Antiquity of the chordate pattern of exercise metabolism

Abstract

Vertebrates and cephalochordates generate significant quantities of lactic acid during intense exercise. This is associated with heavy reliance on anaerobic metabolism for intramuscular ATP formation. We report here exercise-related generation of lactate in the appendicularian Oiko-pleura longicauda (Tunicata: Appendicularia) and in the brittle star Ophioderma panamensis (Echinodermata: Ophiuroidea). The chordate-wide distribution of this pattern of activity metabolism suggests its presence in Early Paleozoic prochordates. The presence of the chordate pattern of activity physiology in Ophioderma suggests that very early (Ediacarian?) deuterostomes may also have generated lactate during intense exercise. Further investigation of activity physiology in other echinoderms is warranted.