The mitochondrial membrane potential and the sources of reactive oxygen species in the hemocytes of the ark clam Anadara kagoshimensis under hypoosmotic stress

To compensate for changes in cell volume caused by changes in salt concentration, mollusks use regulatory mechanisms such as the regulation of volume decrease (RVD). This may increase the rate of aerobic metabolism and lead to an increase in reactive oxygen species (ROS). This study examined the production of ROS in the mitochondria of Anadara kagoshiensis hemocytes, the effect of mitochondrial inhibitors on osmotic stability in hemocytes, and the dynamics of changes in ROS levels and mitochondrial membrane potential when RVD is activated under hypo-osmotic conditions. Hemocytes maintained at a control osmolarity of 460 mOsm l⁻¹ showed significant decreases in ROS production following incubation with complex III inhibitors (S3QEL). Hypoosmotic shock stimulated RVD in all experimental groups. The cell volume increased by about 70 % immediately after osmolarity was reduced, and then decreased by about 40 % over the next 30 min. A reduction in osmolarity from about 460 to 200 mOsm l⁻¹ significantly decreased ROS and mitochondrial potentials in A. kashimensis hemocyctes. Inhibitors of mitochondrial complexes did not affect changes in ROS or mitochondria potentials in A kashimiensis hemocytes under hypoosmotic conditions or in hemocyte volume regulation mechanisms.