A CALCIUM-CHANNEL REVERSIBLY BLOCKED BY OMEGA-CONOTOXIN GVIA LACKING THE CLASS-D ALPHA(1) SUBUNIT

IN acutely dissociated rat medium-spiny neostriatal neurons, a substan tial fraction (similar to 40%) of the calcium current block by omega-c onotoxin-GVIA (CgTx) reverses rapidly with washing. The reversibly blo cked current differed in voltage dependence from the current irreversi bly blocked by CgTx. To test the hypothesis that the reversibly blocke d current was attributable to calcium channels with a class D alpha(1) subunit, acutely isolated neurons were subjected to combined patch cl amp/reverse transcription-polymerase chain reaction analysis. These st udies revealed no correlation between the reversibility of the CgTx bl ock and the expression of class D alpha(1) subunit mRNA.