[Effect of caffeine on the processes of intracellular Ca2+ concentration regulation in isolated snail neurons].

The Ca2+ indicator Fura-2 was used to measure changes of cytoplasmic free Ca2+ concentration ([Ca2+]in) in isolated neurons of the snail Helix pomatia occurring through prolonged plasma membrane depolarization. An amplitude of Ca2+ response did not practically depend on value of depolarization in the presence of 5 mmol/l of caffeine unlike normal solution, which permitted suggesting that caffeine activated calcium-dependent Ca2+ release from the intracellular stores, which was a main factor of [Ca2+]in increase during depolarization. The processes of [Ca2+]in relaxation to the rest levels were approximated monoexponentially and occurred 2 times more rapidly in caffeine than in normal solution. An increase of the [Ca2+]in relaxation rate was provided probably, by a rise in the efficiency of the intracellular Ca2+ pumps able to decrease the rest level of [Ca2+]in even lower than that one under normal extracellular solution conditions.