Increased intracellular Ca²⁺: A critical link in the pathophysiology of sepsis?

Severe bloodstream-borne infection - i.e., sepsis - and the resulting multiorgan failure are now the most common cause of death in many intensive care units. One of the most fundamentally important and controversial issues concerning the pathophysiology of sepsis is the role of intracellular free calcium concentration ([Ca²⁺]_i) in this disorder. Because of the critical role of calcium as an intracellular second messenger and as a potential cellular toxin, resolution of this issue is crucial. Using ¹⁹F NMR spectroscopy and the calcium indicator 5,5′-difluorobis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetate we demonstrate in the intact perfused organ, the rat thoracic aorta, that [Ca²⁺]_i in aortic smooth muscle is increased >2-fold during sepsis. Furthermore, we determined that sodium dantrolene, a drug that decreases release of calcium from the sarcoplasmic reticulum and that is lifesaving in malignant hyperthermia (a disorder due to increased [Ca²⁺]_i), is able to reduce the elevated [Ca²⁺]_i in sepsis to control values when added in vitro or when given in vivo to the animal. These results suggest that an increase in [Ca²⁺]_i is an early event in sepsis and that increased [Ca²⁺]_i may be responsible for, or contribute to, cellular injury. Dantrolene may offer a therapeutic strategy in the treatment of sepsis.