Contractile activation characteristics of single permeabilized fibres from levator palpebrae superioris, orbicularis oculi and vastus lateralis muscles from humans

Abstract

1. We investigated the contractile activation characteristics of single membrane-permeabilized fibres from the following muscles from humans: the levator palpebrae superioris (LPS), an extraocular muscle; the orbicularis oculi (OO), a facial muscle; and the vastus lateralis (VL), a major muscle of the thigh. 2. Single permeabilized muscle fibres were isolated from each of the different muscles, attached to a sensitive force transducer and activated by rapid immersion in buffered solutions of varying [Ca2+] and [Sr2+]. Fibres were allocated into discrete populations based on their contractile characteristics, including their differential force responses during Ca2+ and Sr2+ activation. 3. Wit..