Gordon and Dan are among Glasgow's replacements for Sunday's game.
Hugh Campbell, Glasgow's head coach, explained that Scott and Calvin have been retained after "playing outstandingly well" in November's four Celtic League matches.
Hugh, talking to The Scotsman, admitted that fatigue was a factor in the decision to leave such key figures out of the starting line-up. He said: "All our Scotland players had four weeks of pressure and they did come back pretty tired. Gordon was fine about the decision and Scott is fresh and up to speed - it does also offer us a strong bench."
Glasgow include four returning Scotland players for Sunday's match – Andy Henderson, Sean Lamont, Donnie Macfadyen, and Jon Petrie. But another cap, Graeme Morrison, could not be considered because of a back injury.
Euan Murray returns to the Glasgow team despite his 12-week suspension following his dismissal in the league match against Llanelli two weeks ago. The SRU's appeal panel ruled earlier this week that the prop could be considered for selection for Sunday's cup match because an appeal hearing could not be held until next week.
"Euan's delighted that he's playing," said Hugh. "It's a massive boost for him."
There are six changes in personnel from the team who gained a bonus point in defeat by Leinster by 16-22 at Donnybrook last Friday. In the pack Euan is at tight head for Andrew Kelly, Donnie comes in at open side for Andrew Wilson, and JP at No.8 for John Beattie. JP also resumes the captaincy.
Among the backs, Sam Pinder returns in place of Graeme Beveridge at scrum half, Sean Lamont is in for Kenny Logan on the left wing, and Andy Henderson resumes at inside centre, with Gareth Maclure switching to the right wing and Rory Kerr to full back instead of Colin Shaw.
Glasgow
15 Rory Kerr
14 Gareth Maclure
13 Andy Craig
12 Andy Henderson
11 Sean Lamont
10 Calvin Howarth
9 Sam Pinder
1 Kevin Tkachuk
2 Scott Lawson
3 Euan Murray
4 Andy Hall
5 Dan Turner
6 Cammy Mather
8 Jon Petrie (captain)
7 Donnie Macfadyen
Replacements
16 Gordon Bulloch
17 Andrew Kelly
18 John Beattie
19 Andrew Wilson
20 Graeme Beveridge
21 Dan Parks
22 Kenny Logan