[Characteristics of calcium and sodium transport in the synaptosomes and subsynaptosomal structures of the brain of spontaneously hypertensive rats].

Calcium and sodium synaptosomal uptake and mitochondrial and microsomal accumulation were examined in the brain of rats with inherited spontaneous hypertension, using 45Ca and 22Na labels. In the brain synaptosomes of hypertensive rats and control animals, calcium only arrives via potential-dependent Ca-channels when synaptolemma is depolarized. Basic calcium uptake by brain synaptosomes of hypertensive rats is increased as compared to that of the control animals. Partial depolarization of the synaptosomal plasma membrane in hypertension may be caused by its increased permeability by sodium. When Ca2+ concentrations are low, its mitochondrial accumulation rate is increased, and microsomal rate, on the contrary, decreased in the brain of hypertensive rats. The effect of calmodulin on the microsomal calcium accumulation rate is essentially lower in hypertensive rats as compared to the controls. The described disorders of synaptosomal Ca-transporting systems in rats with spontaneous hypertension can obviously result in changed neuromediator secretion rates in nerve endings.