A metabolic futile cycle is operating in gas gland cells of the swimbladder.

H+/单羧酸转运体MCT1b和MCT4b在河豚膀胱中高表达。代谢酶的免疫组织化学分析表明，糖异生酶果糖-1,6-二磷酸酶（Fbp1）和糖酵解酶甘油醛-3-磷酸脱氢酶（Gapdh）在气体腺细胞中高度表达。糖酵解和糖异生反应的同时催化表明，在气腺细胞中存在一种无用的循环，以维持低ATP水平并产生有助于降低O2溶解度的热量

H+/monocarboxylate transporters MCT1b and MCT4b were found to be highly expressed in the fugu swimbladder. Immunohistochemical analyses of metabolic enzymes demonstrated that a gluconeogenesis enzyme fructose-1,6-bisphosphatase (Fbp1) and a glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (Gapdh) are highly expressed in gas gland cells. The simultaneous catalyses of glycolysis and gluconeogenesis reactions suggest the presence of a futile cycle in gas gland cells to maintain the levels of ATP low and to generate heat that helps reduce the solubility of O2