This study investigated the effect of the mouse estrous cycle on myocyte contractile function. Female mice displayed irregular estrous cycles unless induced to cycle though exposure to bedding collected from cages housing male mice. Fractional shortening and Ca2+ transient amplitudes were significantly larger in myocytes isolated from mice in estrus. The effect of the estrous cycle was preserved even when cells were paced at a more physiological frequency and in the presence of ?-adrenergic stimulation. Myofilament Ca2+ sensitivity was also modified by the estrous cycle, as myofilaments isolated from the hearts of mice in estrus were least sensitive to Ca2+. However, acute application of either 17?-estradiol or the G protein-coupled estrogen receptor (GPER) agonist, G-1, had no effect on contractions or Ca2+ transients, regardless of the estrous stage. Thus, physiological fluctuations in sex hormone levels modify myocyte contractions, Ca2+ release, and myofilament Ca2+ sensitivity.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:NSHD.ca#10222/15262 |
| Date | 09 July 2012 |
| Creators | MacDonald, Jennifer |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
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