Passing Parms With No Values To A Stored Procedure

I'm want to pass empty parm value to a stored procedure. I'm new at this stuff and not sure how to do this. To make it work I can put values in parms and it works great. I don't want to populate some of the fields in the table with values. The fields are cnty,dist,beat,convertedkey. Anyone know how I can get it done? Code below. Thanks for your help!

int shift = Convert.ToInt16(dr.Cells[1].Value.ToString());

int prior = Convert.ToInt16(dr.Cells[2].Value.ToString());

string lname = Convert.ToString(dr.Cells[3].Value.ToString());

string fname = Convert.ToString(dr.Cells[4].Value.ToString());

string unit = Convert.ToString(dr.Cells[5].Value.ToString());

string handle = Convert.ToString(dr.Cells.Value.ToString());

int badge = Convert.ToInt16(dr.Cells[7].Value.ToString());

string cnty = Convert.ToString('1');

string dist = Convert.ToString('1');

int beat = Convert.ToInt16(1);

int convertedkey = Convert.ToInt16(1);

char action = 'I';

char assign = 'Y';

var db = new dpoffassignedDataContext();

var q = db.SP_DpAssignAllOfficers(action, convertedkey, shift, prior, lname, fname, unit, handle, cnty, dist, beat, badge, assign);





Stored procedure below;

ALTER PROCEDURE SP_DpAssignAllOfficers

(

@action nvarchar(1),

@int_id int,

@shift int,

@prior int,

@lname nvarchar(20),

@fname nvarchar(20),

@unit nvarchar(5),

@handle nvarchar(10),

@cnty nvarchar(10),

@dist nvarchar(10),

@beat int,

@badge int,

@assign char



)

AS

INSERT

INTO dpofficers(dpo_prior,dpo_lname,dpo_fname,dpo_unit,dpo_handle,dpo_cnty,dpo_dist,dpo_beat,dpo_badge,dpo_shift)

VALUES (@prior,@lname,@fname,@unit,@handle,@cnty,@dist,@beat,@badge,@shift)