Abstract: Aim Intracellular calcium ([Ca²⁺]i) is mainly regulated by mitochondria and endoplasmic reticula. This study was carried out to ascertain whether the elementary mechanism of the effects of etimicin (EM) and gentamicin (GM) on [Ca²⁺]i is related to their effects on mitochondrion Ca²⁺-uptake and endoplasmic reticulum Ca²⁺-uptake. Methods The effects of GM and EM on [Ca²⁺]i in LLC-PK1 were determined with a fluorescent probe of Fura-2/AM. The effects of EM and GM on mitochondrion Ca²⁺-uptake and endoplasmic reticulum Ca²⁺-uptake were determined by isotope indicator (45Ca²⁺). Results EM and GM at the concentration of 1 mmol·L^-1 had no significant effect on [Ca²⁺]i i (P > 0.05) and at 10 mmol·L^-1 significantly caused [Ca²⁺]i to increase (P <0.01). EM and GM at 1 mmol·L^-1 caused mitochondrion Ca²⁺-uptake to ascend dramatically (P< 0.05) and at 10 mmol·L^-1 caused mitochondrion Ca²⁺-uptake to descend significantly. EM and GM at more than 0.34 mmol·L-1 significantly inhibited endoplasmic reticulum Ca²⁺-uptake (P <0.05 or 0.01). Conclusion No variation of [Ca²⁺]i caused by EM and GM at lower concentrations might relate to the equilibrium of their promotion of mitochondrion Ca²⁺-uptake with their inhibition of endoplasmic reticulum Ca²⁺-uptake. The elevation of [Ca²⁺]i caused by EM and GM at higher concentrations might correlate with their inhibition of mitochondrion Ca²⁺-uptake and endoplasmic reticulum Ca²⁺-uptake.

Key words: etimicin, etimicin, gentamicin, gentamicin, Ca2+ homeostasis, Ca2+ homeostasis, mitochondria, mitochondria, endoplasmic reticula, endoplasmic reticula