Which statement about cardiac muscle is FALSE? Which statement about cardiac muscle is FALSE? Cardiac muscle cells use Ca2+ ions released from the sarcoplasmic reticulum. Calcium-induced calcium release is when extracellular Ca2+ stimulates release of Ca2+ from the sarcoplasmic reticulum. Cardiac muscle cells must obey the all-or-none law of contraction. The energy demand of cardiac muscle cells is high because they have many mitochondria. Intercalated disks contain both desmosomes for firm attachment and gap junctions to allow communication.