[Intracellular concentration of free calcium in thrombocytes: its characteristics in spontaneous hypertension]

Using the fluorescent Ca-dependent dye quin-2 the authors measured the concentrations of free calcium in the platelet cytoplasm of rats with spontaneous hypertension (SHR) and in normotensive rats (NKWR) serving as control. There were no differences in the baseline levels of free Ca2+ between the platelets of the SHR and NKWR rats. When the cells were loaded with quin-2 in a calcium-free medium and transferred into a medium containing 1 mM of CaCl2, the concentration of Ca2+ in the platelets of the SHR rats became higher. An increase in the content of intracellular Ca2+ induced by thrombin administration was 70% higher in the platelets of the SHR rats as compared with the NKWR rats. The findings obtained suggest that the insufficiency of the Ca-transporting systems of the cellular membranes in primary hypertension described earlier is attended with disturbances in the regulation of the levels of cytoplasm free calcium.