Carbonic anhydrase inhibition and calcium transients in soleus fibers

Abstract

We simultaneously measured cytoplasmic Ca²⁺ transients using Fura-2 and isometric force in rat soleus fiber bundles. In the presence of the carbonic anhydrase inhibitor, chlorzolamide, we observed a decreased amplitude and retarded decay of the Ca²⁺ signal. This corresponded with a decreased isometric force and a retarded muscle relaxation. We conclude that muscle carbonic anhydrase participates in excitation-contraction coupling, possibly by rapidly providing protons that are exchanged for Ca²⁺ across the sarcoplasmic reticulum membrane.