The SAL Superman has some pretty incredible regenerative powers:
At the 3 minute mark, Captain Luthor stabs Clark in the heart with a kryptonite blade while in low orbit.
Clark plummets, but yanks out the blade from his chest and stops himself from crashing inches from the ground and immediately flies back up at full speed.
Dude has been guzzling solar radiation for 40 years now and seems to have built up some immunity to Green K.