Fig. 1. The chamber assembly. The oxygen electrode (oe) was screwed into the chamber body by means of a membrane sleeve (es). Ringer’s solution flowed through the chamber via inlet (ch_in) and outlet (ch_out) studs made of Kel-F. A water jacket (wj) surrounded the chamber (ch) and oxygen electrode. Water entered the jacket through a side port (wj_in) and exited at the rear of the jacket (wj_out). The chloride-coated stimulating electrodes (se) were connected via wires (st) to a Grass S48 stimulator. A temperature probe (tp) was located in the chamber cup and connected to a K-type thermometer (th). The muscle was attached at one end to a servo arm (sa) and at the other end to a force transducer (ft) mounted in a Kel-F stud. A glass-encapsulated stir bar (sb) lay in the cup of the chamber and was used to mix the Ringer’s solution. The glass lid (cl) was sealed using silicon high vacuum grease.