IADR Abstract Archives
Acetaminophen inhibits TRPV4 channel activation
Objectives: N-acetyl-p-aminophenol (APAP/acetaminophen) is a widely used analgesic/antipyretic with weak inhibitory effects on cyclooxygenase compared to non-steroidal anti-inflammatory drugs. The effect of APAP is mediated by its metabolite, N-arachidonoyl-phenolamine (AM404), that activates transient receptor potential channels, including transient receptor potential vanilloid 1 (TRPV1) and TRP ankyrin 1 (TRPA1) or the cannabinoid receptor type 1. However, the exact molecular mechanism underlying the cellular actions of APAP remains unclear. As we have recently found that APAP promotes cell migration through TRPV4, the effect of APAP on Ca2+-channel activity of TRPV4 was examined in this study.
Methods: A rat pheochromocytoma cell line, PC12, was maintained in Dulbecco’s modified Eagle’s medium containing 10% horse serum and 5% fetal bovine serum. The changing of intracellular Ca2+ concentration of PC12 cells were analyzed by loading acetoxymethylester form of fura-2 to the cells, followed by treatment with each compound in hanks-balanced salt solution. The fura-2 fluorescence image from single cell excited at two alternative wave lengths, 340 and 380 nm was collected. Total RNA of PC12 cells were prepared and subjected to reverse transcription and PCR analyses for examining mRNA expressions.
Results: In PC12 cells, mRNA expressions of TRPV1, TRPV2 and TRPV4, but not TRPA1, were detected. Treatment of PC12 cells with APAP or its metabolite AM404 alone did not affected intracellular Ca2+ concentration. However, both APAP and AM404 completely inhibited the increase of intracellular Ca2+ induced by TRPV4 specific agonist GSK1016790A.
Conclusions: The results suggest that TRPV4 is another target molecule for both APAP and AM404, while the effect of the compounds on TRPV4 was opposite to that on TRPV1 and TRPA1, i.e., AM404 activates TRPV1 and TRPA1, but TRPV4 was inhibited, not activated, by both APAP and AM404. These findings provide new insight for better understanding of the molecular mechanism of action of APAP.
Methods: A rat pheochromocytoma cell line, PC12, was maintained in Dulbecco’s modified Eagle’s medium containing 10% horse serum and 5% fetal bovine serum. The changing of intracellular Ca2+ concentration of PC12 cells were analyzed by loading acetoxymethylester form of fura-2 to the cells, followed by treatment with each compound in hanks-balanced salt solution. The fura-2 fluorescence image from single cell excited at two alternative wave lengths, 340 and 380 nm was collected. Total RNA of PC12 cells were prepared and subjected to reverse transcription and PCR analyses for examining mRNA expressions.
Results: In PC12 cells, mRNA expressions of TRPV1, TRPV2 and TRPV4, but not TRPA1, were detected. Treatment of PC12 cells with APAP or its metabolite AM404 alone did not affected intracellular Ca2+ concentration. However, both APAP and AM404 completely inhibited the increase of intracellular Ca2+ induced by TRPV4 specific agonist GSK1016790A.
Conclusions: The results suggest that TRPV4 is another target molecule for both APAP and AM404, while the effect of the compounds on TRPV4 was opposite to that on TRPV1 and TRPA1, i.e., AM404 activates TRPV1 and TRPA1, but TRPV4 was inhibited, not activated, by both APAP and AM404. These findings provide new insight for better understanding of the molecular mechanism of action of APAP.