400NL AA facing river shove from huge donk

[Mike MacIntosh]

Was checking out the lobby today and saw a very nice 400nl game (was looking to play 200nl). So I decided to sit down, and after a couple of orbits realized this game was REALLY good. The SB and MP are really loose/terrible players. The MP was running 45/29 over 40 hands. He L/c raises PF VERY often.

What do you do on the river?

Poker Stars, $2/$4 NL Hold'em Cash Game, 6 Players
LeggoPoker.com - Hand History Converter

BB: $159.30
UTG: $435
MP: $342.60
Hero (CO): $416.50
BTN: $714
SB: $386.90

Pre-Flop: A[img]/images/graemlins/spade.gif[/img] A[img]/images/graemlins/heart.gif[/img] dealt to Hero (CO)
UTG folds, MP calls $4, <font color="red">Hero raises to $20</font>, 3 folds, MP calls $16

Flop: ($46) 8[img]/images/graemlins/spade.gif[/img] 7[img]/images/graemlins/club.gif[/img] 5[img]/images/graemlins/heart.gif[/img] (2 Players)
MP checks, <font color="red">Hero bets $32</font>, MP calls $32

Turn: ($110) 3[img]/images/graemlins/spade.gif[/img] (2 Players)
MP checks, <font color="red">Hero bets $75</font>, MP calls $75

River: ($260) T[img]/images/graemlins/spade.gif[/img] (2 Players)
<font color="red">MP bets $215.60 and is All-In</font>, Hero ???