Calcium uptake and membrane potential in rat brain mitochondria during hypertension

Abstract

Mitochondria contribute directly to the intracellular Ca2+ homeostasis. Ca2+ uptake is an energy-requiring process driven by the electric potential established across the mitochondrial inner membrane. Several abnormalities in regard to Ca2+ metabolism has been observed in spontaneously hypertensive rats (SHR). It is important to investigate if calcium handling and functionality in mitochondria might be altered in brain of hypertensive rats. Therefore, we investigated if membrane potential and Ca2+ uptake change during hypertension and aging in SHR rats of 1 and 7 months-age. We used the safranine technique to determine transmembrane potential and the rate of Ca2+ transport was measured with the Ca2+ indicator Arsenazo III. Transmembrane potential diminished more in SHR rats of 1 month-age than 7 months old rats. Whereas, mitochondrial Ca2+ uptake decreased in hypertensive brain rats of 1 month-age compared brain mitochondria of SHR rats of 7 month old age. These data suggest that mitochondrial functionality is reduced with age and the establishment of hypertension. Acknowledgements The authors appreciate the partial economic support of grants from CONACYT (43705) and CIC-UMSNH (2.16-2005).