Effects of Indomethacin on Intracellular pH and Na^+/H^+ Exchanger in the Human Monocytes

Abstract

The ability to maintain optimal intracellular pH (pH(i)) is an essential requirement for all cells. Na⁺-H⁺ exchanger (NHE), a ubiquitously expressed transmembrane protein, has been found widely as a major acid extruder in many different cell types, including human monocytes. We therefore investigated the mechanism of the active pH(i) recovery from intracellular acidosis (induced by NH₄Cl prepulse) using intracellular 2',7'-bis (2-carboxethyl)-5(6)-carboxyl-fluorescein (BCECF) fluorescence in cultured human monocytes. Indomethacin is a potent, nonselective inhibitor of cyclooxygenases. Due to its toxicity, the clinical use of indomethacin as an analgesic-antipyretic agent is limited. However, it has recently been found that indomethacin can effectively treat many inflammatory/immune disorders. In this study, we further investigated the effect of indomethacin on the pHi and explored the underlying mechanism. In HEPES (nominally HCO₃⁻-free) Tyrode solution, a pH(i) recovery from induced intracellular acidosis could be blocked completely by 30 μM HOE 694, a specific NHE1 inhibitor, or by removing [Na⁺]₀. Therefore, in the present study, we provided functional evidence, physiologically and pharmacologically, that the HCO₃⁻-independent acid extruder was mostly likely the NHE1 which was involved in acid extrusion in the human monocytes. Moreover, indomethacin (1 μM-1 mM) decreased pH(i) levels in a concentration-dependent manner and significantly suppressed the activity of the NHE1, suggesting that indomethacin-induced intracellular acidosis is caused both by the inhibition of NHE1 activity and the non-specified NHE1-independent acidifying mechanism. In conclusion, our present study demonstrates that NHE1 exists functionally in human monocytes, and the indomethacin-induced pHi decreasing is summation effects on NHE1-dependent and -independent mechanism.

Association of Activation of Induced COX-2, iNOS and Cytokines with NF-kappa B Depression by Taiwan Wild Grape Ethanolic Extract in Mice

“…VTT EtOH and Indo had significant effects on the number of abdominal constrictions and The formalin-induced licking response has been reported to be biphasic. Centrally acting drugs can inhibit both phases, whereas peripherally acting drugs, such as NSAIDs, can inhibit only the second phase (28,37). In the early phase of this study, neither VTT EtOH nor Indo exhibited any antinociceptive activity compared to that in the control (Table 1).…”

“…The formalin-induced licking response is a frequently used animal model to study analgesic and anti-inflammatory effects, because the response is highly specific for identifying the central and peripheral components of pain. Therefore, the formalin test can effectively assess the effects of a drug against inflammatory and non-inflammatory pain (28,37). Inflammation is one of the most important defense mechanisms against invading pathogens or damaged cells (9).…”

Value of indomethacin suppository for preoperative analgesia and anti-inflammation in laparoscopic appendectomy: a protocol of prospective, double-blinded, single-centre, randomised controlled trial in China

“…Indomethacin suppository reduces neutrophil chemotaxis, thereby inhibiting neutrophil activation and reducing the inflammatory response. 27 Indomethacin reduces the synthesis and release of prostaglandin E2 by inhibiting COX, which regulates autoimmunity by altering the IL-23 axis and the development of regulatory T cells. 28 This trial hopes to explore the effect of indomethacin suppository and lornoxicam on immune function by comparing their analgesic and anti-inflammatory functions when applied preoperatively in LA, with a view to informing the optimisation of the LA perioperative pain management process and facilitating the development of a daytime LA model.…”