Passing Value From Stored Proc To Another

Guys
I have a simple 'black box' proc deriving start and end dates below (the actual values will be derived from more complex code but here for simplicity are hard coded)

create proc upGetDates
as
declare @start datetime ,
@end datetime

select@start = '2001-01-01' ,
@end = '2007-12-31'
go

I want to reuse this proc many times for different reports and using the date values in the calling sp

an example in pseudo code would be

create proc usedates
as
declare@rstart datetime ,
@rend datetime

exec upGetDates @rstart = @start , @rend = @end -- obtaining dates from ---called 'black box' proc
select * from tablename where datecreated >= @rstart and datecreated < @rend
go

Not sure how to 'trap' the dates from the called proc

Can it be done ?

Thanks in anticipation