Fig. 1.

Mechanisms involved in helium-induced cardioprotection. This figure summarizes the known mechanisms in helium-induced cardioprotection, mainly via the RISK pathway, which is closely related to alterations in caveolin-related processes. Helium is depicted as a purple circle (He). Red arrows indicate an activating or upregulatory effect; squares indicate a suppressive or downregulatory effect. Intracellular the mechanisms converge on the mitochondria and preventing the mPTP from opening indicates cardioprotection. Also, the potential pathway of “remote condition” by helium has been depicted on the left side of the picture. Unknown and identified factors (caveolin, probably carried by exosomes) mediate a distant organ protection and can improve the mitochondrial respiration in distant cells. MEK-1, mitogen-activated protein kinase-extracellular signal-regulated kinase-1; ERK1/2, extracellular signal-regulated kinase 1/2; IP3, inositol triphosphate-3; DAG, diacylglycerol; PKC-ε, protein kinase C epsilon; GSK3β, glycogen synthase kinase 3β; PI3K, phosphatidylinositol-3-kinase, PDK-1, phosphoinositide-dependent protein kinase-1; PKB, protein kinase B; mTOR, mammalian target of rapamycin; P53, tumour protein P53; mPTP mitochondrial permeability transition pore; eNOS, endothelial nitric oxide synthase; NO, nitric oxide; L-NAME, L-NG-nitroarginine methyl esther; PKA, protein kinase A; mKCa, mitochondrial calcium-sensitive potassium channel; ROS, reactive oxygen species; Pi, inorganic phosphate; ATP, adenosine triphosphate; ADP, adenosine diphosphate