PK-THPP is a potent antagonist of tandem pore potassium channel subunit TASK-3 (KCNK9, K2P9.1) with an IC50 value of 35 nM for TASK-3 compared to 303 nM for TASK-1 and with >140 fold selectivity over a wider range of potassium channels. PK-THPP was found to act as a respiratory stimulant, stimulating breathing in isoflurane-anesthetized rats.