SEMINAR: Ca2+-handling at the junctional membranes of skeletal muscle in health, with exercise and aging

The Seminar: Muscle contraction is tightly regulated by the release of Ca2+ form the sarcoplasmic reticulum (SR) following the excitation of the tubular (t-) system, an internalization of the plasma membrane. The t-system and SR are close enough for their respective imbedded proteins to make physical contact and signalling at these junctional membranes is conducted in this manner. How Ca2+ is handled in muscle during rest; and during and after exercise is a major issue that is not understood: There are implications for disease, recovery from exercise and in aging. This seminar will show how the t-system changes its structure for days post damaging, eccentric contractions to allow the t-system to become a Ca2+-buffer in human muscle in association with the period known as delayed onset muscle soreness (DOMS). This response to damaging exercise allows the muscle to maintain fibre viability while the muscle recovers from DOMS. In aging muscle, the handling of Ca2+ by the junctional membranes also changes. The main contributor to this is the ryanodine receptor/Ca2+ release channel that increases its activity in the resting muscle with age. Using novel approaches we describe the activity of the ryanodine receptor in the resting muscle with age and how the associated Ca2+-handling proteins in the SR and t-system adapt to the changing function of the ryanodine receptor, using a colony of aging mice. Exercise was also found to affect the Ca2+ handling by the junctional membranes in these mice as well

The Speaker: Bradley Launikonis is the Head of The Muscle Research Lab at The University of Queensland. He is currently an ARC Future Fellow. He completed his PhD at La Trobe University in 2000 and a postdoc at Rush Medical Centre, Chicago (2002-2006). The Muscle Research Lab focuses on muscle cell physiology in health, disease and exercise, using confocal microscopy to image membrane structure and Ca2+ dynamics within isolated muscle fibres. More recently this structural and functional work has been translated into fibres isolated from human muscle biopsies from work in rodent muscle.