The present invention relates to compositions comprising docosapentaenoic acid and methods of reducing lipid parameters, such as triglycerides, total cholesterol, low density lipoprotein cholesterol, non-HDL cholesterol, free fatty acids, and other lipids, comprising administration of omega-3 docosapentaenoic acid. The invention also provides antisense nucleic acid molecules, recombinant expression vectors containing TWIK nucleic acid molecules, host cells into which the expression vectors have been introduced, and nonhuman transgenic animals in which a TWIK gene has been introduced or disrupted. An actuator mechanically rotates the nozzle.