Sorry this Video is in German language, but I reckon it's fun to watch anyways. Gottfried Biegelmeier of Felten&Gillaume Austria (Later Moeller, now Eaton), often credited as an inventor of the general use GFCI in 1957, endures a few hundred different AC shocks while connected to an ECG and with a defibrillator on standby, to test his products. You can see that the ECG is altered for a few beats after the shock, and the muscular contractions of the whole body.
Body resistances down to 1kohm, peak body currents around 0.4 Amps.
Back then, they took this as prove that a GFCI protects from heart fibrillation, even thou the mechanics take a moment to operate. I don't know how thoughts on this are today.
Stole the link from another German forum, TexasRanger knows which one https://www.youtube.com/watch?v=08r27LnLHCM