Figure 1.

SR Ca²⁺ storage and altered Ca²⁺-related protein expression. (a) Ca²⁺ changes, assessed in wild-type (+/+) and αMHC^403/+ (403/+) myocytes, in response to a bolus administration of 10 mM caffeine (vertical arrows indicate time of administration). (b) Western blot analysis of calsequestrin (CSQ) and components of the quaternary complex in myofibrillar protein extracts from wild-type and αMHC^403/+ mice aged 30–50 weeks. Coomassie staining indicates loading of samples in each lane. Treatment of αMHC^403/+ mice with diltiazem led to normalization of all four components of the RyR2 complex — calsequestrin (8 days treatment), triadin, junctin, and RyR2 (30 weeks treatment). (c) Time course study of changes in calsequestrin protein expression in equal amounts of myofibrillar extracts from mice aged 2, 4, 6, 8, 12, and 30 weeks.