How to apply imfilter function in 3d

oh = [-1 9 -45 0 45 -9 1] / 60;
V_x   = imfilter( V, oh, 'corr', 'replicate', 'same' );
V_y   = imfilter( V, oh', 'corr', 'replicate', 'same' );

Now, for applying imfilter with respect to z direction, I made this:

 function V_z = central_diff_wrt_z( V )
 [nRow, nCol, nDep] = size(V);
 idx                 = 2:nDep-1;
 V_z                = zeros( size(V) );
 V_z(:,:,2:end-1)   = ( V(:,:,idx+1) - V(:,:,idx-1) ) / 2;
 V_z(:,:,1)         = ( V(:,:,2) - V(:,:,1) ) / 2;
 V_z(:,:,end)       = ( V(:,:,end) - V(:,:,end-1) ) / 2;
 end

However, I want to use imfilter in z-direction. How to use it?