We have studied the effects of acute administration of tri-iodothyronine (T3) on cytosolic free calcium levels [Ca2+]i in single rat myocytes microinjected with aequorin. Ventricular myocytes were isolated by perfusing rat hearts with collagenase, and healthy, rod-shaped cells were injected to <1% of their volume with aequorin. The photons emitted from single cells were measured and a conversion to [Ca2+]i made on the basis of an in vitro calibration after the remaining aequorin had been discharged by cell lysis. Only cells that depolarized reversibly (showing elevated [Ca2+]i levels) when superfused with 80mM KC1, and which gave a substantial signal on lysis with distilled water were used. The [Ca2+]i rose from a resting value of 150±56nM (mean ± SD, n=14) by 127±47nM on depolarization with 80mM KC1. Application of T3 (1-100nM) led to an increase (P<0.05) in [Ca2+]i (mean amplitude of 152±35nM) before returning to baseline. The median duration of these events was 10 min (range = 1.4-34.4 min). The time to response was shorter when lOOnM T3 was applied (median and range; 6.8, 0-14 min) than when 1nM T3 was used (16, 7.0-56.1 min) (P<0.05). To conclude, physiological concentrations of thyroid hormones caused rapid but transient stimulation of [Ca2+]i in single rat myocytes.
Journal of Molecular Endocrinology is committed to supporting researchers in demonstrating the impact of their articles published in the journal.
The two types of article metrics we measure are (i) more traditional full-text views and pdf downloads, and (ii) Altmetric data, which shows the wider impact of articles in a range of non-traditional sources, such as social media.
More information is on the Reasons to publish page.
|Sept 2018 onwards||Past Year||Past 30 Days|
|Full Text Views||0||0||0|