Reactive oxygen species are important mediators of taurine release from skeletal muscle cells

Abstract

The present study illustrates elements of the signal cascades involved in the activation of taurine efflux pathways in myotubes derived from skeletal muscle cells. Exposing primary skeletal muscle cells, loaded with 14C-taurine, to 1) hypotonic media, 2) the phospholipase A2 (PLA2) activator melittin, 3) anoxia, or 4) lysophosphatidyl choline (LPC) causes an increase in 14C-taurine release and a concomitant production of reactive oxygen species (ROS). The antioxidants butulated hydroxy toluene and vitamin E inhibit the taurine efflux after cell swelling, anoxia, and addition of LPC. The muscle cells possess two separate taurine efflux pathways, i.e., a swelling- and melittin-induced pathway that requires 5-lipoxygenase activity for activation and a LPC-induced pathway. The two pathways are distinguished by their opposing sensitivity toward the anion channel blocker DIDS and cholesterol. These data provide evidence for PLA2 products and ROS as key mediators of the signal cascade leading to taurine efflux in muscle.