Calcium Signals Are Affected by Ciprofloxacin as a Consequence of Reduction of Mitochondrial DNA Content in Jurkat Cells

Abstract

The effects of ciprofloxacin on mitochondrial DNA (mtDNA) content, oxygen consumption, mitochondrial membrane potential, cellular ATP formation, and capacitative Ca ²⁺ entry into Jurkat cells were investigated. In cells incubated for several days with 25 μg/ml ciprofloxacin, a 60% reduction of mtDNA content, inhibition of the respiratory chain, and a significant decrease in mitochondrial membrane potential were observed. These changes led to a decrease in the calcium buffering capacity of mitochondria which, in turn, resulted in a gradual inhibition of the capacitative Ca ²⁺ entry. On days 4, 7, and 11 of incubation with ciprofloxacin, the initial rates of Ca ²⁺ entry were reduced by 33%, 50%, and 50%, respectively. Ciprofloxacin caused a transient decrease in the cellular capability for ATP formation. In cells incubated for 15 min with glucose, pyruvate, and glutamine as exogenous fuel, ciprofloxacin reduced ATP content by 16% and 35% on days 4 and 7, respectively, of incubation with the drug. However, on day 11 of incubation with ciprofloxacin, a recovery of cellular ATP formation was observed. In conclusion, long-term exposure of Jurkat cells to ciprofloxacin at a concentration of 25 μg/ml seriously affects cellular energy metabolism and calcium homeostasis.