium channel was insensitive to parathyroid horomone and nifedipine when the expression of L-type calcium channel a jD isoform was blocked by antisense oligodeoxynucleotides. This suggested that the a tD isoform be the major functional unit.The results of this study have provided theoretic basis for further investigation on the mechanism of the calcium transportation, dentin mineralization and signal transduction hi odontoblast cells.