Effects of Calmodulin Inhibitors on the Cellular Metabolism of sup 45 Ca and sup 210 Pb

摘要

Altered Ca sup ++ homeostasis may result from the direct inhibition of calmodulin-dependent or -independent transport processes. Changes in cell function not directly related to the transport of Ca, e.g., uncoupling of oxidative phosphorylation or altered membrane permeability also disrupt cell calcium metabolism. Thus, the effects of the calmodulin inhibitor W-13 on cell Pb sup ++ metabolism may be due to its direct effects on Pb sup ++ transporting Ca sup ++ pumps, or indirectly as a result of changes in Ca sup ++ homeostasis. Direct comparison of the effects of W-13 on the metabolism of Pb and Ca is impaired by differences in the kinetic distribution and behavior of Pb and Ca. A further complication is that the calmodulin-dependent processes are most active during periods of elevated intracellular Ca sup ++ . The preliminary experiments reported here were conducted in unstimulated cells which have a low resting level of cytosolic Ca sup ++ . Therefore, W-13 induced alterations in cell Ca sup ++ and Pb sup ++ may not reflect the changes which could occur in stimulated cells. 1 ref., 1 fig. (ERA citation 12:037937)