The effect of lanthanum on mitochondria isolated from hybrid rice Fengyou 559 (Oryza sativa L.) was investigated. Through in vivo culture, low-dose La (3+) promoted, but higher dose La (3+), restrained mitochondrial heat production. However, through in vitro incubation, La3+ manifested only inhibitory action on mitochondrial energy turnover, the concentration required for 50% and 100% inhibition being 50.9 and 230.2 p,M (57.6nmo1/mg protein), respectively. In addition, La3+, like Ca (2+) induced rice mitochondrial swelling and decreased membrane potential (Delta psi), which was inhibited by the specific permeability transition inhibitor cyclosporine A (CsA). The induction approached a constant limitation while mitochondrial metabolism was completely prevented by La3+, and microscopy observation showed a high disruption of inner mitochondrial membrane in this state. These results demonstrated that lanthanum influenced rice mitochondria its vivo and in vitro via different action pathways, and the latter involved the opening of rice mitochondrial permeability. (c) 2008 Elsevier B.V. All rights reserved.