I solve whit this code:
var rowData = {indx1:'data1',index2:'data2'} //assuming indx1 and indx2 editable:false
var rowIndx = grid.addRow({
newRow:{}, //add void row
rowIndx: 0, //at first row
checkEditable:true
});
var pdata = grid.pdata[0]; //get the grid data at position 0
for(i in rowData){
pdata = rowData; //set values of my rowData
}
grid.refreshRow({rowIndx:0}) //refresh the row