William B. Gittings

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Contraction-induced activation of a skeletal muscle specific Ca2+ and calmodulin dependent myosin light chain kinase (skMLCK) catalyzes phosphorylation of the myosin regulatory light chain (RLC), a reaction that potentiates twitch force. The purpose of this study was to test the effect of skMLCK gene ablation on the fatigability of mouse extensor digitorum(More)
Pyruvate dehydrogenase (PDH) plays an important role in regulating carbohydrate oxidation in skeletal muscle. PDH is deactivated by a set of PDH kinases (PDK1, PDK2, PDK3, PDK4), with PDK2 and PDK4 being the most predominant isoforms in skeletal muscle. Although PDK2 is the most abundant isoform, few studies have examined its physiological role. The role of(More)
The increase in isometric twitch force observed in fast-twitch rodent muscles during or after activity, known universally as potentiation, is normally associated with myosin regulatory light chain (RLC) phosphorylation. Interestingly, fast muscles from mice devoid of detectable skeletal myosin light chain kinase (skMLCK) retain a reduced ability to(More)
INTRODUCTION Posttetanic potentiation (PTP) and the catchlike property (CLP) enhance contractile function in skeletal muscle. We investigated the CLP during dynamic performance in mouse hindlimb muscles with (wild-type) and without (skMLCK(-/-) ) the primary mechanism for PTP (myosin phosphorylation) (in vitro, 25°C). METHODS Extensor digitorum longus(More)
Skeletal myosin light chain kinase (skMLCK) catalyzed phosphorylation of the myosin regulatory light chain (RLC) increases (i.e. potentiates) mechanical work output of fast skeletal muscle. The influence of this event on contractile economy (i.e. energy cost/work performed) remains controversial, however. Our purpose was to quantify contractile economy of(More)
The isometric potentiation associated with myosin phosphorylation is force dependent. The purpose of this study was to assess the influence of a pre-existing period of isometric force on the concentric force potentiation displayed by mouse muscles with and without the ability to phosphorylate myosin. We tested isometric (ISO) and concentric (CON)(More)
Microcomputed tomography (μCT) is an imaging technology to assess bone microarchitecture, a determinant of bone strength. When measured in vivo, μCT exposes the skeletal site of interest to a dose of radiation, in addition to nearby skeletal muscles as well. Therefore, the aim of this study was to determine the effects of repeated radiation exposure from in(More)
The purpose of this study was to test the hypothesis that the potentiation of concentric twitch force during work cycles is dependent upon both the speed and direction of length change. Concentric and eccentric forces were elicited by stimulating muscles during the shortening and lengthening phases, respectively, of work cycles. Work cycle frequency was(More)
The contractile performance of mammalian fast twitch skeletal muscle is history dependent. The effect of previous or ongoing contractile activity to potentiate force, i.e. increase isometric twitch force, is a fundamental property of fast skeletal muscle. The precise manifestation of force potentiation is dependent upon a variety of factors with two general(More)
The activity dependent potentiation of peak isometric force associated with phosphorylation of the myosin regulatory light chain (RLC) is generally restricted to low activation frequencies. The purpose of this study was to determine if muscle shortening speed influenced the stimulus frequency domain over which concentric force potentiation was observed. To(More)