Neuronal changes in Ca2+ and pH regulated by a Ca antagonist under extracellular acidosis

Investigation of intracellular Ca2+ ([Ca2+]i) levels and intracellular pH ( [pH]i) gradient, employing the respective fluorescentdyes, fura-2 and BCECF , showed that [Ca2+]i movement may be an important factor influencing neuro nal functions, such as secondary messengers in signal transduction, and tha t [pH]i fluctuations may regulate neuronal vulne rability. To further chara cterize the relation between neuronal regulation and changes in both [Ca2+] i levels and [pH]i gradient under acidosis (pH 6.6), we have sought to bett er quantify the fluorointensity of Ca2+ and pH in cultured cerebellar granu le cells, by color image integration, utilizing a novel culture dish with a non-fluorescent glass bottom, and a highly sensitive image analyzing syste m. The results compare both high and low potential KCl sensitive neuronal c ell groups, and demonstrate the inhibitory effects of nimodipine (pico mola r range) on K-induced changes in [Ca2+]i and [pH]i under acidosis, indicati ng this calcium antagonist as a potential modulator of neuronal cell functi ons under acidotic conditions. These findings also demonstrate simultaneous quantitative image analysis to be a valuable technique for detecting neuro nal activity and dysfunction associated with changes in [Ca2+]i and [pH]i.