New calcite Sr/Sr data for 47 limestones from the metamorphosed and deformed Neoproterozoic–Cambrian Dalradian Supergroup of Scotland and Ireland are used to identify secular trends in seawater Sr/Sr through the Dalradian succession and to constrain its depositional age. Dalradian limestones commonly have Sr .1000 ppm, indicating primary aragonite and marine diagenesis. Low Mn, Mn/Sr ,0.6, O an...

Smaller Ca2+ transients and systolic dysfunction in heart failure (HF) can be largely explained by reduced total sarcoplasmic reticulum (SR) Ca2+ content ([Ca]SRT). However, it is unknown whether low [Ca]SRT is manifest as reduced: (1) intra-SR free [Ca2+] ([Ca2+]SR), (2) intra-SR Ca2+ buffering, or (3) SR volume (as percentage of cell volume). Here we assess these possibilities in a well-chara...